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AGRICULTURE OF THE SUGAR-CANE

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Frontispiece.-—A focal point. M o n y m u s k Sugar Factory, Jamaica, B . W . I .

[Courtesy of West Indies Sugar Co. Ltd.

AGRICULTURE OF THE

SUGAR-CANE

by

A. C. BARNES C.M.G., B.Sc. (Hons.) Vict., F.R.I.C,

A.M.I.Chem.E.

Formerly Director of Agriculture, Fiji; and Jamaica; General Manager, West Indies-Sugar Co. Ltd., and

Director of Research, Sugar Manufacturers' Association (of Jamaica) Ltd.

LONDON LEONARD HILL LIMITED

9 EDEN STREET, N.W.1. 1953

First published 1953

PRINTBO IN GREAT BRITAIN

BY W. & J. MACKAY & CO., LTD., CHATHAM

LIST OF ILLUSTRATIONS

Frontispiece

PAGE

3 facing 6

"

" "

"

7 22

23 23 48

48

49 facing 70

" "

71

71

78

Focal point. Monymusk Sugar Factory, Jamaica, B.W.I.

FIG.

1. Map of sugar areas 2. Cane fields and drainage ditches, Florida 3. A sugar estate in Puerto Rico 4. Cutting cane, Dominican Republic 5. Water transport of sugar-cane 6. Natal. Rolling fields of sugar cane near the sea 7. Features of the cane stalk

8. The early growth stages 9. Development of secondary shoots

10. Arrowing (flowering) 11. Drainage ditch, Florida Everglades 12. A moling plough, Florida Everglades 13. Field layout, British Guiana

14. Seedling nursery, B.W.I. Sugar Cane Breeding Station, Barbados facing 86

15. Vertical photograph of sugar estate in Jamaica, showing natural and artificial drainage facing 87

16. Vertical photograph of sugar estate in Jamaica, showing reaped fields facing 134

17. Map prepared from aerial survey „ 135 18. Cambered beds 138

19. Applying Sulphate of Ammonia by hand to plant cane, Jamaica

20. Mule-drawn light implement on Natal Estates 21. Inter-row cultivation 22. Anhydrous ammonia storage 23. A cane-cutting gang, Clewiston, Florida 24. Westbrook Dam, Natal Estates Ltd. 25. Pomona Deep Well Turbine Pump 26. Deep well pump installation, Cuba 27. Pump characteristic diagram

facing "

" " "

"

facing

150 151

151 2 3 0

2 3 0

2 3 1

2 4 2

246

249

vi ILLUSTRATIONS

FIG.

28. 29.

30.

31.

32. 33. 34.

35. 36.

37. 38.

39. 40.

4 1 .

42.

43. 44.

45. 46.

47. 48. 49.

50. 51. 52.

53. 54. 55.

56.

57.

58.

59. 60.

Cross section of water well The original track-type tractor, 1904 An early track-type tractor Heavy disc plough, maximum ploughing depth 14 in. of furrow 14 in. Ploughing in Natal Heavy disc plough-harrow, Zululand Discing and smoothing in muck soil, Florida Two standard heavy subsoil attachment

Subsoiling in Reunion Cultivation of ratoons in heavy trash Equipment for cultivating ratoons

Notched " chopper " discs Chopper gangs and tool-bar mounting

" Barring off " and cutting furrow for irrigation Transfer hoist, Jamaica Thomson Hurrycane Harvester Mechanical planting in Natal 4-ton steel cane cart Train of steel-bodied cane carts Loading tractor carts A loaded train of cane carts Cane transport, Cuba

Cane hauling in Panama 10-ton transfer hoist and weigher, Florida Moving portable tracks, Peru Motor grader, Hawaii

A plantation shop, Clewiston, Florida

The research station at Mount Edgecombe, Natal, Africa Sugar plantation in Jamaica

PAGE

251 facing 278

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, width 278

facing 279

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"

"

"

"

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"

"

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"

"

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" South

279 294 294

295 295 298 298

299 299 306 306

307 307 310

310

311 311 326 326

327

327 342 342

facing 343

"

Two-row cutter-planter with fertilizer attachment, Queensland Cultivating young cane, Hambledon, Queensland Helicopter in operation

facing

"

"

Unloading sugar-cane at a factory near Cali, Colombia

358

359 359 374

375

CONTENTS

CHAPTER PAGE

PREFACE ix

1. THE SUGAR-CANE, A MAJOR WORLD CROP I

2. THE PRINCIPAL CANE-SUGAR PRODUCING COUNTRIES 6

3. THE PLANT AND ITS PROPAGATION 44

4. SUGAR-CANE SOILS 52

5. THE DRAINING OF SUGAR-CANE LANDS 66

6. PESTS AND DISEASES, THEIR EFFECTS AND CONTROL 82

7. SUGAR-CANE VARIETIES AND PLANT BREEDING 95

8. PLANTATION AND FIELD PLANNING 113

9. THE PLANTING AND CULTURE OF THE CANE 135

10. FERTILIZERS AND MANURES, THEIR APPLICATION AND

EFFECT 154

11. WEEDS AND THEIR CONTROL 178

12. HARVESTING THE CANE 193

13. IRRIGATION 208

14. MECHANIZATION OF SUGAR-CANE AGRICULTURE 253

15. MANAGEMENT, SUPERVISION AND STAFF 296

16. FARM AND FIELD RECORDS 310

17. CANE FIRES AND THEIR CONTROL 327

18. METHODS OF COMPUTING THE PRICES OF FARMERS'

CANES 332

19. THE SUGAR-CANE AS AN INDUSTRIAL RAW MATERIAL 339

20. RESEARCH AND THE PLANTER 351

21. PLANTERS' ORGANIZATIONS 362

22. THE OUTLOOK 376

TABLES AND MISCELLANEOUS INFORMATION 382

ACKNOWLEDGMENTS 386

INDEX 387

vii

PREFACE

The cane sugar industry of the world has expanded remarkably since the beginning of the century. Accompanying the enormous increase in production are great changes in field and factory practice, which in many countries have brought about the replacement of the small self-contained sugar estate by large plantations and central factories. Coincident with these developments have been progress in organization, control and management; intensive research on the great range of varied problems of the industry ; recognition of the need for special training of staff of all categories ; the organization of the various grouped interests which comprise the whole industry ; and the application of modern science to every phase of the work of producing cane sugar.

The object of this book is to discuss in broad outline the varied facets of the agriculture of the sugar-cane as they present themselves to the staff of a well-organized and efficiently conducted sugar-cane plantation. The term " agriculture" has for this purpose been used in a much wider sense than its usual dictionary definition, so that in addition to the general picture of agricultural practices, attention is devoted to matters which directly impinge upon and affect the success of the extensive range of field operations which are necessary to grow, reap and market sugar-cane successfully and profitably. The treatment of the subject has been largely conditioned by wide experience in agricultural administration, sugar plantation management, and research in many parts of the British Commonwealth.

Grateful acknowledgment is recorded for advice and assistance in regard to the compilation, the material used in it and the figures used to illustrate it, from numerous sources of which particulars are given in an appendix. It is not possible within the scope of one volume to deal comprehensively with every part of this vast subject, and those who may expect a complete presentation will be disappointed. Details of practice vary so widely and conditions differ so much that at least one volume would be needed to deal with each country in which the production of cane sugar is an

ix

X PREFACE

important industry, as well as for each branch of the varied subjects involved. The fact that there appears to be no recent book on the general subject of the agriculture of the sugar-cane, and the need for one that will be helpful to large numbers engaged in the various activities of the industry has stimulated this compilation.

CHAPTER 1

T H E S U G A R - C A N E , A M A J O R W O R L D C R O P

T h e S u g a r - C a n e a n d i ts P r o d u c t s

Sugar-cane, a giant member of the grass family, is the most important source of cane sugar or sucrose, itself one of a large family of sugars. Sugar-cane is responsible for the world production of more than 20 million tons of sucrose annually and is widely grown as a plantation crop throughout the tropical and sub-tropical regions. Known botanically as Saccharum officinarum, again one of many species of the genus, it provides the cheapest form of energy-giving food with the lowest unit of land area per unit of energy produced. Although sucrose alone is not a diet on which man can live it represents about one-seventh of the total energy intake of human food for a normal person under non-restricted conditions of supply. It has been stated that an average man's annual food consumption is equivalent approximately to 1 million calories. Under present agricultural systems this is produced by one-eighth of an acre of sugar-cane, while whole wheat flour requires 7 times, milk 20 times and beef over 100 times as much land to produce the same amount. These striking facts serve to emphasize the importance of sugar-cane as a source of food, but consideration of the numerous other direct and indirect products derived from the cane gives an even more impressive conception, since apart from its varied uses as a food and sweetening agent, sucrose is extensively used in the arts and manufactures, while it is coming into increasing prominence as a raw material for the production of a variety of important chemicals including such diverse products as refrigerants and drugs.

The residues of cane sugar extraction yield still more raw materials used in manufacture. The exhausted fibre (bagasse or megass) consists largely of cellulose and is used for making compressed fibre board, paper and cattle food. The dark, sugary syrup remaining after the factory process has separated the recoverable sucrose, known as molasses, is a source of alcohol both as potable spirit (rum and gin) and for industrial use, as well as

2 AGRICULTURE OF THE SUGAR-CANE

bakers' yeast and dry ice. During recent years it has come into prominence for the manufacture of food yeast, rich in protein a n d vitamins. A valuable wax, found on the outer surface of the cane can be extracted from the mud separated from the juice in t h e sugar factory process.

A Continuing Crop The sugar-cane itself, though reaped annually, is not strictly

speaking an annual crop, as successive growths are obtained from the same planting. Consequently agricultural operations are n o t confined to the immediate requirements of one crop, but mus t take into account those to be harvested in later years from t h e same land. A factor of major significance is that sugar-cane u n d e r a proper system of land management maintains and improves the fertility of the soil. This is of the highest importance in island territories where arable land is limited and populations are increasing. It is of even wider importance when considered as a major contribution to safeguarding and using to the best advantage the diminishing reserves of land required for the maintenance of food supplies for the population of the world.

Historical The sugar-cane has been known from the earliest times and is

referred to in historical records going back into the remote days of ancient civilizations which flourished long before the Christian era—though the actual extraction of sugar from it does not appear to have been discovered until much later.

It is now agreed that the original home of the sugar-cane is t h e islands of the Pacific region from whence it spread to other pa r t s of the world. It spread first to the Asiatic mainland, notably to India, to the southern parts of China and adjoining countries, where the manufacture of sugar or a sugary product from it first originated. From there it spread via Persia and the countries of t h e Middle East to the Mediterranean region, including North Africa and Egypt, as well as some southern European countries, notably Italy and Spain ; in Egypt and southern Spain sugar-cane cult ivation is still an important industry, but in the others it has died ou t .

Columbus seems to have been responsible for the first i n t r o duction of sugar-cane to the islands of the West Indies in 1493.

FIG. I.—Map of the world with cane-sugar growing areas shown in black.


though it was not until a few years later that the crop was successfully established in Hispaniola where sugar was made in 1509. From there the crop became distributed throughout the other islands of the West Indies, to the southern States of North America and to many countries in the South and Central American region.

In Jamaica at the time of the English conquest in 1655, there were three small sugar plantations. The first English plantation there, owned by Sir Thomas Modyford, made sugar in 1664. The sugar industry seems to have developed steadily in the eighteenth century and in 1789 there were 710 sugar plantations in the Island and two years later the number had increased to 769. The record output of this earlier period was in 1805, when the yield was 120,280 tons. Other territories of the British West Indies have similar records. Sugar-cane has been the principal crop of Barbados for more than 250 years, and of Antigua since 1671. In British Guiana the first horse-operated mill was erected in 1664, and production in the 1820's approximated 60,000 tons of sugar annually.

The story follows somewhat similar lines in islands as far distant as Hawaii and Mauritius, in both of which the crop was being grown in the eighteenth century. More recent cane-sugar producing countries are Australia, Fiji and South Africa. Cuba, in the latter years of the eighteenth century, contributed some 15,000 tons of cane sugar to world trade and reached 1 million tons 100 years later, the present-day output being about 6 million tons.

In Java, under Dutch influence, sugar-cane cultivation expanded enormously during the nineteenth and early twentieth centuries, and in the years before the last war reached approximately 3 million tons, while under Japanese influence sugar production in Formosa attained the million-ton mark.

The list is not exhaustive nor is the narrative complete, but it gives an indication of the history of a crop which has swayed the destinies of whole peoples and has played on many occasions a dominant part in inter-territorial policies and even in wars.

Sugar and Politics The industry has experienced many and violent disturbances

with fluctuations in output and profit resulting from political

THE SUGAR-CANE, A MAJOR WORLD CROP 5

changes, trade problems and war. In many parts of the world, particularly in the Caribbean area and Louisiana, the slave system on which the planters relied for their labour offended the outlook of right-thinking people and its abolition at various times in the different countries caused a temporary setback in production. The American Civil War brought about developments in Cuba and Hawaii, and the Spanish-American War while adversely though temporarily affecting Cuba, caused expansion in Puerto Rico and the Philippines. The sugar bounties of the late nineteenth century, abolished in 1903, profoundly depressed the British West Indies and special forms of assistance had to be devised to revive the industry.

CHAPTER 2

THE PRINCIPAL CANE-SUGAR PRODUCING COUNTRIES

CANE SUGAR CROPS*

United States : Louisiana Florida Puerto Rico . . Hawaiian Islands Virgin Is lands . .

Cuba

British West Indies : Trinidad Barbados Jamaica Antigua St. Kitts Other B.W.L . .

French West Indies : Martinique Guadeloupe . .

Dominican Republic

Haiti

Mexico

Central America: Guatemala Salvador Other Central Americ

South America: Demerara (British Gu Colombia

•Wil le

1951-52 Long Tons Short Tons Metric Tons

264,791 108,035

1,214,144 965,000

8,000

7,110,438

137,358 156,742 265,872

34,000 47,100 15,000

65,000 85,000

583,242

57,600

764,000

60,000 26,000

a 65,000

iana) 236,058 185,000

tt & Grey, 11 Sept.,

6

296,566 121,000

1.359,841 1,080,800

8,960

7,963,691

153,841 175,550 297,777

38,080

52,752 16,800

72,800 95,200

653,231 64,512

855,680

67,200 29,120 72,800

264,385 2 0 7 , 2 0 0

1952.

269,040 109,769

1,233,631 980,488

8,128

7,224,560

139,563 159,258 270,140

34,546 47,856 15,241

66,043 86,364

592,603

58,254 776,262

60,963 26,417 66,045

239,847 187,969

F I G . 3.—A sugar estate in Puerto Rico. [Courtesy of Caterpillar Tractor Co.

THE PRINCIPAL CANE-SUGAR PRODUCING COUNTRIES 7

Surinam Venezuela Ecuador Peru Argentine Brazil

Total America

India and Pakistan (Gur.)

India and Pakistan (White)

Java

Japanese Empire

Taiwan (Formosa)

Philippine Islands

Total Asia

Australia

Fiji Islands

I95I-52 Long Tons Short Tons Metric Tons

8,000 54,000 45,000

475,000 650,671

1,866,454

15,552,505 3,795,000

1,350,000

467,986

40,000

550,000

937,5oo

7,140,486

744,861

113,000

Total Australia and Polynesia 857,861

Egypt Mauritius

Reunion

Natal and Zululand

Mozambique

Angola

British East Africa

Total Africa

Europe-Spain

Total Cane-Sugar Crops

190,000

483,904

120,000

475.451 80,000

50,000

80,000

1.479.355 22,000

25,052,207

8,960 60,480 50,400

532,000 728,752

2,090,428

17,418,806

4,250,400

1,512,000

524,144

44,800

616,000

1,050,000

7.997.344 834,244

126,560

960,804

212,800

541.973 134,400

532.505 89,600

56,000

89,600

1,656,878

24,640

28,058,472

8,128

54.867 45.722

482,624 661,114

1,896,411

15,802,123

3.855.910

1,371,668

475.497 40,642

558,828

952,546

7.255.091 756,816

114,814

871,630

193.050 491,671

121,296

483,080

81,284

50,803

81,284

1,503,098

22,353

25.454,295

United States of America The sugar-cane industry of the United States mainland is

centred in Louisiana and Florida. The total production of cane in 1949 for the manufacture of sugar exceeded 6 million tons, which yielded 521,000 tons of 96o sugar.

B


Louisiana The total area reaped in 1949 amounted to 279,000 acres with

average yields of 17.9 tons per acre of cane and 1.5 tons of sugar. There are at present 54 operating factories, the total sugar production in 1950-51 amounting to 456,246 tons. A high proportion of the cane supplied to the mills is grown by independent farmers, and in several cases the milling companies are owned by co-operative groups of growers.

Agricultural practice in the cane lands is conditioned by the high water table and cold winter period extending from December to March. Detailed discussions of cultivation and planting methods, and drainage are given in Chapters 5 and 9. The Industry has been quick to adopt new and approved methods in all phases of the work of cane-sugar production. Field operations, including harvesting and loading are highly mechanized. Powered drag lines are largely used for the construction and maintenance of drainage works.

The cane is planted in the fall of the year, commencing usually in September and a cover crop of Melilotus indica is planted between the rows, being ploughed in during the course of the first cultivation operations at the beginning of March. C.P. varieties are principally grown, though comparatively small areas are planted in C0.290 and miscellaneous canes. Green manuring is practised, the crops used being soy beans, peas, and winter vetch. Considerable areas of corn are grown with soy beans in cane lands between successive planting cycles. The fertilizers used include ammonium nitrate, cyanamide aeropril and anhydrous ammonia which is rapidly replacing other nitrogeneous fertilizers. Several plantation groups have erected storage installation tanks, usually of 30,000 gallon capacity.

Weed control is carried out by flaming, the use of new herbicidal mixtures, and intensive ploughing, particularly for Johnson grass, Sorghum halapense, which is difficult and costly to control. In recent years sheep have come into increasing use to assist in the control of Johnson grass. A measure of the trouble occasioned by this weed is indicated by the practice of many farms of fallow ploughing at 3-weekly intervals from early March until September when fall planting begins. Pre-emergence weed control is carried out by applying 1 to 2 lb. 2-4D equivalent per acre over the whole


planted area, followed by spraying of the rows only in the early and late spring, when weeds between the rows are controlled by the cane cultivation tools. Among the pests, the cane borer gives trouble in some districts. Successful control has been achieved in one area by four dustings with Cryolite, and three additional applications of Ryania, the whole of which work was done by aeroplane.

Several plantations maintain high volume low lift pumping installations for drainage maintenance. The pumps in general use are Pomona and Fairbanks-Morse-Pomona, power being derived from natural gas engines, Allis Chalmers tractor engines and, in one case, by steam produced in a gas-fired boiler.

The harvesting season extends from mid-October to late December and occasionally early January. Factories are of relatively high daily grinding capacity in order to compensate for the comparatively short growing season and the necessity for quick harvesting in order to avoid damage and loss by frost, which can be very serious. The cane deliveries to the factories are usually by tractor-drawn trailers, motor truck and trailer combinations, plantation and standard gauge railways. At the Cypremont Factory, one quarter of the supply is water-borne.


Fallow land is planted with the cover crop, Sesbania spectabilis, which is sown from the air. It is stated that this method has proved highly efficient and economical. The cane is planted in furrows by hand during the period August to the end of October, three rows at once being covered by tractor drawn closing discs.

Fertilizing is done during October and November after the normal hurricane season, during which heavy rainfall is often experienced which might cause loss by leaching. Standard fertilizers with magnesium oxide, and occasionally secondary elements, are used. Plants are reaped at about 15 months and ratoons at 12 months. Attempts to use mechanical harvesting have not been successful because of the effect of flood and storm damage on the cane which develops a recumbent and tangled habit.

The serious pests of the cane are rodents and the moth borer. Rat control is carried out by the distribution of poisoned bait by aeroplane three times during the growing season. Poisoned wheat in waxed paper pellets, and diced sweet potatoes are used, the most successful poisons being zinc phosphide and thallium sulphate. The borer parasite, Lixophaga saccharalis is bred in large numbers and released in the fields. The parasitic wasp, Bassus stigmaterus, Cress, introduced in 1936 has become established and is assisting in borer control.

The U.S.A. Sugar Corporation controls a total area of 137,000 acres comprising a sub-drainage district, of which 33,000 acres are cropped annually, producing some 950,000 tons of cane each year. The factory has a daily grinding capacity of 6,500 tons. The principal varieties grown at present are F.31/92 and F.31/436. All field operations are fully mechanized with the exception of the reaping of cane. The total tractor horse power for cultivation operations and haulage is approximately equivalent to 7.25 acres per h.p. Great savings have been effected by the use of chemical weedicides. Low fibre canes have been developed in the course of the breeding programme. Complete details of the composition of typical soils have been obtained by spectrographic analysis.

Puerto Rico Puerto Rico is the most easterly of the islands of the Greater

Antilles, in the West Indies, and is 3,435 sq. miles in area (Fig. 3). A territory of the United States of America, it is self-supporting,


and mainly dependent on the cane sugar industry. The annual production of sugar now exceeds 1 million tons annually, and amounted to 1,140,000 tons in 1951. The area harvested each year is about 400,000 acres. Yields of cane and sugar per acre are closely comparable with those of Jamaica. The island is within the West Indian hurricane region. Rainfall varies from year to year, the island average ranging from 43 in. (1930) to 87 in. (1931), with considerable differences from one part of the island to another. Irrigation is extensively practised in the drier areas where annual rainfall is below 20 to about 60 in. The overhead method has proved highly satisfactory in limited areas. Water is supplied by the Government irrigation service from gravity supplies, and there are private gravity and pumping systems using water from streams and wells.

The sugar-cane soils are conveniently divided into two main types, those of the humid areas where rainfall is 60 to 100 in. yearly, and those of the arid districts with rainfall below 60 in. The former are highly acid, but richer in organic matter, being lower in P2O5 and lime. The potash and nitrogen status are similar for both. In general the soils are less difficult to work than those of Jamaica. Land preparation and tillage are highly mechanized except in hilly districts. The gyrotiller is largely used. Deep sub-soiling down to 27 in. is carried out in soils of Turner's Group II. The sequence of operations in the south central area for land to be replanted is deep knifing, disc ploughing, harrowing and furrowing, using diesel powered tractors of various makes and sizes including D4 to D7, TD9 to TD18, and HD5 to HD10. Lighter free draining soils are disc ploughed twice and harrowed before the furrows are put in. Heavier lands with more difficult drainage conditions are planted on the bank system with two cane rows on the bank, and drains between the banks. In some areas fields have been tile drained, one company having 700 acres of such land.

Cattle are still used for minor field operations and haulage purposes to a considerable extent. Planting is done almost entirely by hand. Weed control by the use of herbicides is increasing. Manual reaping and loading with Link-Belt speeder cranes has recently been introduced. Transport of cane to factory or railway from the field is carried out in various ways using cattle carts,


motor trucks, tractor hauled rubber-tyred carts, and portable track. It is estimated that over 90% of the cane is mechanically transported.

Cane Varieties The variety position during recent years has been mainly

affected by the incidence of mosaic disease which caused severe damage to the noble canes grown up to 1920. Early P.O.J, varieties and Uba were successfully introduced, the latter being extensively grown until 1925. The high yielding qualities of B.H.10/12 and S.C.12/4 brought about the replacement of Uba, though their susceptibility to mosaic was a drawback. P.O.J.2725 and P.O.J.2878 came later and became widely cultivated, being followed by new varieties produced by the Puerto Rico Experiment Station at Mayaguez and at two other breeding centres in the Island. More recently P.R. varieties and new ones from Barbados, particularly B.34104 and B.37161 have been commercially planted. The mosaic disease position in Puerto Rico appears to be under better control than in Jamaica. B.H.10/12 and P.O.J.2878 are still extensively grown.

Fertilizers Heavy fertilizer dressings are applied and a range of different

NPK mixtures used which must conform to the formulae prescribed each year by the Department of Agriculture. This is criticized locally at a high level because of the waste and cost of mixtures which in many cases are unsuitable. The methods and rates of application vary considerably. In irrigated land plants receive 400 lb. per acre of 14-6-5 mixture six weeks after planting, and 600 lb. sulphate of ammonia six weeks later, applied in the irrigation water. Ratoons receive the same dressings. A high rainfall area is given 1,200 lb. 14-4-10 mixture in two equal doses, with 6 to 8 weeks between applications, both for plants and ratoons. Another example in a high rainfall district is the use of 1,800 lb. per acre of 10-6-16 mixture in three applications to plants at 1 week, 7 weeks and 3 months after planting. Ratoons are given 800 lb. just after reaping and a similar quantity about 6 weeks later. Lime, and filter mud are used. Research has shown no advantage in more than one application of fertilizer.


Government Control The organization of the industry has been profoundly influenced

by the enactment of Law 26 of 1941 which amongst other things provided for the establishment of a Land Authority, and made it illegal for "artificial persons," i.e., companies and corporations to own more than 500 acres of land. As a result of this the factory-owning companies are now in the position of processors of cane grown by other persons. The Land Authority has progressively acquired the plantations formerly owned by the factory companies, and in a few years the whole industry will have been subdivided into the two groups, planters and manufacturers. There is no restriction on the area held by an individual. Sugar manufacturing companies have formed separate organizations for their agricultural activities, one of which operates on a large scale as the "colono" or farmer supplying to three factories. In the following year a further law brought the sugar industry under the authority of the Public Service Commission by declaring the manufacture of sugar to be a public service enterprise. The latter law was found difficult to administer and was repealed in 1951, when a sugar board was created as an addition to the Department of Agriculture for the purpose of regulating the business relations between farmers and factories and exercising other controls over the industry.

Research Research work including cane breeding is conducted by the

Agricultural Experiment Station of the University of Puerto Rico.

Territory of Hawaii The cane sugar industry of Hawaii displays a number of un

usual features. The average growth period is from 18 to 24 months per crop, and approximately half of the total area in cane is reaped annually; thus in 1950 the total area in cane exceeded 220,000 acres, of which 109,400 were reaped for sugar manufacture. This area yielded 8,174,800 tons of cane, equivalent to an average yield of 74.7 tons cane per acre or 8.78 tons of sugar per acre. Approximately half of the cane land is irrigated, and yields two-thirds of the yearly cane crop. Plantations and factories are distributed on


the four principal islands of the group. During the past 25 years the annual production of 96º sugar has exceeded 1 million tons on four occasions. The output for the 1950 crop was 960,961 tons.

Mechanization The production of cane is highly mechanized. The Industry

had to effect a change because of serious labour difficulties culminating in the great sugar strike, which broke out on the 1st September, 1946, and continued until the 19th November. Former methods which involved the use of manual labour as well as animals and a considerable degree of mechanization were already undergoing progressive changes, and had as a result to be more quickly altered, principally for harvesting operations. The profound effect of this revolution is experienced in all phases of the Industry, including the factories, where cane cleaning plants, costly both in erection and maintenance, have had to be installed to remove the large quantities of earth, stones, partly burnt trash and other rubbish before the cane can be milled.

Harvesting While general cultivation operations follow a very similar

pattern to those used in other countries, mechanical harvesting has had largely to be improvised in order to meet the immediate needs brought about by the forced change from hand to mechanical cutting. Most estates now conduct reaping by pushing the cane over either by means of forward mounted bull dozer type cutting rakes and high powered tractors or by drag line rakes drawn by tractors with side-mounted winches. The cane is wind-rowed or pushed into heaps in the fields, and grab loaded into trucks ranging in capacity from a few tons up to 50 tons. In a few cases the cane is water flumed to factories. In many instances plantation railways have been abandoned in favour of road haulage which is found to be more efficient and flexible and cheaper in operating cost. Extensive improvements to estate road systems have become necessary because of the heavy loads carried.

Cultivation The heavy reaping and transport equipment has been found to

cause serious soil compaction on many estates, which has reduced the number of ratoon crops, and made it necessary to use very


heavy rippers and sub-soilers for deep cultivation. The sub¬ soiling of ratoons has been found to break up compacted soil resulting from mechanical harvesting.

A great variety of tractors and equipment is used, including a number of high clearance track-type machines, some of which have been converted in estate workshops. Deep ploughing by the Towner Plough with four or five 44 in. discs turns over the soil to a depth of 22 in., and in some cases sub-soiling to a depth of 24 in. is practised. Planting is partly mechanized, and in one case seed pieces from whole canes are cut to length, dropped and covered by one machine.

Weed control is almost entirely carried out by a combination of pre-emergent and herbicidal spraying, and the use of light cultivation equipment. Spraying for hillside weed control has been found successful and in at least one case helicopter application has been used. Applications of nitrogen, phosphoric acid and potash are made in varying amounts, in accordance with requirements which in some cases are determined by rapid methods of soil testing, and by foliar analysis of cane leaves. The application of nitrogen in the form of urea by aeroplane to the growing cane gives promise of crop improvement by absorption of the material through the leaves.

Fertilization, irrigation and ripening are largely guided by the Clement's Crop Log Method (page 224).

The Island of Hawaii, 4,030 sq. miles in extent, has about 97,000 acres devoted to sugar-cane. There are thirteen factories and plantations, of which two are in the south-east and the others in the east and north-east, there being none on the western side which is extremely mountainous.

The cane areas extend from sea level to an altitude of 2,000 ft. or more. On this island cane is almost entirely produced under natural rainfall conditions in areas ranging from just above sea level to more than 2,000 ft. altitude. The rainfall is generally heavy and increases with altitude, though the Kohala Sugar Company at the extreme north tip reports an average rainfall of only 29 in. An extensive irrigation system is established on this estate consisting of a gravity supply from surface and spring water collected in the mountains and delivered either to reservoirs or direct to fields, and three primary pumping stations lifting water


from tunnels at sea level, with secondary stations to boost the water to higher points. In other areas of the island the variation of rainfall with altitude is illustrated by the records of Olaa. The average annual rainfall at no ft. is 106 in. ; at 670 ft., 140 in.; and at 1,530 ft., 191 in. In general the yields of sugar per acre on Hawaii are lower than those in the other islands.

The Island of Kauai, the most westerly of the cane sugar producing islands of the Hawaiian Group, though only 555 sq. miles in extent, has some 45,150 acres devoted to sugar-cane, the production of sugar in 1950 being 211,690 tons. The eight sugar estates practise complete or partial irrigation, the average rainfall being much lower than in the cane areas of the island of Hawaii. On some estates irrigation is confined to the lower lands, as the rainfall in higher areas is adequate. An example is Grove Farm where the lower fields are entirely irrigated, the mid-section fields partly irrigated, and the upper fields not irrigated. Much of the water is obtained by gravity from the mountains where rainfall is very high, but there are powerful pumping units lifting water in one case against a head of 433 ft. and delivering 30 million gal. a day.

The Island of Maui is 728 sq. miles in extent, the approximate area in cane being 38,700 acres. Sugar production in 1950 was 212,690 tons. There are now three operating sugar companies of which the Hawaii Commercial and Sugar Company is a merger which includes the former Maui Agricultural Company Limited. The total cultivated area of all the estates is irrigated. Rainfall is very low, ranging from 10 to 34 in. per annum. Water supplies are derived from mountain sources and from extensive pumping systems, water being lifted in large volumes to heights of several hundred feet and in one case to more than 500 ft. Yields of cane and sugar per acre are high, and in one case the recovery amounted to an average of 12.81 tons sugar per acre for an area of over 11,000 acres. With the exception of one company which continues to use railway transportation, the cane is moved to the factory by heavy haulage vehicles of various types.

The Island of Oahu is 604 sq. miles in area with about 36,000 acres in sugar-cane. Sugar produced in 1950 amounted to 219,730 tons. There are four plantations and factories, of which three are among the larger in the whole group. The entire area of


all plantations devoted to sugar-cane production is under irrigation. With annual average rainfall of about 20 in. the Ewa Plantation Company depends entirely on artesian water. This is derived from 63 drilled wells, 5 surface wells and a shaft and tunnel system from which water is lifted by 22 pumps to heights varying from 20 to 200 ft. with an average of 99 ft. There is an extensive system of steel irrigation pipe lines and of concrete pipe. Pump water on Kahuku is lifted as much as 225 ft. with an average of 68 ft. Booster pumps supplement the main system, the highest total lift being 292 ft. The Oahu Sugar Company Ltd., which harvested 7,145 acres of cane in 1950 with an average yield of 10.92 t.s.a., has an average annual rainfall of 26.6 in. and an average water requirement for irrigation purposes of 125 acre in. per crop, equivalent to 140 million gal. of water per day supplied to the fields. The extent of the system is indicated by the length of the 41 tunnels which amounts to 15 miles with 27 miles of open line ditches and a number of reservoirs supplied by a mountain water system, while there are 39 pump units which provide about 70% of the total water used. The largest pumping unit lifts 11 million gal. a day of water from sea level to 630 ft. elevation. Two plantations continue to use railway transport.

Cuba Cuba, situated within the northern tropics, is the largest of the

Greater Antilles, 44,164 sq. miles in extent. A distinct wet season occurs from May to October, with a dry season, October to May. The average annual rainfall varies from 40 to 75 in. in different zones of the island.

There are six provinces in each of which the cane sugar industry is carried on. The total area of cultivated land in 1950 was 1,616,000 hectares, of which 923,100 hectares representing 57%, were devoted to sugar-cane. The more important sugar producing provinces are Camaguey and Oriente. The total cane produced for the whole island was 41,834,000 long tons in 1950 from 2,945,455 acres. There are 161 sugar factories, which operate railways of a total length exceeding 11,000 km., of which about two-thirds are standard gauge. The greater proportion of the sugar-cane is produced by growers, of whom there were 39,634 in 1950; 21.3% is grown by the factory organizations.


The production of sugar in 1901 amounted to 635,800 tons, which steadily increased to a little more than 3 million tons in 1916, 4 million tons in 1922 and 5,189,000 in 1925, remaining fairly steady for the next five years. There was a decline, caused mainly by economic and political changes, to barely 2 million tons in 1933, followed by a recovery which brought the output to 3,345,000 tons in 1942. Considerable fluctuations took place during the second world war period, after which 5 million tons was again exceeded in 1947, and 5,876,000 tons reached in 1948, when the estimated value of the sugar was 550 million dollars. The total value of the industry, including molasses, closely approached 592 million dollars.

The variety position in Cuba is particularly interesting. "Cr is¬ talina" accounted for 13.2% of the total weight reaped for the 1949 crop. Unlike the old standard noble canes of other countries, this has retained an important position in Cuba for very many years, and has only been surpassed by P.O.J.2878 in recent times. That variety provided 61.7% of the total cane in 1949. Others were Co.213 (3.9%), Co.281 (2.74%) and six other P.O.Js. totalling 6.46%.

J a m a i c a Jamaica is situated between 17º 43' and 18º 32' north latitude

and 76º11' and 78º 21' west longitude. The total area is 4,411 sq. miles, of which the greater part consists of hilly and mountainous lands, the highest altitude being 7,402 ft. at the Blue Mountain Peak in the east. There are wide ranges of climate and rainfall, from the hot humid coastal plains to the cool uplands, with less than an average of 30 in. of rain yearly in the south central coastal areas to more than 100 in. in the north-east. The mean maximum and minimum temperatures of Kingston, the capital in the southeast of the island, are 87.60 and 71.2º respectively, the average rainfall for 70 years being 31.86 in. per annum. The island occasionally experiences hurricanes which cause damage to standing crops, though as a rule sugar-cane is not seriously affected.

Agricultural Conditions Approximately one-seventh of the total area consists of cultiv

able land of which 383,000 acres were in cultivation in 1942, 95,710 acres being planted with sugar canes. Soils range from


light alluvia with good drainage to heavy clays with impeded drainage. Sugar estates and factories are mainly situated near the coast, though some are inland.

Sugar Production Sugar production has long been important. Intimately asso

ciated with it is the manufacture of rum from the by-product molasses, and all sugar factories in Jamaica have distilleries attached to them.

During the past 30 years there has been marked centralization of the manufacture of sugar as well as a steady increase in annual production. In 1920, 59 factories made a total of 40,212 tons of sugar, while in 1949, 237,744 tons were produced by 23 factories.

Increased use of mechanical methods of cultivation has enabled greater crops to be grown without considerable increase in labour requirements, but for harvesting and transport they have grown more or less in proportion to the expansion of the crop. Mechanized agriculture, the careful use of fertilizers and better land management have contributed to the increased yields of cane and sugar. A further important feature has been the introduction of new and improved varieties of cane from the B.W.I. Central Sugar Cane Breeding Station in Barbados, from which final selections for commercial planting are made after experimental trial. This has brought about remarkable changes in the varieties of cane grown by estates.

Irrigation More than 40% of the crop is grown under irrigation in the

southern central area where rainfall is deficient. In the eastern portion the principal source of water is the Rio Cobre Irrigation Scheme, while in the west the so-called Cockpit Scheme is the largest similar source. Both were established by the Government and are operated under appropriate legislation. In addition there are numerous tube wells on estates from which water is pumped for the irrigation of localized areas while other estates outside the dry belt have local gravity irrigation systems.

Production In 1949 the sugar crop of 237,744 tons was derived from

2,212,220 tons of cane, of which 637,346 tons were grown by cane


farmers. During the past 16 years production by cane farmers has greatly increased ; thus in 1934 they supplied 13% of the cane used to make 72,420 tons of sugar, whereas in 1949 they were responsible for 28.81% of the cane used to produce more than three times that quantity. The relationships of cane farmers with factories are governed by the provisions of the Sugar Industry Control Law. Since 1938 cane farmers have been required to register with the factories they supply, and factories can purchase cane only from registered farmers. The total number of registered farmers at the end of August 1949 was 12,430.

The Leeward Islands This colony comprises St. Kitts, Nevis, Antigua, Montserrat

and the Virgin Islands. Sugar is mainly grown in St. Kitts and Antigua, which together produce from 40,000 to 60,000 tons of sugar annually. With the exception of Nevis, where production is still maintained on a small scale, sugar growing has largely died out in the other islands.

St. Kitts The island of St. Christopher (St. Kitts) is 750 miles distant

from Jamaica and is situated in latitude 17° 18' north and longitude 620 48' west. In shape it is rather like an Indian club. The north-western portion is an elongated oval, 14 miles long and 5 miles wide, having a central rugged mountainous range with its highest point, Mount Misery, 3,711 ft. above sea level. The total area is 68 sq. miles, with a population of 29,818 (census of 1946). The average annual rainfall for 34 years—1914-47—was 54.36 in., but considerable variations occur between the coastal plain and the uplands as well as from year to year. During the period mentioned the highest and lowest annual rainfalls were 77 in. (1932) and 34 in. (1923).

The whole economy of the island is dependent upon sugar, the cane being grown on the coastal plain encircling the north-western part, and on the inland slopes where the terrain is suitable for the crop. In common with other islands of the B.W.I. the sugar industry of St. Kitts suffered from severe depression during the closing years of the nineteenth century and the early 1900's. Apart from the external factors already discussed, inefficient small


muscovado factories, driven by windmills or steam, were operated by individual estates, and their low extraction of sugar contributed to the impoverishment of the industry. In 1912 a modern central factory—the St. Kitts (Basseterre) Sugar Factory Ltd.—was erected and commenced the manufacture of sugar. It handles the whole of the cane produced in the island and has now been in successful and highly efficient operation for 40 years. Prior to this the planters were losing 40% of the extractable sugar in their cane, and it has been estimated that in the first 14 years the new factory recovered 47,000 tons more than could have been got by the old mills from the same quantity of cane, the value of the sugar thus saved being in excess of £950,000.

The Factory Company grows no cane itself, but accepts deliveries from the 47 estates in St. Kitts which supply all but a small quantity of the total crop, the remainder being derived from small growers on land settlements and from the adjoining island of Nevis. The total area harvested annually is approximately 10,000 acres, the St. Kitts' crop being delivered to the factory by a 30-in. gauge railway which circles the main area of the island. Cane from Nevis amounting to 5,000 tons or so yearly is carried by sea.

Apart from the efficient extraction of the factory, improved yields of cane have been obtained by the estates as a result of organized investigations carried out since 1933 by the Sugar Cane Investigation Committee and various workers. From that time the damage and loss caused by the moth borer (Diatraea sac¬ charalis) has been progressively reduced by the agency of the Cuban Fly (Lixophaga diatraea). Mechanization of field operations and cane transport has advanced considerably during recent years. Contour cultivation is practised and the use of artificial manures has increased remarkably since 1933. Like other sugar-producing territories of the Caribbean, the industry in St. Kitts has derived great benefit from the work of the B.W.I. Central Sugar Cane Breeding Station in Barbados. Indeed it may be said that agricultural research has played a highly important part in improving the economy of cane production, while on the technical side the factory has contributed by a consistent and high standard of efficiency. 35,667 tons of sugar were produced in 1949, the five-year average for 1944-48 being 31,086 tons.


Antigua Antigua is another of the "sugar islands," 108 sq. miles in

extent. The history of the industry and its present condition closely follow the pattern of St. Kitts. The rainfall is lower with an annual average of about 43 in. ranging from 35 to 45 in. over the cane areas. Like St. Kitts the sugar industry is the predominant activity. At the time of the Norman Commission in 1897, sugar production was entirely an estate industry with 71 factories, of which 17 were windmill and 54 steam driven, all making muscovado sugar. As in St. Kitts, the manufacturing processes were wasteful, some 14 tons of cane being used to make 1 ton of sugar, compared with about 8 tons in the present modern central factory —The Antigua Sugar Factory Ltd.—which commenced operation in 1905 with a crop of 1,634 tons of sugar and now handles practically the whole output of the island. It has been enlarged and improved, and is now capable of an output in excess of 25,000 tons annually. The only remaining muscovado works is at Montpelier. The central factory purchases the whole of the cane ground by it, the supply coming from grouped and individual estates and from peasant growers.

Field investigations, commenced in 1891 and intensified in 1933, have made major contributions to improvements in cultural practices which have brought about higher yields. Crop fluctuations are related to the periodical droughts which characterize the climate, and in general the yields of cane and of sugar per acre are lower than in Jamaica or St. Kitts. In recent years difficulties with labour have intensified and interfered with the progress of harvesting and manufacturing operations both in Antigua and St. Kitts to a greater extent perhaps than in other parts of the B.W.L Thus in 1948 the combined effects of drought in 1946 and 1947 and of strikes during the cropping period caused a drop in the production of sugar to 12,174 tons in Antigua compared with almost twice as much in the previous year. The output in 1949 was 18,149 tons.

Barbados St. Lucia and St. Vincent both produce sugar in comparatively

small quantities. Barbados, the most easterly of the islands in the B.W.L, lies in latitude 13º 4' north and 59º 57' west, and is 166

F I G . 4.—Cutting cane, Dominican Republic,

[Courtesy of Caterpillar Tractor Co.

FIG. 5.—Water transport of sugar-cane, Richmond River, N.S.W.

[Courtesy Colonial Sugar Refining Co. Ltd., Sydney, Australia

FIG. 6.—Rolling fields of sugar-cane, near the sea in Natal.

[Courtesy of S. African Sugar Association


sq. miles in area. It has a remarkably high density of population, considerably in excess of 1,000 per sq. mile. The island provides a picture of well ordered agricultural activity, sugar-cane being the principal crop. Various vantage points enable the observer to overlook extensive areas of cane with sugar factories dotted through the landscape. Bridgetown, the capital, situated on the south-west, is a busy port where large liners and motor and sailing vessels of all descriptions make up picturesque seascapes.

The dominance of sugar is more apparent than in any other of the sugar islands. The industry, both in field and factory, is highly efficient and is a tribute to applied research conducted for many years by the Department of Science and Agriculture, and to the technical skill of the engineers, chemists and operatives of the factories. The B.W.I. Central Sugar Cane Breeding Station established in its present form in 1932, carried on the work of producing new cane varieties initiated many years earlier by J. R. Bovell and Sir John Harrison, and has evolved many new and improved canes now in extensive commercial cultivation not only in Barbados, but throughout the Caribbean area. Mosaic disease is no longer a problem, but moth borers (Diatraea sac¬ charalis) and, in localized areas, root borers, damage the cane and require special methods to combat their ill-effects. The former is partially controlled by the egg parasite, Trichogramma minutum, which is specially bred by the Department of Agriculture for liberation in the cane fields.

The average annual rainfall is about 64 in., but as in other islands considerable variations occur from year to year. There are three well-defined rainfall areas characterized as low, intermediate and high, with corresponding effect on growth and yields of canes.

In the low and intermediate rainfall areas the cane is mulched with grass which is cut and loaded mechanically and transported for application to the land. The importance of conserving soil moisture and fertility by this and other practices including the use of the dead leaves or trash from the cane at the time of reaping is well recognized. Additional yields of about 5 tons of cane per acre are obtained. Careful work over a long period has determined the optimum rates of application of artificial fertilizers and of grass for mulching the cane fields.

C


Until recent years there was very little mechanization of field operations, but of late the use of tractors and implements has developed. The extensive growing of food crops in sugar-cane land prior to replanting has great importance in relation to the production of as high a proportion as possible of locally-grown food.

Trinidad Trinidad lies to the east of Venezuela from which it is about

16 miles distant. Its area is 1,863 sq. miles, and with the small island of Tobago to the north-east it forms an administrative unit. It is the last, though not the least in importance, in this series of the sugar islands of the B.W.I. The sugar estates are situated on the mid-western coastal plain running into rolling and more hilly land in its southern portion, facing the Gulf of Paria. Prior to 1920 there was a considerable number of small factories, but during the past 30 years progressive centralization of manufacture, together with the practice of mechanical methods in the field, have brought about a high degree of efficiency. Until the new Monymusk Factory was erected in Jamaica, Trinidad had the largest sugar factory, the St. Madeleine, in the British Empire. A high proportion of the sugar-cane ground by the eight factories now in operation is grown and supplied by cane farmers, their relationships with factories being controlled by the Cane Farming Control Ordinances. Fanners' holdings range from a fraction of an acre to over 500 acres each, and they supply a considerable but varying proportion exceeding one-third of the total crop manufactured into sugar. The number of cane farmers varies greatly from year to year, ranging from just over 10,000 to well over 20,000 in different years, depending upon the attraction and remuneration available from other occupations, such for example as the oil industry which is centred near to and to the south of the cane areas.

For many years intensive research into the varied problems of sugar-cane production has been conducted by the Department of Agriculture, the Imperial College of Tropical Agriculture and the Sugar Manufacturers' Association. Mosaic disease is not important but the sugar-cane frog-hopper (Tomaspis saccharind) causes heavy losses, and until recently was found extremely difficult to


control. The discovery of modern insecticides such as Gam¬ mexane and D.D.T., and their application to the control of this pest now offer what is an apparently satisfactory solution. The serious effects of frog-hopper infestation may be judged from the fact that in some years it was responsible for an annual loss of cane over parts of the cropped area amounting to no less than 10 tons per acre. Minor damage is caused by moth borers and other insect pests.

The Trinidad sugar industry has played a leading part in the application of mechanical methods to field operations including drainage, and one estate, Woodford Lodge, has given its name to a system of land management involving the use of cambered beds, with a special ploughing technique, and inter-row cultivation by the rotary hoe. The average annual rainfall is about 63 in. but as in other islands it varies from year to year, the maximum and minimum over a 20-year period being 90 in. and 45 in. respectively. Replacement of older varieties of cane by new ones produced at the Barbados Cane Breeding Station has taken place and is still continuing.

British Guiana Although British Guiana is not considered to be a part of the

British West Indies, it naturally falls within the compass of a descriptive account of sugar in the colonies of the Caribbean area. Situated on the mainland of South America, to the south-east of Trinidad, it is 83,000 sq. miles in extent. The sugar-cane lands are on the coast, which is to the north-east, and comprise a strip of low-lying areas reclaimed from the sea and from swamps fed by five rivers which discharge into the Atlantic Ocean. Extensive sea walls give protection from the encroachment of the sea, while dams, drainage canals, sluices and pumps control the influx of fresh water from the interior. The cultivated area is in these respects similar to the fens of England, and the reclaimed and drained areas of the Netherlands. The soil thus won by persistent and continued effort is highly fertile. Sugar production in all its stages involves an unremitting contest with water. Two levels of waterways are maintained by an intricate canal system, the higher canals being used for irrigation and transport and the lower for drainage. Apart from the sea and the inflow of fresh water from


the interior, the heavy and varying rainfall necessitates provision for the removal of excess water. While a few estates can drain by gravity to the sea or to the rivers at low tides, costly pumping equipment is required by most of them, and though pumping lifts are low, immense volumes of water have to be moved. It has been estimated that each square mile of cane cultivation needs almost 50 miles of drainage canals and 16 miles of high level channels, a total of some 5,000 miles for the entire cane lands of the Colony. Apart from the expense of pumping, heavy annual expenditure is involved in cleaning the water system of each estate and the maintenance of the dams. Indeed sugar-cane production in British Guiana may well be called an amphibious operation.

Mechanization of land preparation and cultivation has become normal practice. Sugar yields have increased as a result of improved methods and the application of the results of research as well as by the growing of better cane varieties. Until recently cane breeding was carried on in the Colony, but now the industry participates in the work of the cane breeding station in Barbados, where special attention is devoted to the particular and exacting requirements of the most unorthodox sugar country in the world.

The total area in cane cultivation is about 70,000 acres, of which between 70 and 80% is available for harvesting each year, yielding slightly more than 3 tons of sugar per acre. As in Trinidad, the cane is fired before being reaped. It is carried by head-load to the high level canal banks and there put into punts for transport to the factory. " T r a i n s " of punts are hauled by mules or rubber-tyred tractors, the whole of the crop being waterborne. In general, factory efficiency is good, and is being further improved by modernization.

The Dominican Republic The Dominican Republic is 19,300 sq. miles in extent, and

forms the western two-thirds of the island of Hispaniola, between Puerto Rico to the east and Jamaica to the west. Sugar-cane was introduced there by Columbus on his second voyage in 1493. The annual production of sugar is now about 500,000 short tons, and there are 14 factories, of which 4 account for more than three-fifths of the total. About 15 % of the cane milled is supplied by colonos (farmers). Cane is grown under natural rainfall, except


that Barahona in the south-west uses irrigation, the cane produced there annually being over 600,000 short tons. The main sugar zone is to the south-east where some 250,000 acres of the total of 300,000 acres are devoted to the crop. Mechanization of field work is rapidly extending, the large estates being almost completely mechanized. Manual labour and animals are still largely used in some areas for certain operations including cane haulage. Cane and sugar yields are comparatively low, and in past years there has been little or no use made of artificial fertilizers, though pen manure (f.y.m.) and factory residues are applied to the land. Fertilizer studies are being conducted on an increasing scale, notably at Ozama and La Romana. The Ozama Sugar Company and the Central Romana Corporation (operated by the South Porto Rico Corporation) contribute to the B.W.I. Central Sugar Cane Breeding Station. They already have several Barbados varieties in commercial cultivation, and others are under observation. P.O.J.2878 and other Javan varieties are extensively grown. Among the many varieties are Puerto Rican and Co. canes. Mosaic disease is serious, and out of control, as in Jamaica.

Alluvial soils at Ozama which fall into Turner's Group IV are being cultivated on the cambered bed system with 24-ft. beds carrying 4 rows of cane on 6-ft. spacings. Drains between the b e d s are formed with a Cuthbertson ditcher. Contour cultivation on calcareous slopes has been introduced. Fields at La Romana a r e of 100 acres divided into 20 acre portions. Some 10,000 acres a r e ploughed annually on this plantation, mainly by heavy tractors w i t h notched disc ploughs.

Planting is done by hand, and inter-row cultivation largely in t h e same manner. Animals and light tractors are also used. Pre¬ emergent weed control using 2-4D is successful but not yet extensively conducted. Five or more ratoon crops are reaped b e f o r e replanting. Reaping and loading are done by hand in most p l a c e s , though mechanical loading is gradually being adopted to a l i m i t e d extent. Cattle haulage to tramway, plantation railway or f a c t o r y is the most common method of field transport. Thirty-inch g a u g e railways are generally used though there are some 50 cm. Decauville track, and extensive standard gauge systems, one of w h i c h has 144 miles of track. Portable track is used to some extent w i t h the light railways.


Mexico Sugar production in 1950-51 amounted to 665,714 metric tons,

when there were 83 factories operating in 16 States. The State producing the largest amount is Vera Cruz with 45% of the total. Excluding 4 south-eastern States with only 2% of the output, the other 12 had a total area of cane cultivated amounting to 164,584 hectares of which 151,194 hectares were harvested. The total cane ground amounted to 7,454,828 metric tons with an average yield of 49.3 metric tons per hectare. The Government through the Ministry of National Economy controls all industries that use sugar-cane as a raw material.

South America Peru

Cane is cultivated in the irrigated, almost rainless, coastal lands. Annual production of sugar is about 450,000 tons of which nearly one-half is exported to S.A. markets. Guano from the uninhabited islands off the coast is used as fertilizer. River water is distributed under Government control from the high valleys through canals and regulating works. During the dry months the gravity supply is supplemented by pumped water from wells. Climatic and growth conditions make it possible to operate the eleven factories for 10 months or more each year. Cane is burnt for harvesting. Cane is mainly reaped manually, but labour shortage has led to mechanical cutting with modified tractor-dozers. Transport is entirely by light railway and portable track, using steam locomotives on the permanent line.

Brazil The cane sugar industry of Brazil is located in the northern

provinces, and is centred on Pernambuco. The area cropped annually is about 335,000 hectares (828,000 acres), yielding some 12 3/4 million metric tons of cane, equivalent to 38 metric tons per hectare (15 long tons per acre). Internal consumption of sugar has increased and exports are likely to cease entirely. The cane sugar zone suffers from occasional severe droughts which cause considerable variations in output from year to year. The average yields could be greatly increased by improved farming methods (Fig. 5) and control of pests. The mealy bug, Margarvides


carvalhoi, which lives on the root system, causes heavy loss by necrosis of the roots, known in Pernambuco as "Sugar Foot Rot." The moth borer, Diatraea saccharalis, is under satisfactory natural control in Pernambuco, particularly by Trichogramma minutum, but causes extensive damage in the adjoining state of Sergipe to the south.

There are more than 22,000 small sugar factories with capacities up to 300 tons yearly, and some 270 having an average of about 3,000 tons. Many of the factories are equipped to manufacture fuel alcohol direct from the cane juice alternatively to sugar, in accordance with market requirements.

Argentina The cane sugar industry is carried on in the provinces of

Tucuman, Jujuy, Salta, and other areas of the littoral, most of the sugar being produced in Tucuman where 26 of the 37 mills are situated. Extensive research on the agricultural problems of sugar-cane is conducted at the Agricultural Experiment Station, Tucuman. Production in 1951 was 622,800 metric tons of sugar from 250,300 hectares of cane.

Indian Union The total area devoted to sugar-cane in 1948-49 was reported

to be 3,645,000 acres. The Industry is mainly concentrated in the Uttar Pradesh and Bihar, which together account for nearly 2 3/4 million acres. Yields are generally very low except in limited areas. The overall average is between ro and 12 tons of cane per acre, though 30 to 35 tons per acre have been reported.

One hundred and thirty-four factories, which produce sugar direct from cane, crushed just over 10 million tons of cane which yielded approximately 1 million tons of sugar. By far the greater portion of the cane produced is used for making gur of which the calculated net consumption amounted to 3,169,000 tons in 1948, more than one-half of which was made in U.P. Apart from the low yields of cane, the method of making gur, which is concentrated cane juice, is very primitive and yields an average of only 1.37 tons per acre of this impaired form of sugar, equivalent to nine-tenths of a ton per acre of 96º sugar.

The sugar industry of the Indian Union is second only to cotton and there are 20 million cultivators engaged in it. Cost production

30 AGRICULTURE OF THE SUGAR-CANE I

of sugar-cane is uneconomically high, and great endeavours are being made to lower it, and to increase the cultivator's profit. Intensive methods for cane production are receiving attention because of the policy of the Indian Union of increasing supplies of food grains.

Research and Extension Services The Indian Central Sugar Cane Committee recognizes the need

for research and instruction. The Coimbatore Research Station, where cane breeding and much related work has been so successfully conducted, will be supported by a chain of research stations for the testing of new canes. Combined with a programme of inspection, advisory and supply services, the adoption of practical methods, which have been evolved for protection against diseases and insect pests, and the practice of improved agricultural methods are expected to bring about higher acreage yields and general improvement in the Industry.

The more serious problems of the small cultivator appear to be the control of pests and diseases. In the U.P. the diseases of major importance are red rot, wilt, smut, stinking rot, mosaic, red stripe and yellow spot, the causal organisms of which are recorded in J. P. Martin's List (I.S.S.C.T. 1950).

In the Bombay Province some irrigation is practised and Trichogramma minutum has brought about a marked reduction in borer infestation. In Bihar a reduction of the cattle population during the war years caused a set back to the Industry. The factory estates are now hiring tractors and implements on a limited scale to growers. In the U.P. a campaign is being actively prosecuted for better agricultural methods. Healthy seed and disease resistant varieties are being distributed, and field inspection with prompt control of pests and diseases is being conducted. The water available for irrigation is being increased by the provision of additional wells and water lifting equipment. Similar action is being taken in the Madras Province, where 25,000 implements had been distributed up to 1951.

Java The island of Java, 50,390 sq. miles in extent, is in the North

Indian Ocean between 105° and 115º east longitude. The population density exceeds 900 per sq. mile. The soils are of recent


volcanic origin, varying from heavy clay to light sandy loam, and are highly fertile. Sugar-cane is grown in the eastern and central districts, being chiefly confined to areas which experience a dry season extending to four months of the year. Most of the cane lands are irrigated by gravity water. The cane is grown after rice (paddy) in land leased from the native owners, and is confined to the plant crop only. Prior to the last war the industry was highly efficient, and heavy yields were obtained, amounting to 9 tons of sugar per acre on some estates. In 1930 production reached 2,969,269 metric tons of sugar from 198,671 hectares of cane, but marketing difficulties brought about by the reduction of imports of sugar by India caused a decline, and production had to be reduced. There were 176 factories in operation in 1932, but these had fallen to 35 in 1936, when only 85,700 hectares of cane were harvested yielding 592,000 metric tons of sugar. There was a temporary recovery followed by disaster caused by the entry of Japan into the war in 1941, and the Indonesian revolt, from which the island has not yet recovered.

The industry as it existed before these events demonstrated the successful application of science to sugar-cane production in a remarkable manner. An experiment station for Central Java was established in 1885, quickly followed by others for West and East Java in the next two years. At that time the industry was experiencing grave economic difficulties, to which was added the effect of "Sereh" disease. In the succeeding years the work of these stations was gradually co-ordinated until in 1924 it became centralized at Pasoeroean. In the 1930s this Experiment Station for East Java (Proefstation Oost-Java) was regarded as the outstanding research station for a tropical crop. Research conducted there has profoundly influenced the industry not only in Java but throughout all countries in which sugar-cane is grown. The aspect of the work which has attracted most notice is cane breeding, originally begun in 1893 with the object of producing a cane resistant to Sereh. This led to the selection of P.O.J. 2878, recognized in 1921 as possessing superior qualities. By 1930 this variety occupied 98% of the total area under cane in Java, and soon became widely distributed for commercial planting in other countries because of its remarkable vigour and resistance to Mosaic disease. It has also been used as a parent for breeding


work at other stations, which has resulted in producing new high¬ yielding varieties.

Java now forms part of the independent state of Indonesia. The cane sugar industry has been gravely affected by the disturbed conditions of recent years, and production is far below pre-war levels. Problems of pest, disease, and weed control have greatly increased as a result of neglect during that period. The research station at Pasoeroean suffered the loss by wanton destruction of its priceless records, but its work is being continued. There is evidence of gradual recovery but the industry continues to face serious difficulties. Sugar production in 1949 was 223,300 metric tons. Two years later this was almost doubled. The estimated output for 1952 is 475,500 metric tons.

The Philippines The Philippines form a group of 7,090 islands having a total

area of 115,600 sq. miles, situated between 116º and 127º east longitude in the northern tropics, about 500 miles from the southeast coast of Asia. The n largest islands total 10,700 sq. miles. The cane sugar industry is concentrated mainly in Negros and Luzon. The Japanese occupation during the period from early 1942 until the end of 1944 gravely affected sugar production, which has since been restored to its pre-war proportions of nearly 1 million tons output yearly. There is a considerable quantity of muscovado and low grade sugar made in addition. In 1938 there were 6,753 muscovado mills with a total output of about 52,000 tons. The total area under cane is about 200,000 hectares (450,000 acres). The principal variety grown is P.O.J.2878.

Taiwan (Formosa) This island in the China Seas is 13,944 sq. miles in extent, and

consists mainly of mountainous forest lands. Sugar-cane is grown in the coastal lowlands, where the soils range from sandy alkali land to dry heavy clay. The sugar industry has been in existence for several centuries, the first exports being recorded in 1624. Occupied by the Japanese in 1895, Taiwan again became part of the Chinese Empire fifty years later. Sugar production amounted to 1,024,563 tons in 1937-38, when some 270,000 acres were devoted to the crop. As in Java and the Philippines, immense


damage to the industry occurred during the recent war. Reconstruction has involved extensive rehabilitation of the cane fields and factories. There are now 35 of the latter with a total daily crushing capacity of 69,400 metric tons of cane.

In 1946 the Chinese embarked on organized research for the sugar industry, devoting prior attention to cane breeding and the testing of new varieties. The western side of the island has poor soils and is exposed to strong monsoon winds. These conditions make it necessary to grow a hardy cane, such as N : Co 310, which was introduced from Natal in 1947, and shows promise after extensive trials though it is susceptible to Mosaic. In the more protected lands, particularly in the east P.O.J. 3016 is widely grown, but the need is felt for new varieties more suitable to difficult areas, and resistant to diseases of which the major ones are Mosaic and Red Rot.

Australia The cane sugar industry is almost entirely concentrated in the

state of Queensland, about 4% of the total production coming from the northern part of New South Wales, where there are three small factories having a total output of about 44,000 tons of sugar. This area is about 30º S. the climate being rather cool for cane ; the rainfall is 50-60 in. a year, and most of the cane is cropped at 2 years. The cane is transported by barges to the factory. The total area of N.S.W. and Queensland devoted to cane is approximately 450,000 acres, comprising over 8,000 farms. About two-thirds of the total acreage is harvested annually, the canes being reaped at 12 to 17 months. The area harvested for milling in 1948 was 285,585 acres producing 7,205,583 short tons of cane, from which 1,019,082 short tons of sugar of 94 net titre were made.

The sugar-cane areas of Queensland are north of Brisbane in widely separated districts terminating beyond Mossman, about 1,100 miles from Brisbane. Field operations are highly mechanized, implements and tractors being of lighter types than are used in most other countries. Great ingenuity has been disayed in the design and adaptation of agricultural machinery for sugar-cane cultivation, reaping and transport. About 8% of the total cane harvested annually is reaped mechanically. A variety of loading equipment is used. Transport to the mills in Queensland


is mainly by light railway, the total length of line owned by the milling companies being about 2,000 miles.

About 72% of the total sugar crop is derived from cane grown under natural rainfall conditions. Irrigation is used in the Lower Burdekin and Bundaberg districts, each of which produces about 14% of the total. The incidence of pests and diseases varies remarkably in the different districts. Quarantine measures are taken to control new introductions of cane, which may only be made by the Bureau of Sugar Experiment Stations. Local quarantine areas have been proclaimed with the same object—the prevention of the introduction and spread of diseases.

The following description of the general agricultural practices in Queensland has been compiled from a private communication from Mr. E. G. Baber.

Crop Cycle and Preparation The usual crop cycle consists of a plant and two ratoon crops

followed by a fallow of 5 to 8 months. In certain areas with rich soil and adequate rainfall 3rd, 4th and sometimes 5th ratoons may be grown. Most soils are naturally well drained, drainage being assisted by the deep cultivation given by the grubber. When main drains are necessary they usually follow old water courses. Fields thrown out for replanting are usually ploughed in October or November and sown with a green manure crop, the principal of which is one of several varieties of cowpeas, Vigna unguiculata, crotalaria or Mauritius bean being used to a limited extent in certain areas. The green manure crop is ploughed in at the end of the wet season, usually in March, and the fields are disc harrowed, ploughed and disced again. Grubbing (sub-soiling) to a depth of 15 in. before the final harrowing is widely practised. Tractor¬ drawn disc ploughs with two or three 28 or 30 in. discs are generally used. Harrowing is done by tandem disc machines. Plain discs are being replaced by the notched variety. Rigid tine or diamond harrows are also used.

Planting The time of planting depends upon the close of the wet season,

usually at the end of March or early April, planting being continued from then until about the end of August. Endeavours are made to complete planting before the beginning of June, but if


this is not possible the work is continued in July and August, June being the mid-winter month is usually too cold for planting. Both machine- and hand-methods are used, the former being conducted by the use of a cut ter planter of which there are several types varying with the method of cutting the setts and of stacking the stalks in the trays of the machine (Fig. 57). The knife is usually of a revolving or reciprocating type, but in more recent designs a fixed knife is used. These planting machines are loaded with whole stalks from which the tops and trash have been removed. The machine cuts the cane into setts, opens the drill or furrow, plants the sett, drops the fertilizer, covers, and if required can be fitted with a rear roller to press d o w n the soil. Both one and two row planters are used. Older machines do not have the cutter attachment, but carry out the s a m e operations, except that the setts are cut by hand or small circular saw and hand-fed into the planting chute. The usual method of planting by hand is to cut a furrow, lay the complete cane stalks in the furrow, and cut them into setts in that position, covering up by harrow or plough.

Weeding and Ferti l izing Inter-row cultivation is highly mechanized. High clearance

tractors with tool bars carrying various types of tool are used. Rigid tines with points of various shapes ranging up to large sweeps, and 16-in. discs are used. Weeding in the rows is carried out one or two rows at a time by large spring weeder tines attached to the tractor tool bar. Horses are still used on some farms, and weeding carried out by disc harrows of the Cotton-King type with a gang of four discs on each s ide of the row, and weeder tines for weeding in the row. Various other types of weeding implements are used including rotary machines which remove small weeds and excessive soil from the cane row. Practically all plant cane receives 4 to 6 cwt. per acre of complete fertilizer placed in the furrow at t h e time of planting. The mixture is usually low in nitrogen, t h e phosphate and potash being varied according to soil requirements. Three mixtures of different compositions are used. Nitrogenous fertilizers are usually only applied to plant cane when the green manure crop has failed. A common practice for ratoon fertilization is the application of 2 to 5 cwt. per acre of sulphate of ammonia.


Ratoons Cane is burnt for harvesting, and the residues remaining on the

field are raked into rows and again burnt to facilitate the use of cultivation implements. Various methods are employed for ratoon cultivation and stubble shaving is carried out in some places, rotary hoes being used in the inter-row. Grubbers are sometimes used to a depth of 12 to 15 in. between the rows, followed by the usual work with disc harrows and weeding implements. Three other methods are:—

(a) A furrow is ploughed away from each side of the row, the middles then being split and the soil thrown back on to the row, with subsequent normal cultivation.

(b) The first two operations of (a) reversed. (c) A rotary hoe with the two middle hoes removed straddles

the row.

Pests and Diseases White curl grubs are serious pests of sugar-cane. There are

three important species:—the greyback beetle (Dermolepida albohirtum), the frenchi beetle (Lepidiota frenchi) and Pseudo¬ holophylla furfuracea. All of them are completely controlled by the use of benzene hexachloride applied to the cane row before the commencement of beetle flight. Wire worms (Lacon variabilis) and the black maize beetle (Heteronichus sanctae-helenae) are also readily controlled by the same insecticide. The rates and method of application vary according to the species it is desired to control.

Rats are the main animal pest and it has been found possible to control them by systematic poisoning campaigns. The most effective poison used is thallium sulphate treated wheat placed in paraffined paper bags. Zinc phosphide baits are also used with almost equally good results.

A number of important diseases still cause considerable loss. Mosaic, Fiji and Downy Mildew disease are controlled by roguing; leaf scald, and ratoon stunting disease by the use of clean seed. Resistant varieties remain the easiest and most effective control measure, particularly in the case of diseases such as red rot which depends so much on weather conditions. All varieties are therefore tested for their reaction to the major diseases and only the resistant ones released for commercial growing.


Reaping and Transport in Queensland The harvesting season usually extends from early June to mid-

December. Harvesting is done by contract. A ganger contracts with a grower or group of growers to harvest their cane, usually totalling from 3,000-6,000 tons. The ganger is responsible for obtaining sufficient cutters to complete his contract. The average rate per man per day is about 7 tons of cane cut and loaded on to trucks, though this quantity varies from as much as 13 tons to less than 3 tons per day.

Transport to the mill is by locomotive and 2-ft. tramline. The grower is responsible for delivering the cane to the permanent line and this is done either (a) by portable line running into the cane fields from the main line, or (b) by means of rail cars moved between field and main line by motor trucks.

Method (a) The portable rail is moved across the field as necessary by

the cutters, 16-22 rows being cut for each shift of the line. The grower is responsible for laying the rail from the main line to the field, as well as the head line and curves in the field. He is also responsible for hauling empty and full cars from and to the main line.

(b) One or two empty rail cars are transported by motor truck to the field. The cars are lowered to the ground, loaded, hauled back on to the motor truck and returned to the main line.

FIJI

Situated in the southern tropics, Fiji consists of a group of some 250 islands, of which the two largest are Viti Levu and Vanua Levu. There are four sugar factories in the former and one in the latter, the whole being owned and controlled by the Colonial Sugar Refining Company of Sydney, Australia.

The average annual rainfall on Viti Levu ranges from 69 to 82 in. in the north and north-west, and 116 in. at Nausori in the south. In the sugar belt of Vanua Levu the rainfall is about 83 in. per annum.

The total area devoted to sugar-cane in the two islands mentioned is about 95,000 acres. The crop is grown mainly by Indian


small farmers, who are tenants of the Company in land by f a r the greater portion of which is leased from the Government of Fiji. Individual farms are 10 to 12 acres in extent, divided in to four approximately equal portions, one of which at any time is in young plants, one in plant canes, one in first ratoons and one in fallow. Green manure crops are planted after first ratoons have been reaped and ploughed out, the legumes grown being Maur i tius bean, Stizolobium aterrimum ; Cow pea, Vigna catjang ; a n d Pigeon pea, Cajanus indicus. One ratoon crop only can be grown because of the prevalence of the serious Fiji disease, first recognized in 1907, which is most damaging in fertile lands. Irrigation is n o t practised. The cane is conveyed to the factories by 24-in. gauge light railway using portable track in the fields except for a portion which is transported by river to the Nausori Mill.

Mauritius An island in the southern tropical region of the Indian Ocean in

longitude 57º E. and latitude 300 S., Mauritius has an area of 720 sq. miles of which more than one-third is devoted to sugar-cane. The topography and climate vary considerably from the coastal plains to the central plateau. Mountain peaks approach 3,000 ft. in height. Rainfall ranges from about 50 in. per annum in the north and west coastal plains to more than 100 in. in the plateau, being an average of 124.4 in. at Curepipe (1,800 ft.) where the mean temperature is 67.5°, compared with 77.5° at sea level. The island is subject to cyclones which sometimes cause extensive damage. The loss of sugar production attributed to these high intensity storms may amount to one-half of the crop, as it did in 1945, though if severe damage does occur it is usually much less. Occasional droughty years are experienced which also reduce cane and sugar yields by 10 to 20%. The combined loss by drought and cyclone in 1939 was estimated at 27% of the crop.

The fertile volcanic soil, and the climate are generally well suited to the cultivation of sugar-cane. Five or six ratoon crops are grown, the average yields of cane being about 24 metric tons per arpent (22.6 long tons per acre) and of sugar 3 metric tons per arpent (2.83 long tons per acre). The area under cane and harvested, with yields in 1950-51 are shown in the table.


Research on sugar-cane conducted in Mauritius has made notable contributions to improved agricultural practice, the study of fertilizer problems, and the production of new hybrids, all of which have advanced the interests of the industry there, and have contributed to improved field practice and yields in other countries. The Sugar Research Station, a division of the Department of Agriculture, conducts cane breeding work and general investigations of sugar-cane problems. Among outstanding achievements of recent years is the variety M. 134/32, a vigorous rich cane with high resistance to diseases, which now occupies 95% of the total area planted. The strong root growth of this cane has brought about virtual control of the beetle Phytalus smithii, the grubs of which are destructive to cane roots, by its capacity for rapidly replacing damaged roots. The sugar industry maintains a laboratory for the determination of the fertilizer requirements of sugar-cane by the method of foliar diagnosis.

The table shows clearly that yields of cane from farmers' lands are low in comparison with those of estates attached to factory organizations. In this respect conditions are similar to those in Jamaica and other parts of the West Indies.

Natal Location of the Industry

The industry is localized in the coastal lands of Natal ranging for 200 miles from Port Shepstone in the south to Mtubatuba in the north (Fig. 6). This zone of undulating and hilly land, with occasional alluvial flats which increase in area towards the north, never extends to more than a few miles from the sea. The total area devoted to cane now exceeds 400,000 acres, of which about one-half is harvested each year. In 1950-51 the area harvested was 220,500. At the end of 1949 there were some 80,000 acres of virgin land suitable for sugar-cane within the existing sugar belt. The development of new lands to the east and north is

D


under active notice. The rainfall averaging about 41 in. per annum in the sugar belt is low in comparison with other places not dependent on irrigation, but the cane displays remarkable vigour and sugar yields are good. South of the Tugela River which is the southern boundary of Zululand, most of the cane, both plants and ratoons, is cut after 18 to 24 months' growth. North of the Tugela, plant crops are reaped at 14 to 18 months, and ratoons at 12 to 14 months. It was recently stated that there is an increasing tendency to average two crops in three years, as compared with three crops in four years in other countries. In most areas there is a severe check to growth during the cool or winter season, from June to September. A great advantage is the long milling period extending to nine months.

Soil Conservation Contour planting is the general rule, a system which provides a

highly important safeguard against erosion, and greater convenience for harvesting and transport. Soil erosion is a gravely serious problem in South Africa, and the protective qualities of sugar-cane are well appreciated as a contribution to soil conservation. The land is left unprotected by a growing crop for as short a time as possible between the reaping of the last ratoon and replanting with cane. During this period green manure crops are grown and ploughed in. The principal legume used for this purpose is Sunn Hemp (Crotalaria juncea).

Irrigation During recent years irrigation has been introduced in some

areas. The Natal Estates Ltd. own the most extensive system, covering 12,000 acres.

In other districts overhead irrigation is used to a limited extent, but it appears that the need for further investigation into rates of application, costs and financial returns is recognized before any extensive development of this method can occur.

Cultivation Field operations are highly mechanized. The uncertain and

apparently diminishing supplies of agricultural labour have stimulated interest in the use of machines, some of which have been designed and built locally, such as mechanical cane planters.


Tractors range from heavy-track type to light-wheeled machines with corresponding variation in implements. Attention is being devoted to mechanical reaping. A prototype machine capable of working on sloping land has been constructed and tested. Mule-drawn light implements are largely used for weeding and inter-row cultivation after the cane has become established.

The European growers or farmers form the South African Cane Growers' Association, 720 members of which supplied 3,170,700 tons of cane to the mills in the 1950-51 crop, an average of 4,400 tons per grower. There are also non-European growers who delivered 434,000 tons.

Cane Varieties From the earliest days of the industry the subject of cane

varieties has been of vital importance. Its establishment with imported varieties developed into a period during which the China cane, of unknown origin, was predominant among some 50 varieties introduced by the Government in co-operation with farmers' associations. Smut disease became serious, and in the '8o's the "Uba " cane, brought in with others, proved so vigorous and free from disease that it rapidly became the principal cane grown, despite other unfavourable characteristics. Although the search for better types continued unremittingly, Uba retained its position for a great many years.

In 1902 the Natal Department of Agriculture, realizing that it might be necessary to replace Uba, made numerous importations from various places. A system of plant quarantine became effective in 1913 to protect the rapidly growing industry against introduced disease. A few years later Mosaic disease, which had caused grave damage in other countries, was recognized in Natal, only Uba being free. This further stimulus has contributed to the present variety outlook. In 1923 the South African Sugar Association decided to set up its own research organization, which was established at Mount Edgecombe in 1925, with the principal object of introducing and testing new varieties of cane in a scientific manner. The work of this station has been a major contribution to the progress of the industry in many ways, particularly in regard to improved commercial varieties.

The need for greater care in effecting importations of new


varieties became apparent and, in 1925, a quarantine glasshouse was built in the Botanic Gardens, Durban. All imported canes are grown there for two generations, being then released to the Sugar Research Station if they have not displayed symptoms of disease.

Cane Breeding For several years the experiment station used imported plant

material which had passed through the quarantine station for all its varietal investigations. The range of suitable new canes available was, however, so restricted that cane seed (fuzz) was brought in and large numbers of seedlings grown for selection. At that time local breeding work could not be conducted because canes in Natal did not produce seed though they flowered freely. After close study this was found to be due to the non-development of the pollen, which, though present, was incapable of fertilizing the female flower. Research revealed that the limiting factors were temperature and humidity, and that when these were maintained between the most favourable limits controlled crossings could be successfully made.

Final selections are released for commercial planting after being approved by the Department of Agriculture and the publication of a notice in the Gazette.

The position in regard to commercially grown varieties has completely changed during the past 25 years. The overwhelming predominance of Uba has given place to Coimbatore varieties introduced as cuttings, which in turn are being abandoned in favour of N:Co-310, a cane raised in Natal from fuzz which originated at Coimbatore.

Provision for Research In addition to the work described, which is conducted by the

botanical division, the experiment station includes divisions of agricultural chemistry, plant pathology, entomology and agronomy. Headquarters are at Mount Edgecombe, where there are extensive well-equipped laboratories and glasshouses with offices, library and staff residences, on 100 acres of land mainly devoted to the growing of seedling canes. At Chaka's Kraal, 20 miles to the north, the station has a 200-acre farm where the testing and


propagation of promising seedlings are carried on and plantings made of final selections for commercial distribution. Because of the rapidly expanding work, it has become necessary to obtain 300 acres of additional land for the growing of these final selections on a much larger scale so that greater quantities of plant material of approved new varieties can be made available for planters, who will pay for it at a fixed rate per ton.

In June, 1951, the foundation stone was laid of the laboratories for the Sugar Milling Research Institute, established in 1949. This institution is jointly financed by the South African Council for Scientific and Industrial Research and the Natal Sugar Millers' Association. I t s work is to investigate milling practice and to conduct research on problems of cane sugar extraction processes in Natal.

Organization of the Industry The industry is composed of numerous groups having their

interest in the prosperity and progress of sugar production. The whole organization with its various associations provides for full discussion and consideration of all problems and for the settlement of differences by agreement wherever possible, or if not, by the decision of an independent umpire, Each section has its own representative body linked directly or indirectly with the South African Sugar Association, which is in effect the central government of the industry. There is complete regulation of production by a quota system. This and other controls, such as statutory agreements relating to prices paid to farmers, are effected under the provisions of the Sugar Act.

CHAPTER 3

THE PLANT AND ITS PROPAGATION

THE SUGAR-CANE

Description of the Plant Though all sugar-canes are members of the great family of

grasses, there are remarkable variations in the size, general appearance and habit of growth of different varieties. Some of the wild canes are slender with fine narrow leaves and are closely similar to the taller grasses, while commercial canes used for the production of sugar have thick stalks, broader leaves and extensive root systems.

A description of the plant from the point of view of the planter may well begin with the stalk or stem which consists of a succession of joints or nodes spaced at intervals and separated by what are called internodes. At each joint or node is a bud, successive ones appearing on opposite sides of the cane stalk. Growing from the lower part of the joint is the leaf sheath which completely surrounds the stalk for a distance of several inches up to about a foot in an upward direction before it develops into the characteristic leaf blade. The sheath is in the form of a cylinder severed vertically down one side, the bud being contained within the sheath on the opposite side to the vertical opening. The sheath is therefore attached to the stalk by a basal ring clearly visible as a slightly thickened part of the joint when the leaf sheath is removed. Immediately above this are rings characterized by a number of light-coloured spots which are embryo roots, called the root or growth band (Fig. 7).

The distance between the joints, i.e., the length of the internode, varies considerably even with the same variety of cane under different conditions. If the cane is subject to drought or continuing cool weather, growth is arrested and the distance between the joints decreases. When conditions favourable to growth return, this distance, that is to say, the length of the new internodes, increases. It is, however, one of the characteristics of the different

44

THE PLANT AND ITS PROPAGATION 45

varieties under normal conditions of growth. Some canes display a staggered arrangement of successive internodes each being set at an angle to the other giving a zigzag appearance to the stalk. As a general rule types of cane which have comparatively long internodes and straight stalks are preferred.

The stalk is more or less cylindrical, with an outer rind varying in hardness with the variety of cane, and consists internally of softer tissue, comprising fibrous ducts and their walled cells. The fibres are bundles of extremely fine tubes some conveying plant foods in solution from the roots to the leaves, and others carrying the juice, with the dissolved sugar and other products synthesized in the leaves to the cells in the stem. The nodal portions are much tougher than the internodes. The surface of the stem is coated with a thin protective layer of waxy material which varies in amount with the type of cane, and is moisture resistant.

Varieties differ considerably in the extent to which the leaf sheaths adhere to the stalk as growth proceeds. In some, as the older leaves die and dry up the sheath becomes loose on the stalk and breaks away easily at the point of attachment. Canes of this type are said to be free trashing. Others retain the older leaf sheaths more firmly, with the blades attached. This feature is undesirable in very wet conditions because water collects at the base of the leaf sheath, and if wet weather persists the buds may grow and roots develop. Where the moth borer is a serious pest the persistent leaf sheath protects the eggs and the caterpillars which develop from them against access by natural enemies, whether these are bred for distribution in the cane fields, or normally present as part of the biological population. At the same time certain varieties which are retentive of their trash in this way are vigorous, heavy yielding, rich canes, advantages which outweigh the drawbacks caused by the absence of free trashing.

The Roots

The root system of the cane consists of comparatively thick buttress roots which may be seen at the base of the stalk. These help to support the cane but play little or no part in supplying nutrients. The root system proper consists of a mass of small roots confined mainly to the upper 12-in. layer or so of the soil, with some which penetrate to depths of 10 to 12 ft. or more under


some conditions. This principal root system of the cane provides the means by which the plant obtains through the root hairs supplies of food for growth and development. A healthy, vigorous and strong root system is a desirable characteristic of cane for the support of the plant as well as for the ample supply of food requirements. Varieties of cane show differences in the vigour and extent of their root systems, and as mentioned elsewhere some shallow rooting varieties are easily blown over in wind storms, while the vigour of others enables attacks by root damaging pests to be defeated by the rapid development of new roots.

Flowering The stalk terminates at the upper end in a whorl of developing

leaves and a growing point, which under certain conditions develops into a slender arrow bearing a tassel of tiny flowers very similar to an enlarged edition of the seeding heads of some grasses (Fig. 10). The ability of cane to flower and to produce fertile seed is important for cane breeding work, but is an undesirable characteristic in commercial canes, since the appearance of the arrow and tassel indicate that the cane has completed its vegetative growth and is rapidly becoming mature. The conditions under which canes may be induced to flower, or by which flowering may be suppressed are being studied. In Hawaii for example it has been demonstrated that exposure of the cane to strong electric light for short periods during the night, at the period of growth when arrowing normally occurs, prevents formation of the flowering head and enables cane to continue growing, or in other words causes the plant to continue "making cane."

Function of the Leaves The complex processes whereby sugar is built up or synthesized

from the simple chemical compounds water and carbon dioxide, which are respectively taken up by the plant through the roots and the leaves, take place in the leaf under the influence of sunlight. The green colouring matter of the leaf, known as chlorophyll, plays a highly important part in this transformation. Agencies which damage the younger leaves, restrict their development, or destroy the chlorophyll can cause a stunting of the whole plant and a reduction in the amount of sugar produced.


Propagation The propagation of sugar-cane for the commercial production

of sugar is carried out by the vegetative method, i.e., by using portions of the stalk to produce new growths of cane. The type of cutting used, method of pre-planting treatment, and planting procedure are discussed later. For the present purpose the sequence of events in the development of a germinating seed piece will assist the planter to understand how cane is propagated, and the circumstances under which ratoon crops are produced (Fig. 8). Considering a single eye sett, the seed piece consists of a portion of young cane with an inch or so of internode on each side of the node or joint with its undamaged bud and embryo roots. Under favourable conditions of moisture and temperature the bud grows into a primary shoot, and the roots develop under the influence of growth-stimulating substances known as auxins, which are present in the seed piece. As the primary shoot grows it develops its own root system and a series of closely spaced joints each with its own tiny bud and embryo roots which in turn give rise to the secondary shoots thus producing the effect known as stooling or tillering (Fig. 9). The number of secondary shoots, each in turn capable of producing still others, determines the number of stalks of cane which together make up the clump or stool. The roots which grow from the original sett only suffice to support the developing bud until it can subsist on its own root system.

Ratooning When the cane is reaped there is still a portion of the stem or

stalk left underground, and it is this which gives rise to the succeeding growth of cane known as ratoons. The underground portion consists of closely spaced joints each with its complement of bud and root points, and the growth process of ratoons follows that of the original plant except that a primary root system is already present though this rapidly ceases to function as the new growth progresses. In order to stimulate ratoon growth from the lower portions of the part of the stalk left underground, stubble shaving is sometimes carried out by which the upper ends of the cane left after reaping are cut off at or just below ground level. This induces a sturdier ratoon growth and a deeper root system.


FIG. 9.—Development of secondary shoots.

Reproduced from the Queensland Canegrowers' Handbook by courtesy of the Bureau of Sugar Experiment Stations, Queensland, Australia

Planting Material Although the type of planting material varies from short sections

with two or three eyes up to the whole cane, and the density of planting from about 3,000 individual setts to the acre to double rows of cane laid in the furrow, there are certain basic principles which relate to the selection, treatment and placing of the planted seed material. In some cases where fields are planted during the harvest period, the tops severed from the reaped cane in the field are collected, trimmed, and used. Under favourable conditions these germinate quickly and produce vigorous growth. In Mauritius the propagation of cane in the course of plant breeding work is effected by the use of single eye seed pieces, thus completing the full possible range of portions of the cane used for planting.


Germination The term germination denotes the development of the roots of

the seed piece, the growth of the bud, and that of the roots from the base of the young shoot.

Clements found in Hawaii that good germination of single eye or one bud setts occurs but it is not generally convenient to use either these or two bud setts. The number of buds which germinate decreases when individual setts have more than three. When canes are placed horizontally in the furrow, the buds underneath germinate somewhat more slowly than those at the side or the top. It was found that setts from the upper third of 10 months' old plant cane were best, those from the middle and bottom being inferior because the older buds were more likely to have suffered injury. Investigations carried out by Cross gave best results from cane which was planted and covered immediately after cutting. If unavoidable delay has to be incurred the setts should be covered with trash and sprinkled with water. Germination and development are affected, amongst other things, by depth of planting which should be determined by experiment for the variety of cane and the type and condition of the soil. The depth of planting should not be confused with the thickness of the soil used to cover the setts. The depth of planting when the furrow method is used and the canes laid horizontally, refers to the depth of the furrow itself which is determined by the condition of the soil, the object being to ensure that the seed pieces are placed in a zone where adequate moisture is available. The setts themselves are covered with soil, lightly pressed down, to a depth of 1 to 3 in.

Preplanting Treatment The pre-planting treatment of setts is being practised to an

increasing extent for the control of diseases, particularly pineapple disease, caused by organisms which injure and destroy the seed piece before the bud can grow and roots develop. It has been found that setts treated with hot water at 52° C. for 20 minutes germinate more quickly and that the percentage of germinating buds is improved. McMartin conducted extensive investigations with a wide range of materials for the pre-planting treatment of cane setts in Natal, South Africa, where conditions are often adverse to the germination of the planted material. He found that


of all the methods used the most effective was to dip the cut ends of the seed pieces into 0.5 to 1 % Aretan solution, which was found to give complete protection against pineapple disease, and to improve the rate and extent of germination. A convenient strength is 1 oz. Aretan to 1 gal. (Imp.) of water. About 1 lb. of Aretan per acre planted is needed, the cost being negligible. A consequential advantage is the smaller amount of expenditure needed for supplying the replacing of ungerminated setts by fresh ones. Aretan is an organo mercurial, being methyl-ethyl-mercuric chloride. McMartin found Aretan to be the best of the organo mercurials tried and that of all the fungicidal materials tested only the ones containing mercury showed any promise.

Similar methods using other fungicidal treatments are successfully used in other countries, and the practice appears likely to extend. The high planting densities which in some cases amount to 10,000 setts per acre in Jamaica, about 8,000 being normal on most plantations there, are to a great extent due to the fact that all setts do not germinate even one bud of the normal three present on each seed piece. One object in using so much planting material is to avoid the necessity for " supp ly ing" or replacing setts which have failed to grow so as to ensure a satisfactory stand of cane. By the use of an effective fungicidal treatment combined with greater care in the selection of planting material considerable savings in the quantity of cane and labour required are possible.

CHAPTER 4

SUGAR-CANE SOILS

Agencies Affecting Productivity of Soils As might be expected of a member of the grass family, sugar

cane flourishes in a great variety of soils ranging from the windblown sands of the coast of Natal, to the heavy intractable clays found in parts of Jamaica and elsewhere. Each type requires its own particular form of treatment to enable it to produce profitably under the varying conditions of climate and rainfall, as well as special attention in respect of manurial additions and soil improvers. When natural rainfall is supplemented by irrigation, very heavy crops can be grown under the artificially created conditions thus induced, and similar soils may be found to react differently under the two environments even with other climatic elements practically unaltered. Methods of land preparation have changed within living memory from comparatively simple, gentle operations conducted in leisurely fashion on limited areas to the ripping, tearing, overturning forces applied by speedy heavy and powerful machines to extensive runs of land. The release of dormant fertility thus brought about with the many other changes in the method of the modern planter, has resulted in greatly increased yields of cane and of sugar, in older cane lands. The systems of what may be termed "land management," which have developed concurrently with those transformations have enabled what were formerly regarded as marginal and in many cases quite unsuitable lands to be brought under cane cultivation with highly satisfactory results. In some instances the more energetic and deeper cultivation made possible by tractor-drawn implements, combined with attention to drainage and correct manuring with the standard artificial fertilizers have been responsible, while in others the application of small doses of metal salts has been accountable. The former applies to certain soils of mineral origin in which successive planting cycles have given increasing yields, and the latter to organic soils in which the cane failed to ripen.

52

SUGAR-CANE SOILS 53

Principal Soil Types The cane soils of the world have been divided into six main

types, to which should be added a seventh—highly organic soils reclaimed from swamps.

1. Red lands, occurring extensively throughout the tropics. Iron compounds cause their colour. Though they become sticky and plastic when wet, unlike clays they remain porous. Fertility is at first high, but declines with cropping, and heavy manuring becomes necessary. Lime and organic matter are low and must be supplied by suitable dressings, or in the latter case by cover crops which are ploughed in.

2. Black lands having a clay subsoil, formed sometimes from the sea bed by silting, are rich, but not easy to drain. They are clay loams with an impervious subsoil, and are often shallow and difficult to manage.

3. Black lands with calcareous subsoil, consisting of a light coloured rather soft marl, have a topsoil of loam or clay loam more easily worked than (2) and are highly productive when of sufficient depth. Extensive areas occur in Cuba.

4. Brown clay loams usually derived from shale, have a stiff topsoil which is very difficult to work, but which responds to artificial and organic manures.

5. Alluvial lands, deposited by streams, are of variable composition. They are loams of high and enduring fertility, and easy to work.

6. Sandy loams need liberal applications of fertilizers to enable them to support good crops, but are free draining and easily worked.

7. Soils of organic origin, such as the muck soils of the Florida Everglades formed by rotting vegetation and water-borne silt, which are in effect reclaimed marshland.

The Soil Regarded as a Living Material Within this comparatively simple classification, there are varia

tions of each type. Few sugar-cane lands display any notable degree of uniformity, and many soil types may occur on a plantation of quite moderate size, with marked changes from field to


field. The planter is then faced with the necessity to vary his practice to suit the range of soil conditions he has to encounter. The need for carefully conducted soil investigation has been recognized to an ever-increasing extent during the past 100 years, and research has become intensified on such matters within the past 25 years. The knowledge thus gained is put to practical use through the activities of the various organizations set up to advise and help the planter so that to-day he can readily obtain all information necessary to enable him to use his land to the best advantage. The developments thus possible add to those derived from practical experience, and accelerate progress in correct methods of land utilization. The soil is now regarded more as living material than as dead inert matter. It forms a medium for varied teeming life in the form of minute organisms and larger creatures, which exercise their effect for good or ill upon the material of the soil and the plants growing in it. One of the objects of cultivation is to improve the texture of the soil so as to favour the presence of beneficial life in the soil and to suppress that which may be harmful, bringing about a tilth at the same time that will improve aeration and soil moisture conditions. In this way the plants growing in the soil are provided with an environment favourable to their root development and to the uptake of nutrients essential to proper growth and development. It must also be realized that the soil is not static, but dynamic—or in other words, it is in a state of constant change. Changes occur under the influence of natural forces, such as temperature variations, water and air movement under and on the surface, the growth and decay of plant material. The effects of cultivation are changes artificially induced to assist plant growth, but they must be carefully controlled so as not to interfere with the basic structure of the soil in such a manner as to render it unsuitable for the plants it should support. For these and other reasons land management systems must be related to soil types as well as to crops. In the particular case of sugar-cane which has proved its ability under proper conditions to maintain and even to improve the fertility of the land in which it grows, it is especially important that all operations on the soil should be conducted with these considerations in mind.

SUGAR-CANE SOILS 55

Origin and Translocation of Soils The principal constituent of all soils, with the exception of

those of mainly organic origin is mineral matter derived from the rocks from which they have been formed by natural agencies. Soil formation from parent rock is an exceedingly slow process which is brought about by the influences of temperature changes, water, air, wind and plant growth. Many soils are carried by water, and even by wind to places far distant from their origin, and all when once produced continue to be affected by all those forces which created them, as well as by the living organisms which find in them a suitable and congenial medium for their growth and development. Thus a residual soil may by erosion become transported by water to form an alluvial soil in a river delta, and both by careless and improper cultivation can be exposed to the same danger and carried by drains, floods, and streams to the sea, thus becoming irretrievably lost. These two facts, the slowness of the soil formation process, and the speed with which nature takes revenge for its maltreatment, must constantly control and guide the planter in the use of his basic material—the medium in which plants grow and thrive. This medium is responsive to proper care and attention as well as to neglect and abuse. Success depends upon practices which are soundly based on the former. The planter therefore must have knowledge of the soils which come under his care and usage. Information about their origin, characteristics and behaviour may be obtained from the Government and other institutions concerned with the study of local soils, and methods of land management should be founded on that knowledge, combined with practical experience. For the reasons already adduced, it is clear that there is little room for trial and error in extensive land operations if disaster is to be avoided, and that careful small scale investigations are essential before proved methods are changed.

The Function of the Soil The soil acts as the support for the plant which grows in it, and

supplies that plant with food and water through the root system. The foods or nutrients are dissolved in the water which thus forms the medium by which the plant can obtain its needs. Some


oxygen and carbon-dioxide, and indeed air, must not only surround the part of the plant above ground level, but must also be available in the active layers of the soil itself, the upper portions in which the roots of the plant are growing. Soils then are complex mineral accretions which are composed of the same constituents as the parent rocks from which they are derived, though not necessarily in the same proportions, because the rate of breakdown of the different substances varies widely. Exceptions to this are the organic soils which have originated from rotted vegetable matter mixed with silt brought down by the streams feeding the swamps and marshes in which they were formed. The mineral content of such soils comes from that silt and from the mineral residues of the decayed vegetation, and as will be seen they often lack certain important elements which are essential to plants.

The Elements Necessary for Plant Growth The plant nutrients which are vital comprise nitrogen, potas

sium, sulphur, calcium, iron and magnesium. Of these seven, five are derived from the mineral portions of the soil, and nitrogen and sulphur from decaying plants and organic matter, though some sulphur may be supplied from compounds in the soil. The proportions in which they are made available to and are used up by the plant differ greatly. Calcium, iron and magnesium are normally supplied in assimilable form by the gradual soil transformations which occur at a rate which is sufficient to provide supplies for the needs of the plant. In some soils applications of calcium in the form of lime or limestone are made as correctives. Phosphorus and potassium are often used up at a higher rate than the soil can generate the necessary amounts from the minerals present and they with nitrogen represent the three elements which are conveniently added in various ways as manures or fertilizers to make up the supplies of nutrients required by the plant.

In addition to the seven essential plant foods there are supplementary elements which play a highly important part in plant growth. The presence or absence of minute quantities of them profoundly affects the health and vigour of plants. The more important are boron, copper, manganese and zinc. Traces of still other elements also influence these matters. Certain elements exercise a poisonous effect on plants when present in excessive

SUGAR-CANE SOILS 57

quantities. The position may be depicted in a summarized form:—

Elements Essential to Plant Growth

Carbon (C) Derived from decaying organic matter, and is taken in from the atmosphere.

Hydrogen (H) Oxygen (O) } Supplied by water. Nitrogen (N) From decaying organic matter. Certain

plants can " f i x " nitrogen from the atmosphere and make it available as a plant food.

Sulphur (S) From decaying organic matter, and from the mineral matter in the soil.

Phosphorus (P) Potassium (K) Calcium (Ca) } From decomposed rocks. Magnesium (Mg) Iron (Fe)

Elements Beneficial to Plants Boron (B) From decomposed rocks, or by soil dress¬ Zinc (Zn) ings in correct quantities. Mineral soils Manganese (Mn) } usually contain adequate amounts. They are Copper (Cu) micro-nutrients. If present in soil water Molybdenum (Mo) in excess they may become toxic to plants.

Other Elements These are present in major quantities and their compounds make up the bulk of the soil material in clayey soils.

Sodium (Na) Sodium plays a part in plant growth but Aluminium (Al) } does not appear to be an essential element. Silicon (Si) High concentrations of sodium (and other

alkali) salts cause injury to susceptible plants, while lesser concentrations can retard growth and reduce yield.

Soil Regeneration Soils contain varying quantities of organic matter ranging from

small amounts in sandy soils to 60% or more in " m u c k " and peat lands. The action of soil micro-organisms on plant and animal

5 8 AGRICULTURE OF THE SUGAR-CANE

residues liberates plant foods which form the part of the soil known as humus. This is the principal source of nitrogen for the growing plants in the soil, and the extent to which it is present largely determines fertility. Under natural undisturbed conditions the processes of growth and decay build up the soil reserves, and the fertility of the land increases. The growth and removal of economic crops depletes the available supplies of nutrients in the soil, which therefore must be constantly replenished if the fertility or productiveness of the land is to be maintained. This replenishment takes place in two ways:—the natural breakdown of soil minerals releasing compounds of the elements essential to plant growth at a sufficient rate, and the addition in the form of manures or fertilizers of those elements which are not adequately supplied in that way. The resting of lands by the system called fallowing allows the soil to regenerate itself to an extent which depends upon the time during which it is left undisturbed. A modification of this is green manuring, which is essentially a combination of the two methods. It is effected by growing a cover crop which is capable of bringing about the transformation of nitrogen from the air into a nitrogenous food available to plants. The agencies effecting this are soil bacteria, which obtain their carbohydrate foods from the plants through their roots on which they live in nodules. In the process they " f i x " the nitrogen from the air in the soil in a form in which the plants can assimilate it. These plants known as legumes are members of the pea and bean family. They provide cover to the ground and are capable of supplying up to 200 lb. per acre of combined nitrogen to the soil when ploughed in at the correct time, usually just before they commence to flower. They not only renew the supply of nitrogen available to the sugar-cane, but improve the condition of the soil generally, and in particular increase its moisture retaining capacity.

What the Planter Should Know Though it is helpful to the planter to have knowledge of the

origin and composition of the soil which forms the land in which his crops are grown, it is of more vital interest to him to know its basic characteristics in regard to cultural methods, fertilizer responses, crop production, level of fertility and how that can be maintained or improved, and in general the best system of hus¬

SUGAR-CANE SOILS 59

bandry suited to it. In other words he is more concerned with what he should do to get the best out of it while keeping it in condition for the future than in the fundamental reasons for its presence, derivation and make-up. While, therefore, the importance of soil survey work cannot be exaggerated, the planter's requirements depend upon the application of such information to his own practical needs, which are first the broad cultural operations best suited to the crops he is growing, and the assistance he can given by way of fertilizer dressings, water application if rainfall is deficient, drainage, and treatment directed to the maintenance and improvement of its fertility. In these matters he is guided by experience and the knowledge gained from scientific research conducted on subjects of basic importance and subsequently applied to the problems of crop production.

Soil Grouping in Relation to Cultural Requirements Special interest attaches to a system which has been developed

from investigation and experience by which soils are classified in accordance with their cultural requirements, drainage being included as a cultivation operation. This practical grouping has proved its utility in many parts of the West Indies. Developed by P. E. Turner, it has brought about a reduction and simplification of agricultural methods, has applied mechanical cultivation to better advantage, and has proved its value under a wide range of conditions. While it presents several new features, it incorporates a great deal of established practice in systematized form, indicting where mechanical effort can be economized or applied to better advantage, and providing a planter's guide to soil treatment in a readily understandable form. By this system soils are divided into groups according to the methods of agriculture best suited to them, and subdivisions of a main group are described when differences of main soil type require modifications in cultural practice.

Four Main Soil Groups Turner classifies soils in the following manner:—

Group I.—Soils having a permanent natural tilth, with free natural drainage. They need no ploughing or deep cultivation before replanting, nor do they require drains within the fields.

6o AGRICULTURE OF THE SUGAR-CANE

Examples:—loose alluvial soils; sands and sandy loams in areas adjacent to river beds. Wind-blown sands overlying free draining subsoil.

Group II.—Soils which slowly lose their tilth during the crop cycle. They require to be ploughed or knifed before replanting. Drains are needed within the fields to remove surplus water and to help in maintaining tilth.

Examples:—sandy loams, overlying consolidated and compact subsoil through which water passes slowly, so that a "perched" water-table exists in wet weather or under excess of irrigation water.

Group III.—Soils which should not be ploughed or knifed, but which need drains within the fields.

Examples:—sandy soils and sandy loams in the flood plains of rivers, or having a high water table.

Special cases of Groups II and IV fall into this group, where a shallow topsoil overlies rock, marl or a toxic subsoil.

Group IV.—Soils of poor natural tilth which require ploughing and deep cultivation, and need an elaborate drainage system within the fields.

Examples:—heavy loams and clay soils overlying an impervious clay subsoil, or having a high water table.

Soils in this group absorb large amounts of water which moves downwards through the layer in good tilth and rests on the impervious layer below forming a "perched" or raised water table. If that water table persists the soil loses the tilth imparted to it by the cultivation operations, through successive layers up to the soil surface, so that the effect of the cultivation is progressively destroyed in an upward direction from the level of the lowest cultivated layer. The object of a close field drainage system is to remove this surplus water as quickly as possible. The drains must be below the lowest level of cultivation to prevent the formation of a perched water table in the cultivated layer and preserve the tilth. The cambered bed, and the bed and furrow systems are designed to assist drainage and to maintain tilth in the cultivated layers.

Subdivisions of the four main groups occur, the more im¬

SUGAR-CANE SOILS 61

portant being related to the configuration of the land. The cultivation and drainage requirements are unchanged, but the methods of working differ. The groups therefore are divided into (a) soils of flat areas, and (b) undulating land. Further variations within the groups are brought about by differences in the subsoil. For example, soils of Group I may have subsoils of Group II or IV types and similarly with other groups. The basic principles of the system remain unaltered, each soil being treated in accordance with its characteristics.

The classification of soils in relation to their cultivation requirements in this manner brings to light a considerable amount of unnecessary work formerly carried out on soils of all types, and particularly the heavy intractable clays of Group IV, which was expensive and often did more harm than good, particularly when drainage was not maintained during the operations of deep ploughing and subsoiling, a point discussed on p. 60. The rapid development of mechanization tended in many cases to bring about a uniform method of cultivation for all types of soil. This was followed by a stage where certain modifications were introduced in an attempt to relate the nature and sequence of operations to the type of soil, but much unnecessary as well as unsuitable work continued to be done. What is now classed as a Group I I I soil, for example, was deep ploughed, knifed and drained. Infertile subsoil was brought to the surface, and fertile subsoil turned into the lower layers. The water retaining capacity, already low, was further reduced and the cane barely survived. The area produced an unsatisfactory plant crop and was then thrown out for reconditioning, which fortunately was effected by the use of farmyard manure and factory residues.

This generalized system of cultivation was subsequently modified still further to meet the particular needs of the various types of soil. Turner's classification brings the matter into a convenient condensed form which provides a guide to the planter to be used intelligently and with discretion. It is not intended to be didactic. Groups merge into one another in some instances, and in such cases the system gives suggested methods of soil treatment on which the planter can base his cultivation operations.

The varied nature of the sugar-cane soils of the world is matched by differences in cultural treatment and by the methods and


tools used to impart it. It is clear that these must be co-ordinated, and implements and machines used which are suited to the effort required to perform the work as well as to the rate at which it should be conducted. The light free draining soils can be worked quite soon after rain has fallen or irrigation water has been applied, but they quickly dry out, and though the cane develops a g o o d fibrous root system, it may suffer in dry periods unless covered by a surface mulch of trash or grass. Heavy soils can only be sat isfactorily ploughed and knifed in dry weather, when the soil itself is in a condition to receive a tilth which will persist. Movement of men, animals and machines over the former do little or no damage, while the latter become easily compacted and may lose part or all the effect of the cultivation given to them unless t h e y are properly drained, and movement over them is restricted after the completion of the preparatory operations for planting.

Research has disclosed that special measures have to be adopted to enable some soils to respond to cultivation, to induce the cane to mature, and to restore fertility and structure after the com¬ pletion of a plant-ratoon cropping cycle. Reference is made to standard practices of fallowing on p. 148, but particular interest attaches to the muck soils of Florida, and the cane lands of British Guiana.

T h e Peat Soils of Florida

The reclamation and controlled drainage of the organic soils in the Everglades of Florida made it possible to commence t h e growing of sugar-cane in 1923. Nothing was known about t h e behaviour or treatment of the land for successful crop production and difficulty was experienced in getting cane to grow satisfactorily. The application of dressings of copper sulphate at the rate of 20 lb. per acre was suggested by Dr. B. A. Bourne based on physiological plant responses observed on raw peat soils in t h e State of New York by E. L. Felix. This treatment brought a spectacular stimulation of growth and rapidly led to the expansion of the industry. Although vegetative growth became highly satisfactory, delayed maturity of the varieties grown occurred, and the breeding of new varieties was commenced in 1926 with t h e object of evolving canes which would mature early and withstand the cool weather and frosts which occur in the winter season. T h e

SUGAR-CANE SOILS 63

work was markedly successful, but delayed maturity was still experienced. Bourne having noted the increased growth of cane brought about by zinc sulphate recorded by other workers, studied the reaction of cane to this chemical used in association with copper and manganese, and found that the ripening of the cane was improved and advanced. This work has been continued, and the application of soil amendments or improvers (as distinct from manures or fertilizers) has for many years been standard practice. The sulphates of copper, manganese and zinc are used at rates related to the requirements of the land. A standard dressing for low-mineral organic peat soil is 67 lb. manganese sulphate (60%) ; and 25 lb. each of commercial copper sulphate and zinc sulphate (89%) per acre at the time of planting.

Br i t i sh G u i a n a

The heavy frontland clay soils of British Guiana were found difficult to regenerate after the completion of the plant-ratoon crop cycle until the method known as "flood fallowing" was evolved. These soils crack and dry out rapidly on the surface during dry weather and require flood irrigation at such times despite the comparatively high average annual rainfall of 80 in. in the east (Berbice) and 92 in. in the west (Demerara). This treatment corrects the physiological drought caused by the high salt content of the soil which would otherwise occur, as the excess of salt is removed by solution in the water which is subsequently pumped off into the drainage system. The tilth of the land is completely lost in the cropping cycle and is restored by drowning the land—submerging it under fresh water to a depth of about a foot above the highest parts for at least six months. During this time aquatic weeds grow in profusion while land weeds are destroyed and the old cane stumps and roots rotted. The texture of the soil is improved, and its fertility increased. The addition of molasses to the water at the rate of 5 tons per acre has been found to be advantageous. At the end of the fallowing period the water is pumped off. The water weeds remain on the land and are ploughed in when the first operation of preparation for replanting takes place, as soon as the land is dry enough.

The ability of a soil, which is otherwise suitable for the growth and maturing of sugar-cane to produce satisfactory crops, depends


on its physical condition, moisture relationships, and the availability of adequate amounts of plant nutrients. Within limits all these can be influenced by cultural practices, and the objects of cultivation, drainage, irrigation in the absence of sufficient and well distributed rainfall, manuring and soil improvers, are to achieve and maintain for as long as may be desirable, the combination of all these factors most suited to optimum yields.

Physical Condition The operations of ploughing, knifing and harrowing are intended

to loosen the soil and separate the particles without destroying its structure, in order that air and moisture may freely penetrate to the full cultivation depth and to assure the most favourable conditions for root development. After ploughing it is usually necessary to leave the land for a time to weather and become drier in the surface layers so that the deeper cultivation of knifing or sub¬ soiling (when that is necessary) can be fully effective, and the clods or lumps crumble. Harrowing speeds up this break-up of the clods when ploughed land has been left to the action of wind and sun for a few days. In this way the " t i l t h " of the soil is brought about where it does not exist naturally. The permanence of this induced physical condition or tilth depends upon the inherent characteristics of the soil itself, its water relationships, and artificial changes brought about by the treatment to which it is subjected, some of which have already been discussed. The length of time during which the soil retains the tilth mechanically imparted to it —whether by manual, animal, or power-operated tools—determines very largely the number of successive crops of cane which can be grown in it from one planting. Different varieties of cane vary in their "ratooning" power ; that is, in their ability to continue growing and yielding good crops from a single planting. Soils also naturally differ in "ratooning power," and may be assisted to possess this in a higher degree by proper systems of soil treatment and crop husbandry.

Moisture Relationships The tilth of the soil influences its capacity to retain moisture,

which dissolves the plant nutrients ; to release the solution thus formed to the roots of the cane ; and to dispose of the surplus

SUGAR-CANE SOILS 65

through the pores and interstices between the soil particles to the drains. The extent to which natural drainage must be supplemented varies widely, not only with soil and subsoil types, but with natural slope of the land, and the wide range of rainfall in total amount and rate of precipitation. The discussion of the group system indicates the essential role played by drainage in the maintenance of tilth under conditions which favour the use of the cambered bed system of field arrangement in its various forms. Artificial watering by surface or overhead irrigation is of no value unless the soil is in suitable physical condition to receive, use and release the applied water. Irrigation may destroy tilth in soils which are easily compacted, those which form crusts under the influence of water, and in the heavy clays, unless the greatest care is taken in distributing the water, and surface cultivation given as soon afterwards as possible. Drainage and irrigation are more fully discussed in other chapters, but reference to them must also be included in a consideration of sugar-cane soils.

Plant Nutrients Distinct from physical soil conditions, though related to them

are the chemical and biological factors which provide the material upon which the plant feeds. Soils differ in the amount and availability of plant foods which are naturally associated with them, as well as in the rates at which new supplies are released from the reserves in the soil itself. Again the physical condition, the tilth of the soil, exercises its influence. Soils in good tilth have their soluble nutrients readily accessible to the plant, whether they are derived directly from the soil itself, or have been added in the form of artificial dressings. However rich and fertile a soil may be, and however well supplied with improvers and manures, the plant cannot develop an adequate root system to take up the nutrients required for growth in the absence of good tilth.

CHAPTER 5

THE DRAINING OF SUGAR-CANE LANDS

Reasons for Drainage The successful cultivation of economic crops largely depends

upon adequate drainage of the land in which they are grown, and sugar-cane is no exception. Drainage may be defined as the means by which soil and subsoil water is controlled and removed in relation to the health and vigour of the crop. The water on, in, and under the soil may be naturally present as a result of various conditions. Underground streams, springs, water drained from higher land, impermeable subsoil, inadequate runoff, a high water table, heavy falls of rain in short periods can individually and collectively give rise to the need to assist natural drainage by carefully planned artificial means. Irrigation may be a danger, particularly if heavy applications of water are made, in the absence of satisfactory drainage. Different plants vary remarkably in their reactions to water in the soil. Coconuts, for example, thrive and yield heavily with tiny trickles of constantly moving fresh water near the surface of the land in which they stand. Under similar conditions sugar-cane may grow luxuriantly but it will not mature. Stagnant soil water is fatal, and land that is constantly too wet positively harmful. The cane needs warmth and air underground as well as above ground. Water-logged land is cold and airless, and whatever the apparent fertility status of the soil may be, it will not grow profitable crops unless these adverse conditions are corrected. Sugar-cane requires large supplies of water to support its growth, but like most other crops cannot tolerate wet feet Thus while ample water is needed a well-drained soil is essential.

A Simple Method of Soil Examination Whenever cane shows signs of distress, abnormality, delay or

failure to mature, and low sucrose content at the normal season for ripening, it is wise to examine the roots and the soil. A useful instrument for the latter purpose is an ordinary 1 1/2-in. auger with the bit point cut off, having a total shaft length of 3 ft. 6 in. with

66

THE DRAINING OF SUGAR-CANE LANDS 67

a crosspiece at the top which may be removable. The bit and shaft should be marked at 6-in. intervals from the bottom so that successive bores can be made to a total depth of 2 ft. or more. Visual and touch tests of the soil are made by boring the first 6 in. and pulling out the bit without rotating it. Except in dry sandy soil earth will be held in the spiral of the bit from whence it may be removed, inspected and fingered. The bit is then cleaned and further 6-in. cuts similarly made and examined from the same hole. Care is necessary not to jerk out the auger, but to withdraw it slowly with a firm upward pull. Under most conditions this simple method will disclose the depth of the surface soil and its condition, the nature of the subsoil, the presence of hard or soft rock near the surface, the moisture gradient from the surface downwards, and excessively wet soil or subsoil within the main root zone of the cane. Such tests should be made at various points in the fields at convenient intervals of time during the wet and dry seasons, and at different stages of the crop cycle. After some experience the observer will be able to relate the soil conditions thus noted to the general appearance and requirements of the cane so far as its moisture relationships are concerned. Where irrigation is practised the observations will assist in determining when to make the next application of water.

Field Drainage Systems Field drainage systems for sugar-cane are of several types, and

it may sometimes be found desirable to use more than one of them on the same plantation. Although it is usually flat land that may need assisted drainage, sloping land is not always sufficiently freed naturally from surface water. The basic principles of field drainage are to assist land to get rid of such surface water in the upper layers of the soil in a manner that will maintain conditions which provide for aeration, warmth and adequate moisture within the root zone of the crop. Methods of field drainage comprise under-drainage and surface systems. Underground drainage includes mole, tile and stone drains constructed according to pre-arranged plans and designed to serve for as long a time as possible.

Mole Drains Mole drains are circular in cross-section cut in the soil at a

pre-arranged depth by means of a cylindrical torpedo-shaped tool


mounted at the bottom of a blade fixed to a carriage which can be drawn over the surface of the land in such a manner that the mole is pulled at the required depth through the soil. Cable tackle, tractors, and very occasionally animals, are used to provide the necessary power. The essential part of the equipment is the mole itself. Various simple modifications of the basic design are used. The rearmost portion is slightly bigger than the main body so as to expand the hole slightly and leave it with as smooth a surface as possible. The type of mole should be suited to the soil in which it is to work. This method can be used with advantage where the soil texture is such that the drain will not easily collapse. A high proportion of clay in the subsoil is a desirable feature. In favourable circumstances mole drains will give efficient service during the complete plant-ratoon crop cycle, and in some cases they have continued to do so over many years.

Mole drains are usually 4 or 6 in. in diameter. An important part of the drain is the cut made by the blade to which the moling tool is attached. This cut assists the passage of water from the surface and through the soil to the drain itself and improves aeration. Mole drains have been successfully used in cane lands in Fiji, where the original cuts were made by steam plough cable tackle. In the Florida Everglades, the United States Sugar Corporation use mole draining as standard field practice (Fig. 12), Mole drains require not only suitable land, but proper grading of the drains and free outlets at the lower ends.

Tile and Stone Drains Both tile and stone drains are laid in deep trenches cut at pre

determined intervals to a depth of 30 in. or more with a slight fall towards the outfall end. It is important that these, like mole drains, should be cut well below the level at which the deepest cultivation implement will work. They usually possess a much longer useful life than mole drains and are more expensive to construct. Both of them require deep trenches, which may be cut by mechanical means. The tile drains are formed by hollow cylindrical clay tiles 4 or 6 in. internal diameter, which are laid end to end regularly at the bottom of the trench without any joining. They are covered with a layer of trash, brushwood or similar material and the trench is then filled in with earth. Con¬


crete can be used in place of clay. The successful operation of this type of drain depends upon the movement of water through the soil towards the drain, and the presence of small unobstructed spaces between the hollow tiles which are so laid as to form a continuous channel with a uniform gradient leading to a free outfall.

The stone drain is similarly made, packing the bottom of the trench with stones which will pass through a 4-in. ring.

With both types it may be desirable in some cases to raise the surface of the land slightly between the drains leaving a small depression over them in order to assist the movement of surface water towards the drain. The useful life of such drains should exceed 20 years. The distances between them depend upon the nature of the soil, rainfall conditions, and slope of the land.

Short lengths of bamboo with the septa punched out have been successfully used in the place of clay tiles or stones, but the life of such drains is comparatively short as the material rots quickly and collapses. Treatment with tar or cement slurry will give longer service. The latter method with several dippings into a mixture of cement and water with intervals between each should result in a desirable "tile." Two or three channels are laid at the bottom of the trench and covered and closed in as described.

Precautions It is important that underground drains should be entirely un

disturbed by the passage of implements and tractors. "With mole drains, renewed each time the land is replanted, the normal operations of inter-row cultivation, reaping and transport, and treatment of ratoon crops will not be seriously harmful so long as they are carried out when the land surface is reasonably dry. The cut over the mole may be affected but will still function unless the soil is disturbed when wet when it may become partially closed. It is, however, found in practice that the cut displays a remarkable persistence under all normal land working conditions except heavy ploughing and subsoiling.

Advantages of Under-Drainage The advantages of underground drains are the low maintenance

costs and the unobstructed passage of haulage systems and


implements over them. Arable land is not sacrificed as is o f t en the case with surface drainage of fields. While mole drains c a n only be used in subsoil in which the channel and cut above it w i l l not seriously collapse during the life of the crop, tile drains a n d their substitutes, the stone and bamboo types, can be put down in any cane soil through which water can pass freely from the surface, including all but very heavy clays. The distance between drains may range from 30 to 240 ft. depending upon the nature of the soil, the rainfall and the depth at which the drains are la id , with even closer spacing in the heavier soils. Regular attention to outfalls is necessary so that water coming from the field drains may pass freely away. The water level in outfall drains should be lower than the discharge from the field drains, except perhaps for short periods during exceptionally wet weather.

Under-drainage, particularly mole and tile drains, is especially suited for irrigated lands having free draining soils, and satisfactory outfalls for the field drains. Apart from their main function, the control and relief of soil water, they can be u s e d as indicators for control of water application, and as part of a collecting system for relifting water. Few, if any, irrigated lands n e e d no drainage, and often the land and the crop suffer from the effects of inadequate drainage. Surface drains are troublesome to maintain, and water distribution interferes with them, the converse being also true. There is therefore often a tendency to neglect drainage in an irrigated plantation. In some cases at tempts are made to use the furrows and head ditches in the dual capaci ty of drains and water distribution channels, with deplorable r e su l t s .

Under-drainage assists in protecting the soil from erosion, and the finer particles of surface soil carried away in large quantit ies by field trenches used with the bed systems now to be described are retained. The drainage water discharged at the outfalls w i l l be found almost invariably clear, in great contrast to the discoloured silt-laden water from open field drains. Though some of t h e soil thus washed off the bed surfaces is deposited in the trenches and head-drains, being returned to the land when they are c leaned and reformed, the damage to the soil may be serious when it is left unprotected by vegetative growth. Even then large quanti t ies of fine soil particles are carried from the fields and irretrievably lost.

F I G . 10.—Arrowing (flowering).

[Courtesy of Tate & Lyle Ltd.

FIG. 11.—Drainage ditch, Florida Everglades.

[Photos by courtesy of U.S.A. Sugar Corporation

FIG. 12.—A moling plough, Florida Everglades.


Open Trench Systems A widespread practice in non-irrigated land, particularly in the

West Indies, is the combined bed planting and drainage system with surface field drains or trenches leading to head drains discharging to the main drainage channels, which may be natural water courses or artificial cuts. The object of the method is to relieve the upper layers of the soil from surplus water as quickly as possible after heavy rain, and to pass it to the main drains as quickly as conditions permit, and with the minimum risk of erosion or damage to the cane. The field trenches act in the combined role of temporary reservoirs and drains. They are cut at intervals of 22 ft. or more from centre to centre on a slight incline towards the head drain which conveys the water to the main channel. The earth between the beds is higher in the middle than at the drain edges, being built up by the soil excavated from the trenches and the bed edges. The drains are approximately 18 in. wide and of the same depth, tapering to 12 or 15 in. at the bottom. When 22-ft. beds are used the cane is normally planted in rows 4 ft. 6 in. apart, the old practice being to plant across the bed. Mechanized field work has brought about planting parallel to the drains, the space between the outside rows—those nearest to the drain edges —being usually greater than that between the rows on the bed. There is thus a considerable sacrifice of land for the drains, which under the conditions described extend to a total length of 2,046 ft. per acre, and occupy 7% of the total area. In some places the beds are 24 ft. from drain centre to drain centre, and cane rows 6 ft. apart, when there is no loss of plantable land, though nearly 1,850 linear ft. of field trenches per acre have to be cut and maintained, equivalent to excavating 3,500 cu. ft. of soil per acre. The capacity of the field trenches filled to the drain edges in the 22-ft. bed system just exceeds 1 in. of rainfall. The rate of run-off depends upon the gradient and the discharge capacity of the main drains which is usually very low during the rainy season. Rainfall intensity often approaches 1 in. per hr. with precipitation of 3 in. in 24 hrs. Occasionally these figures are exceeded. The soil becomes saturated with water and flooding in low-lying areas may occur through failure of main drains to convey water quickly enough. Though these conditions rarely persist for more than two or three days at a time they can cause serious damage to the crop.


The bed system thus described is cheaper in first cost than tile or stone drains, but has to be partially re-formed when land is prepared for replanting as ploughing operations however carefully carried out do some damage to drains and beds. Once drains are cut and beds formed, subsequent operations during the crop cycle have to be conducted so as to cause the minimum damage to the drains. They have to be cleaned and maintained in working order, work which is still extensively done by hand, though mechanical methods are coming into increasing use. Any lack of attention is speedily accompanied by damage to the crop in wet weather. This and other forms of surface drainage represent a heavy item in the total cost of the crop. The choice between surface trenches and tile or stone drains, assuming conditions are favourable to the latter, is one between a high initial capital outlay with long life and negligible maintenance charges on the one hand, and low establishment cost with continuous and expensive maintenance oa the other.

Condit ions W h i c h Suit C a m b e r e d B e d s In general the cambered bed system of drainage and cultivation

is suited to large flat areas with heavy soils and very small natural slope, where rainfall is high in total amount and intensity of precipitation. The older system of planting across the bed, using manual labour for cultivation, increased the rate of run-off to the drain, but encouraged surface erosion which in some conditions was noticeably serious. Cane rows parallel to the drains bring about a relatively slower movement of water across and under the surface of the bed. If this impedance becomes excessive the cane rows can be interrupted every chain or so to allow water to pass more freely. Mechanized field work can be performed with rows planted along the bed, but not with the transverse method of planting, though certain operations are difficult if damage to the drains is to be avoided. Cambered beds are unsuitable for light free draining soils, for irrigated land, and for sloping land with a gradient exceeding about 1 in 15. Field drains should be cut at a very slight angle to the contour even in gently sloping land, and the lines of head drains must be carefully chosen to avoid erosion and damage.


Cambered Beds in British Guiana The cambered bed system as used in British Guiana where the

sugar lands are below sea level represents a special case involving the removal of surplus precipitation from the beds, and their relief from irrigation water after fields have been flooded in dry periods. A general description of the drainage of these lands is given later, but reference to the practice in regard to the beds is made at this point. The fields are subdivided into beds 35 ft. wide by trenches about 2 ft. in width and depth, which discharge to a drainage canal. In the "English bed" method most generally used, these ditches run parallel to the longer sides of the field, and in the " Dutch bed " system, across the field. The cane is planted in single or double rows transversely. The effectiveness of the field drainage is dependent upon the maintenance and proper operation of the main drainage of which a vital part is the removal of immense volumes of water by pumping.

The Bank and Furrow Method The planting of cane on single banks with deep furrows between

them has been developed in Louisiana for low-lying almost level land with a high water table and heavy rainfall. The soil is alluvium with a light loam over most of the cane lands, there being some areas of medium clay. The subsoil is impervious and the land difficult to drain by other means. The basic principle is the formation of banks of soil on 6-ft. centres with furrows between them which act as drains. The cane is planted on the top of the banks, each row thus having a field drain on both sides. The banks and furrows are mechanically formed by specially designed implements attached to the hydraulically operated tool bar of a rubber-tyred high clearance tractor. The tops of the banks are kept 18 in. or more above the furrow bottoms, and most operations along the banks or ridges are mechanically performed. Sixteen to twenty-four banks form what is called a "cut," which is a rectangular block or field bounded at each end by field intervals. Field ditches 4 to 6 ft. wide, and of varying depths governed by the gradient, separate the cuts, and run parallel to the ridges. Water reaches the field ditches from the furrows by cross drains cut a little deeper than the furrows, and graded from the middle of the cut to the ditch. These cross drains or "quarter drains" are spaced one chain or


more apart according to the type of soil, being closest in heavy land, and may originally be formed by a mule-drawn furrower, though they have to be maintained by hand. It is essential to put them in immediately the beds have been formed, to avoid damage to soil tilth by heavy rain. They are disturbed and filled in by each tractor cultivation of the beds, and have to be re-formed manual ly. To permit the use of the intervals for headland turns, t h e cross drains are not cut at the ends of the fields, but a few y a r d s away. The field ditches lead into permanent canals, controlled by district drainage authorities, which drain into bayous or swamps.

Merits of the Bank and Furrow System This single bank and furrow system has been successfully

adopted in other countries where similar conditions prevail. Disadvantages are the "quarter drains" and the effect of trash when the cane is not burned before reaping. The quarter drains involve high maintenance costs which to some extent counteract the comparatively inexpensive system of mechanical cultivation associated with the method. The possibility of permanent cross drains appears to be ruled out by the passage of tractors a n d implements along the furrows and beds eight times or so d u r i n g each year. The trash may partly fill the furrows and impede the passage of tractors and the work of implements, though this t r oub l e can be minimized or avoided by the use of notched discs for cultivation work. During the early period of growth of the c a n e the banks are weeded, cultivated and their shape maintained by light tractor-drawn implements. The distance of 6 ft. between furrows enables high clearance rubber-tyred tractors to move easily with their wheels in the furrows when land conditions are sui table . Stubble shavers and reforming tools are used after each c r o p has been reaped. When a field is due for replanting, the b a n k s are split, or reversed, and the furrows filled so that new b a n k s are formed over the former furrows. An advantage of the system is the cutting and maintenance of the row drains concurrently w i t h the operations of land preparation and crop cultivation. The m e t h o d is adaptable to a wide range of conditions, but is unsuited to s teeply sloping land. Its chief merit is in its application to areas w h e r e soil water conditions would otherwise render sugar-cane product ion uneconomic or impossible.


Natural Drainage Land with pervious soil and free draining subsoil does not

usually need a closely spaced field drainage system. If levels permit of the steady flow of surplus water through the soil, deep drains at the lower edges of fields which are interconnected with a system falling gently to a main outlet will often be sufficient. It may occasionally be desirable to put in a few widely spaced supplementary surface channels in the field, leading to the head drains, or to tile drains at wide intervals. Naturally free draining soils present no difficulty with irrigation as few or no drains are needed in the fields.

Drainage of the Florida Everglades The sugar-cane lands of Florida form part of the vast area of

muck soil, consisting of more than 60% organic matter, known as the Everglades. The land is practically level, having a fall of only 3 in. per mile. It borders on Lake Okeechobee, an expanse of fresh water 730 sq. miles in extent. This 4 1/2 million acres of organic soil is in effect reclaimed swamp land, which has been made available for agricultural purposes during quite recent years by an extensive and well controlled main drainage system by which the level of the water in the lake and in the whole network of canals and drains is carefully regulated. The general control of the whole drainage system is vested in a statutory authority. The area is divided into sub-drainage districts controlled by local bodies deriving their power from the Authority, and responsible for the construction maintenance and operation of the subsidiary drainage works within their district. The lake is surrounded by large embankments, and its level controlled by the overflow through a number of main arterial canals which discharge into the Atlantic Ocean at different points on the east coast of Southern Florida. The inflow to the lake from the watershed to the north is also regulated, and provision for flood control made for the whole of the drained area. The complete drainage works consisting of locks, dams, levees, pumping stations and lateral canals right through to the mole drains in the cane fields, are tied in with these main canals which control the level of the lake and the water table throughout the area. Capital charges and maintenance costs are borne by the landowners who pay an annual tax on their land.

The sugar lands of the United States Sugar Corporation form a


sub-drainage district controlled by the Corporation itself as the local authority, through a special technical and construction staff. Water control in a sub-drainage district depends upon embankments which are constructed on the boundaries to prevent the ingress of water, and an interior system of main and subsidiary canals with low lift high volume pumps to discharge water from the area, or to bring it in according to requirements. The capacity of the drainage system is designed to provide a run-off adequate for local precipitation, usually 1 in. in 24 hrs. The topography lends itself to a uniform rectangular lay-out of drains and main canals, the latter usually being spaced 2 miles apart with a length of not more than 8 miles. Laterals are on 1/2-mile spacings with a total length of 1 mile. The size of fields is thus conveniently defined, each being 40 acres in extent with field ditches a 1/4 mile apart and 1/4 mile long, forming the boundaries (Fig. 2). The ditches are closed at one end, and each leads into the lateral at the other, being connected to it by a 30-in. culvert which enables the banks of the laterals to be used for farm roads (Fig. 11). The blocked ends provide space for headlands or tracks. The final operations prior to planting comprise a light harrowing and levelling, after which fields are mole drained parallel to the laterals. The tractor-drawn moling tool is 6 in. in diameter, and the drains are cut on 15-ft. centres about 40 in. belowthe surface with outfalls into the field ditches. The cost of moling under these conditions is low, one man with an assistant being able to complete 40 acres in a day.

Pumping for a sub-drainage district is effected by pumps with capacity ranging from 30,000 to 60,000 gal. (Amer.) per min. at a static head of 5 ft., operated by diesel engines of 80 to 180 h.p. Auxiliary pumping is done by portable turbine-type pumps so designed that they are easily installed in the gate guides. They have intake and discharge openings on opposite sides, and by turning, the units can be arranged to discharge in either direction, or to allow gravity flow through the pump. The capacity of each is 6,000 g.p.m. Power is provided by 20 h.p. engines.

Sugar-Cane Lands Below Sea Level The sugar industry of British Guiana is conducted on land

reclaimed from the sea and from swamps some 200 years ago. About three-quarters of the area devoted to the crop consists of

THE DRAINING OF SUGAR-CANE LANDS 77 rich, heavy, acid, marine clays, in which appear strips and masses of sand, the remainder being organic soil of poor water retentive capacity and low fertility. The present sugar plantations with their land devoted to related purposes are 155,000 acres in extent, of which about 60,000 acres are reaped annually. Five rivers traverse the area and discharge into the Atlantic Ocean. Extensive sea walls, maintained by the Government, give protection from the encroachment of the sea, and river embankments kept up by the estates control the rivers. A small portion of the total area can be drained by gravity at low tide, but the remainder is controlled by pumping, usually by equipment mounted on pontoons or barges. The land is sub-divided into long strips having frontages to the sea and running inland for several miles. Behind the cane lands a catchment area for irrigation water is maintained by an independent Conservancy, together with a main irrigation canal running roughly parallel with the coast, from which water is supplied to the plantations. The individual estates are each enclosed by an embankment or empoldering dam. The portion at the seaward end is the " sea dam," those on each side being the " side line dams " and the one at the rear the " back dam." Fields are of 10 to 12 acres in extent, rectangular in shape and surrounded by a polder and canals, each of which is named according to its position. The arrangement of fields is shown in Fig. 13. The canals are of two types, one for irrigation and transport and the other for drainage. The irrigation distribution system is at a higher level than the drainage canals which are larger and deeper. It has been estimated that each square mile of cane land has 49 miles of drainage canals and ditches, and 16 miles of high level waterways used for irrigation and transport. The disposal of the irrigation water and water derived from rainfall, averaging 80 to 91 in. annually in the two main districts, is very costly. Added to this expense is that of the constant maintenance of canals and dams, most of which is still done by manual labour, though mechanical devices are coming into increasing use. Luxuriant growths of weeds which develop rapidly and deposits of mud and debris which would soon choke the canals have to be dealt with. The whole system of sugar-cane cultivation in British Guiana is unique and may well be called an amphibious operation. Reference to others aspects will be found in Chapters 2 and 5.

Fig. 13-Diagram i l luming field layout. The top field is planted in tbe English Navigation and draniage canals are also

[Reproduced from Report of a C o m m . o f Enquiry into

English Bed System, the bottom in the Dutch Bed System. are also shown.

inquiry into the Sugar Industry of British Guiana by permission of the Controller ,H.M. Stationery Office


Local Pump Drainage In low lying almost level land with a very slight fall, h igh volume

low lift centrifugal and impeller pumps are often used to supplement local gravity drainage during periods of high rainfall when the unaided surface run-off is inadequate. The basic equipment required is mechanically simple, and when properly installed needs very little attention. Diesel or electric power can be used, the latter being preferable as it lends itself to automatic operation of the pumps. Similar methods are used to remove t h e water discharged from a mole- or tile-drained area when natural conditions found in low lying lands would otherwise prevent t h e under-drainage system from working properly. The pump discharge can be delivered into a canal raised above ground level, or to a higher point of the land from which it can flow freely away from the drained area. Small portable pumps of high capacity adapted for belt drive from an engine or tractor for temporary emergency drainage at points where this is needed are capable of giving efficient service. Schemes of this type are often used on parts of individual plantations where the whole drainage system is under the owner's control.

Drainage as a Cultivation Operation The construction and maintenance of field drainage works are

essential and important parts of the whole range of cultivation operations in land where natural conditions of soil texture and topography do not allow the speedy and free removal of surplus water from the upper layers of the soil. Drainage must be effective at the proper time, or the success of other work on the land may be put in jeopardy. Mention has been made of the need to cut the quarter drains immediately the beds and furrows have been formed in the Louisiana method. The cambered bed system is just as much dependent upon drains being in constant working order even though they may not be fully formed after damage during ploughing. If the drainage is badly impeded after ploughing and harrowing, the soil may become water-logged and lose its tilth, which it may not be possible to restore for months after. Thus effective drainage must be available to remove excess water throughout the period of preparation and cultivation as well as


during the whole life of the crop. The interior drainage of an estate or plantation is the responsibility of the owner.

Conservancy Authorities Field and farm drainage forms part of the water and soil con

servancy measures which are important to the protection of the land and the welfare of communities. It is rarely possible for a drainage scheme for a plantation to be planned and conducted entirely independently of neighbouring interests, exceptions being small isolated areas with a water course conveniently near which can act as a main drain without interference with conditions lower down the stream; and large areas under single ownership and control where independent and comprehensive drainage works are possible. In a single drainage basin some suitable form of unified and regulated action by all landowners is essential. Examples given are Louisiana, the Florida Everglades and British Guiana, in each of which the safety and success of agricultural operations depend upon the co-ordination of all land drainage in conformity with the requirements of the whole drainage area. The usual system is to appoint conservancy or drainage boards under the provisions of laws enacted for these purposes. Such authorities are given wide statutory powers enabling them to plan, construct, control, and maintain area schemes of main drainage, and to require all landowners within that area to erect and maintain the necessary subsidiary drainage works on their own land.

CHAPTER 6

PESTS AND DISEASES, THEIR EFFECTS AND CONTROL

Early Limitations on Cane Varieties Foremost among the numerous changes and developments

which have occurred during the past 100 years is the result of the discovery that the sugar-cane produces fertile seed. It was long believed that the sugar-cane was incapable of producing fertile seed, although it now seems certain that in the past new varieties have arisen through the accidental germination of cane seed under field conditions. Until the modern techniques of sugar-cane breeding proved their ability to provide new and better varieties of sugar-cane the planter had perforce to confine himself to the limited range of commercial canes available. Even then constant search for improved types was made, and interchange between one country and another went on, both openly and surreptitiously. The causes and methods of control of pests and diseases were little understood and protective quarantine measures did not exist. The risks of introducing pests and diseases with new importations of plants, including sugar-cane, were great, but were gaily undertaken in the course of official missions, the accidents of war, and the activities of private enthusiasts. As with other economic plants the increasingly high populations of sugar-cane grown in closer proximity brought about more favourable conditions for attacks by pests and diseases, to which was added the effect of exposure to introduced enemies which accompanied new plants including the sugar-cane, brought in to the various countries from overseas for the extension and development of agricultural industry. Fortunately the slowness of sea transport prior to steam propulsion and the unfavourable conditions under which the plants were carried enabled only the most healthy and vigorous to survive, but many of the agencies which adversely affect plant life were, however, thus inadvertently distributed.

82

PESTS AND DISEASES, THEIR EFFECTS AND CONTROL 83

Plant Quarantine The recognition of the importance of strict control of plant

importation under specific conditions contained in official permits, and the quarantine of those allowed to come in is a comparatively recent innovation. The more slowly moving sea transport which until very recent times brought about conditions under which visible signs of disease or insect attack could appear, helped the work of those responsible for plant protection to detect readily any undesirable characteristic. Plant importation and quarantine measures have been progressively improved, until now some countries require that new sugar-cane plants imported under carefully specified conditions shall be grown in quarantine for a period of 2 years before being released ; and even then they are handed over to an officially recognized research institution for use either in connection with cane breeding or for field testing in regard to their commercial suitability.

Effect of Air Transport The speed with which modern air transport makes it possible

to convey new plant material from one country to another has removed the time factor of more slowly moving sea transport so that even stricter measures and much greater care are necessary to protect the planter against the risks of introduced pests and diseases. Insects which easily obtain access to passengers' baggage and other goods now have a good chance of survival under air transport conditions, while flowers, fruit and parts of plants picked up by the air passenger and often unintentionally imported are a greater menace than before. Seeds of undesirable plants may become attached to clothing. They collect in such places as trouser cuffs and to mud on shoes. There are now numerous ways in which pests and diseases of plants and undesirable plants can be distributed unintentionally and accidentally. Apart therefore from the protective measures taken at airports, regular and careful inspection of surrounding areas should be carried out. A further protection might be the prohibition of the growing of certain economic plants within specified distances of such places, as a protection against new insects, diseases and weeds becoming established and getting out of control.


The Planters' Interest It is essential that the sugar-cane planter should appreciate

fully the dangers of possible new introductions of enemies of the cane, and should himself support the measures which are taken to protect the industry in which he is so closely interested. Unfortunately this attitude is not always displayed by those who are most vitally concerned. Recent cases of cane smuggling have occurred, the effects of which may not yet be fully evident. Such actions in the past have brought about the introduction of economic pests and diseases which have menaced various crops, including the sugar-cane. The sugar-cane leaf hopper, which transmits the gravely serious Fiji disease, was brought into Hawaii by a consignment of sugar-cane cuttings from Australia. Thus separated from some of its natural enemies it became rapidly established, causing extensive damage to sugar-cane until it was brought under a satisfactory degree of control. It remains a potential danger to the sugar industry there because it would bring about the spread of Fiji disease if that should ever find its way into Hawaii. Fortunately for the Hawaiian industry, the cuttings associated with the introduction of this insect were not affected by that disease. Mosaic disease is stated to have been introduced into Jamaica by infected cuttings smuggled into the island by a planter. That disease has been a constant anxiety to all connected with sugarcane growing for more than 30 years.

Weed Introductions The rapidity with which some plants establish themselves under

new and favourable environmental conditions is remarkable. Darwin in his Voyage of H.M.S. Beagle commented on this fact in connection with the guava in the Galapagos Islands. This plant is a serious problem in pastures and unused land in Fiji. Clidemia hirta, a common but not troublesome weed, in parts of the West Indies, was accidentally introduced into Fiji not many years ago and has latterly taken charge of extensive areas to the almost complete suppression of all other plants in lands cleared for pastures. The so-called " Seymour grass " Andropogon perpusus of Jamaica came to that island as seed in a military officer's baggage and has spread with great rapidity. For many years it was confined to places in and near to the garrison, but internal


road transport has brought about the recent rapid distribution of it to all parts where favourable conditions exist for its growth. These examples in regard to pests and diseases could be multiplied. They are quoted to emphasize the great importance of strict protective measures against new introductions of plant enemies, and the necessity for all members of the public, and in particular the planting community, to appreciate the reasons for them and to co-operate in carrying them out.

PESTS AND DISEASES OF SUGAR-CANE

A Vigilant Outlook The sugar-cane is attacked by an extensive variety of pests and

diseases which affect different parts of the plant and bring about damage and loss ranging from negligible to gravely serious proportions. Each country offers its own peculiar problems of incidence, effect and methods of control of the agencies which bring about these conditions. Constant study by research workers, and vigilance and action on the part of planters are necessary to combat the various enemies of the cane, while protective measures against the introduction of new ones and the spread of those already present are the concern of territorial Governments on the one hand and agricultural industries on the other. Methods of control are generally specific for particular forms of pest or disease within one country, but they are not always of universal application. The study of local problems, while assisted by knowledge of conditions and practice in other countries, must be conducted within the particular ecological area in which they occur. Though pests and diseases differ so remarkably in their effect upon the cane, the view is taken that all should be regarded as potentially dangerous, though comparatively few may be of present economic importance. Each ecological area should possess facilities for the continuing investigation of all creatures and organisms affecting sugar-cane, so that basic knowledge may be accumulated, changes in the extent of damage to the crop observed, and remedial or protective measures taken in good time to prevent the pest or disease from becoming a major danger. The importance of cane breeding is recognized as the principal approach to countering susceptibility to certain diseases, while some success has attended efforts to produce


new canes which possess a degree of resistance to attack by insect pests.

Discussion of the subject is necessarily limited to a few outstanding examples of pests and diseases with the object of illustrating the methods of control which may thus be summarized :—

(a) The use of poisons for rodents, and possibly insects. (b) Selection of healthy plant material. (c) Roguing—the removal and destruction of infected plants. (d) Varietal breeding for resistance. (e) Biological control.

The Rat Problem The intensity of infestation by rats and the damage and loss

caused by them to the cane varies considerably. In some countries these are negligible, and in others so serious that regular campaigns must be conducted to keep the pest in control. The extent to which rats are a problem in cane areas may to some extent be judged by references to rat control measures in various published reports, and the degree of attention devoted to it, from which it appears that no special measures are taken in many parts of the West Indies, while in Queensland, Hawaii and Florida, for example, the extensive distribution of poisoned baits through the cane areas forms a part of normal plantation routine. The presence of accessible and more attractive food in large quantities has some bearing on the incidence of rats in cane areas, and combined with hard rinded cane varieties which are less easily gnawed than soft cane, often relieves the planter from conducting frequent rat campaigns. The mongoose, introduced from India to numerous cane growing countries in the 1870's and later, has found easier prey than rats and has failed to exercise more than a very limited and localized control.

The damage caused by rats to cane brings about direct loss by destruction of part of the stalk which may be followed by death and rotting, and indirect loss through organisms causing disease which obtain access to the cane through the damaged parts. An established rat population in a cane field is difficult to dislodge, and when this has been effected, re-infestation may soon occur if attention is not paid to near-by breeding grounds. Control measures applied to one part of an area, with neglect of the

F I G . 14.—Seedling nursery, British West Indies Sugar Cane Breeding Station, Barbados.

Fig. 15.-Vert ical photograph of a sugar estate in Jamaica at a scale of 1 /10,000. Natural and artificial drainage systems are clearly seen.

[Courtesy of Hunting Aerosurzeys Ltd.


remainder, will bring about migration with no considerable reduction in numbers. Rats are quick to react to conditions which are unfavourable and dangerous, and whether it be by instinct or intelligence, will defeat any but the most determined and well organized methods for their control. Complete extermination though occasionally possible for short periods seems unlikely to be permanently achieved anywhere. Rodents multiply rapidly, and the few which escape destruction are capable of bringing about the re-population of an area very quickly. Rat populations have been assessed from 10 to 25 with a maximum of 70 in Hawaii, and 30 to 100 per acre in Florida.

Methods of Control

There are several species of rat, each displaying particular habits of feeding and choice of environment. These characteristics should be studied in the planning of control measures, for which three methods are used :—

(a) biological; (b) trapping; (c) poisoning. The biological method depends upon the infection of rats by viruses. This has from time to time been advocated as an effective means of destruction, but in practice it has been found that the initial virulence of disease caused by the organisms used rapidly decreases, as the rats appear to develop immunity. Various preparations of this nature are marketed, but none has demonstrated any superiority to mass poisoning methods, and it has not been definitely established that they are entirely free from danger to human beings and domestic animals. Indeed, cases of illness and death in human beings have been traced to the use of the Danysz and ratin viruses which are amongst those claimed to be lethal to rats. Neither the British Ministry of Agriculture and Fisheries nor the United States Department of Agriculture recommend the use of viruses. Some State Boards of Health in the U.S.A. have prohibited their sale within the States concerned. Preparations containing both a virus and a poison appear to be effective only because of the presence of the poison. For the virus method to be safely used the organism used should be pathogenic only to rats and mice, and so far as is known, no preparation of this nature is available.

' Trapping and poisoning both depend for success on the use of G


bait attractive to the rats both in nature and form. Carbohydrate material—grain, meal, flour, bread and sweet potato are among those successfully employed. Trapping is a temporarily effective measure in and near buildings and habitations when intensively carried out using large numbers of traps, but is costly in labour and quite unsuited to large-scale control as the rats soon learn to avoid the traps. Repeated at intervals of a few weeks, it will keep down the local rat population and possibly cause migration to less dangerous areas, where control will soon become necessary.

Poisoning Methods Large-scale poisoning has proved the most effective method.

It depends for success on a knowledge of bait which will be readily taken, on the use of poisons which are lethal and if possible not harmful to domestic animals and birds and on the conduct of simultaneous campaigns throughout the infested area. In some cases, having ascertained the attractive type of, baits, pre-baiting with unpoisoned material is necessary so that the rats become accustomed to the food and its form. With certain poisons, notably zinc phosphide, the poisoned bait can be distributed at once.

The method used at Clewiston is the distribution by aeroplane of diced sweet potatoes in f-in. cubes poisoned with z\ grams of zinc phosphide per lb. of potato cubes (1 oz. to 11 ½lb.) at the rate of 14.7 lb. per acre. The sweet potatoes are diced and treated in a concrete mixer with the poison and a paraffin wax coating. The aeroplane hopper carries a charge of 700 lb. each trip and treats 420 acres in one hour at a cost of 6 cents an acre for labour, aircraft, and pilot, compared with 67 cents per acre for labour alone by hand preparation and distribution. Corn (Zea mats) is also used as bait, the applications being at the rate of 10.6 lb. per acre of the poisoned material. The usual procedure is to treat standing cane only in February, and to cover all cane fields in June and October.

Numerous other poisons are used and new ones are being discovered and studied. Many of them are general poisons and are subject to the same objections as viruses on that account. Thallium sulphate used with wheat in the proportion of about 1 part poison to 300 of grain is effective, with ¼ oz. (7 grams) per bait enclosed in small weather-proof packages and distributed at the


rate of a few hundreds per acre. In Australia it was found an advantage to spray the baits with linseed oil before wrapping. Great care should be taken in handling Thallium sulphate, which is a depilatory. Thallium sulphate used with a bait of rolled oats has proved of service. Pre-baiting with unpoisoned bait is necessary. Among other poisons used with suitable baits are arsenical compounds strychnine, and phosphorus, but these are dangerous for anything beyond very local use under the most careful control as they are deadly to human beings and animals.

New and potent rat poisons tested in the U.S.A. include sodium fluoroacetate, " Antu " (a-alphanapthyl-thiourea) and " Castrix " (2-chloro 4-dimethyl amino 6-methyl pyrimidine). The hydroxy coumarin compound " Warfarin " has been found useful where rats migrate into cane, and around buildings and houses. It is highly toxic to rats, but is reported to be otherwise safe in regard to accidental poisoning, when used at the concentration of 1 part to 4,000 of bait.

INSECT PESTS

Insect pests of the sugar-cane include those that cause damage by boring into and feeding on the different parts of plant, some of which transmit disease. For example the corn aphis is the vector of mosaic, and the cane leaf hopper carries Fiji disease. The commercial importance of all insects which attack, feed upon or in any way affect cane varies greatly among the sugar-cane countries in the world. Thus, the leaf hopper which carries the infection of the destructive Fiji disease in Fiji and other places, when accidentally introduced into Hawaii, developed rapidly and extensively damaged cane by its feeding habits. The absence of Fiji disease in Hawaii has undoubtedly saved the sugar industry of that island from a major catastrophe, while the application of biological methods has brought the insect under a satisfactory degree of commercial control.

The Moth Borer Among the major insect pests of sugar-cane is the moth borer,

Diatraea saccharalis, which is widely distributed and capable of causing extensive damage when out of control. In some countries, notably Barbados and Florida, special measures are necessary to


deal with the pest while in others, such as the Domin i can Republic and Jamaica, it is kept under satisfactory commercial control by natural agencies, with no attention by the entomologist or the planter apart from an occasional inspection campaign to ascertain the extent of incidence. The female moth deposits i t s eggs on the young cane, and the larvae which hatch out bore i n t o the cane, eat the tissue and subsequently emerge as adults. T h e tunnels thus bored into the cane provide access for disease organisms which often cause extensive secondary damage. T h e method of attack in Barbados and Florida is one of biological con t ro l in the course of which the tiny insects, Trichogramma m i n u t u m , which are capable of parasitizing eggs of the moth borer a r e themselves bred in enormous numbers for liberation in the c a n e fields. In Jamaica the parasite, Lixophaga saccharalis is well distributed naturally and is the principal agency in keeping t h e m o t h borer under control. Where damaging outbreaks of t h e bo re r have occurred in that island they have invariably been t r a c e d to the presence of conditions unfavourable to the normal growth of sugar-cane, such as poor drainage and bad cultivation.

The control of potentially injurious cane insects by paras i tes and predators which are naturally present in the same terr i tory, Is related to the existence of favourable conditions. To continue the distinction between Barbados on the one hand a n d Jamaica and the Dominican Republic on the other, the l a t t e r a re characterized by large expanses of land quite unsuitable fo r cultivation which are covered with wild growths of trees, s h r u b s , grasses and herbs providing breeding grounds and ha rbourage for the enemies of some of the economic pests of the sugar-cane. In the intensely cultivated island of Barbados there are few, if any, areas where such conditions exist. In direct contrast to t h e comparative situation in regard to insect enemies of t h e c a n e is the fact that mosaic disease has been completely e l imina ted from Barbados, while it continues to be a grave problem in Jamaica and the Dominican Republic, a condition undoub ted ly due in part to re-infection from wild grasses which contract t h e disease.

R o o t Ea t ing G r u b s

The grubs of various hard-backed beetles are capable of causing extensive damage by feeding on the roots, and in s o m e cases the


rhizomes of the cane. Important examples are the greyback beetle, Dermolepida albohirtum, indigenous to Australia, the white grub, Lachnostema jamaicensis of Jamaica, and Phytalus smithii which was formerly the cause of great damage and loss in Mauritius.

The Australian greyback beetle has been described as possibly the most destructive insect pest of sugar-cane in the world. It is capable of reducing yields by 15 tons of cane per acre yearly. The adult females of these beetles deposit their eggs at the base of tunnels in the soil. The eggs hatch after 2 weeks, and the grubs develop into pupae after passing through three instar stages. It is during the earlier half of the third instar stage of 6 to 7 months that the grubs, which then may exceed 2 in. in length, feed voraciously on the roots of the cane. One of the modern chemical insect poisons, Benzene hexachloride, or Gammexane, has provided a remarkably efficient remedy, which has almost completely replaced soil fumigation with Carbon disulphide and Paradi-chlorobenzene. The present method is to use a 20% Benzene hexachloride, rock phosphate dust at the rate of 75 lb. per acre, the dust being applied in a band about 18 in. wide over the half-open drills after the cane has stooled, and just before the stool is to be worked towards the cane prior to the field being levelled, the insecticide is incorporated in the soil surrounding the very young cane so that the underground portions of the stalks are protected by a layer of soil charged with the poisonous material which will kill any grubs that may come in contact with it. Various methods have been tried but none has been proved better than this so-called " half open drill " method.

A Catalogue of Cane Diseases J. P. Martin has listed 90 diseases of sugar-cane, and their

world distribution, with the cause of each. Most of them are the effects of known organisms. A few are of genetical origin, some caused by viruses, others brought about in various ways by mechanical, physiological and natural causes, by mineral deficiencies, and II undetermined, among which is the gravely serious Sereh disease occurring in Java and Formosa. The effect of hghtning injury, recorded in Australia, Hawaii, Mauritius, Puerto Rico, and South Africa, may easily be regarded as the result of attack by a disease producing organism, and though listed as a


" disease," is in reality damage by natural causes. There is need for a comprehensive descriptive illustrated work on diseases of the sugar-cane, which would bring together the extensive knowledge recorded by research workers in all cane sugar growing countries. The subject can be discussed here only in respect of a few outstanding diseases, and general methods capable of adoption by the planter under the advice of the local research organization or a plant pathologist experienced in sugar-cane diseases.

Mosaic Disease Mention is made elsewhere of the causes of so-called varietal

deterioration traceable to disease. Mosaic disease almost ruined the cane sugar industry in Louisiana. It has been reported present in 50 countries including all the major sugar-cane areas. An account published in 1919 in the Louisiana Planter recorded that severe damage had been caused by Mosaic in Louisiana and Puerto Rico. The disease had also occurred in Java, Hawaii, and to some extent in Cuba. In Louisiana the cane, especially ratoons, became stunted, but the stimulation of growth by moist warm weather appeared to reduce infection. Some canes were observed to be resistant. The methods of control proposed were the grinding of all diseased cane, the selection of clean seed pieces for replanting, and the removal of all young plants showing evidence of the disease.

Intensive study of the cause, effects and methods of control and prevention of the disease was undertaken by many research workers. The planting of resistant varieties was extensively practised, and the Uba cane, then the major variety planted in South Africa, became widely distributed on that account. The quality of high resistance to Mosaic, observed earlier to be a character of certain varieties, became a major consideration of the work at cane breeding stations, notably at Canal Point, Florida, in Java, and later in Barbados.

Certain new canes bred in Java, notably P.OJ.2878 proved superior in yielding capacity to Uba, being also practically immune from mosaic disease. This range of varieties became quickly distributed to numerous sugar-cane areas throughout the world, and though regarded as inferior from the milling point of view mainly because of difficulties experienced in clarifying the


juice, they were highly popular with planters. Some of the P.O.J. varieties have been successfully used as parents for newer hybrids, which have proved better in respect of yield and other important characters, as well as displaying a satisfactory degree of resistance to disease.

Cause and Effect Mosaic disease is caused by a virus transmitted by the corn

(maize) aphis, Aphis maidis, Fitch. The visible symptoms of the disease are the mottling of the leaf which displays light green and yellowish patches contrasting with the normal dark green healthy tissue. The effect is caused by the destruction of chlorophyll, which is vital to the normal growth processes of the plant. In severe cases, the cane becomes stunted, and yields are depressed. In the past mosaic disease has caused most damage in countries in the sub-tropics where climatic conditions are less favourable to sugar-cane than those of the hot and humid cane areas of the tropics. Curious differences in incidence and effect do, however, occur in countries where soil and climate are most favourable to the cane. Thus Jamaica, where mosaic disease of sugar-cane was first observed in 1920 is still faced with the problem of control, while Barbados, Trinidad, and certain other places in the British West Indies are commercially free.

Certain varieties grown in these islands are commercially immune in some of them, while they contract the disease comparatively easily in Jamaica. In that island a complication is introduced by the fact that the dominant variety, B.34104, which during recent years has rapidly achieved a leading place among the commercial canes grown on sugar estates (as distinct from farmers' lands), is susceptible but tolerant to mosaic disease. This variety may display visible symptoms during the early stages of its growth, which entirely disappear later though the plant itself is still infected. So far as it has been possible to ascertain, its high yielding capacity is not impaired though for practical purposes it must be regarded as 100% infected. Only the future can show whether this characteristic may develop into an epidemic and destructive attack of mosaic disease which will lead to " deterioration " of the variety. In these circumstances it will be readily understood that mosaic disease is for practical purposes entirely


out of control, and that susceptible varieties cannot be economically grown on a commercial scale.

Principles of Disease Control The subject of mosaic disease offers a convenient and outstand

ing example of the methods which are used to reduce and control the incidence of plant diseases. In general these can be summarized into the practice of agricultural methods best suited to crop production in the areas under cultivation, the use of plant material which is entirely free of disease and of varieties which display a high degree of commercial resistance. Bad tilth, poor drainage, uncontrolled weed growth, and the use of unsuitable cane varieties can all contribute to the increase of disease. Special attention to the production of vigorous and healthy seed by establishing nurseries for the growing of the cane which is to be planted is of great assistance. Such nursery areas should be regularly and frequently inspected for the presence of disease, and any infected canes dug up, removed and destroyed, a process known as " roguing." Similar methods after the cane is planted, whereby diseased plants are eliminated, is a common practice, but is not commercially economic when more than about 5% of the total plants display symptoms of disease. When this occurs there are two alternatives : to allow the crop to run through to maturity and plough it out immediately after reaping, replanting with another variety; or to plough out immediately and replant.

Included in the good agricultural practice necessary to ensure healthy crops is the application of the correct dosages of fertilizer, both in nature and quantity; the correction of adverse soil conditions such as the application of dressings of limestone or lime where the soil is acid and calcium deficiency has been determined ; as well as the supply of other mineral deficiencies. Varieties suited to the particular soil and weather conditions of an area, proved in regard to their disease resisting qualities and grown under the best possible system of commercial cultivation, are the best safeguard against damage and loss by disease.

CHAPTER 7

SUGAR-CANE VARIETIES AND PLANT BREEDING

An Epochal Discovery The rate and extent of development of the cane sugar industry

were retarded by numerous limiting factors until the independent discovery made in Java and Barbados in 1887-88, that cane can produce fertile seed, removed the greatest of them. The comparatively few commercial varieties then grown could only thrive in conditions of soil and climate well suited to them. Expansion of cane growing in other fertile soils with apparently suitable environment was defeated by the canes themselves, and by the pests and diseases to which they were prone. The production of new varieties made possible by raising seedling canes proceeded rapidly in Barbados, British Guiana, Java, Hawaii and other places, and a varietal revolution was soon under way by which many of the older varieties were replaced. The planter was thus provided with counter measures to meet the threats of loss and destruction by disease. Up to the time that seedling varieties of commercial value became available, the older canes continued to be popular for very long periods, but since the beginning of the century changes have progressively increased in frequency in almost all cane growing countries, so that what were regarded as standard varieties 15 or 20 years ago in many cases have almost disappeared, having been replaced for various reasons by new hybrids.

Hybridization In the earlier years of application of the discovery that sugar

cane could grow from seed, the new seedlings were derived from varieties actually in cultivation, the so-called " noble " canes. Jeswiet in Java, and Barber in India showed in the early 1920's that these noble canes could be hybridized with more vigorous and closely related species, thereby introducing new genetical factors and enabling the production of new canes possessing greater

95


vigour, improved productive power, and enhanced resistance to disease.

The work of cane breeding is of a highly specialized nature, and can only be conducted with success in places where certain canes flower freely and produce viable pollen. During the past 30 years, as a result of the work of Jeswiet and Barber, the controlled cross--ing of varieties of sugar-cane has been developed so that the parentage of new varieties is known, and breeding work is conducted with a knowledge of the characteristics and behaviour under different environmental conditions of the parent canes. Each cross is capable of producing many thousands of seedlings differing in appearance, growth habit, yield and sugar content at maturity. Apart, therefore, from raising seedlings from hybridized seed, the cane breeding stations need to select, from the large number of seedlings raised each year, a limited number which appear likely to display the characters desired in commercially grown canes. Selection of the better ones, with elimination of those showing undesirable features, is made progressively until a number of them are used for small-scale comparative trials with standard varieties under different field conditions. Those finally emerging successfully go into field scale trials which enable their commercial possibilities to be tested in comparison with established varieties.

Special Qualities Required in Hybrid Canes The planters viewpoint enters into the planning of the work of

the plant breeder, and the recommendations of those engaged in agricultural research on sugar-cane are considered in devising the annual breeding programme of a cane breeding station. Plant breeders themselves must possess a wide knowledge of the environmental conditions of the areas for which they are endeavouring to provide new and improved varieties of cane, as well as being specialists in their own work. Although the sugar-cane is so extensively cultivated throughout the tropical and sub-tropical zones, it is highly selective in regard to the conditions in which it thrives best. Breeding programmes are decided with this in view, and endeavours are made to evolve canes which yield well under particular conditions, as well as canes which, though perhaps not quite so good, possess special characteristics such as resistance to

SUGAR-CANE VARIETIES AND PLANT BREEDING 97

certain pests and diseases. The crossing of wild varieties with noble canes has in this way defeated the threat of mosaic disease. The wild canes are poor in yield and low in sugar content, but immune or very highly resistant to certain diseases which devastate the noble canes. The latter when healthy yield heavily and are rich in sugar. The combination of these characteristics produced the famous Java variety, P.OJ.2878, a vigorous, heavy yielding cane, suited to a wide range of conditions, and commercially immune to mosaic disease.

Why Older Varieties Have Been Replaced In the past most of the replacements of older varieties by

selected seedlings have been brought about by apparent lowered vitality and the serious reduction of yields by disease. In special cases, such as those of Florida and Louisiana where cold weather and frost are encountered in the winter, breeding has produced new varieties which are more resistant to the effects of cold weather. During recent years the capacity of certain new varieties to produce higher yields of cane has introduced this additional consideration affecting decisions to replace canes in commercial cultivation by better ones.

Principal Characteristics Required in Hybrid Canes The basic factors which determine breeding programmes, and

the testing and final selection of the new canes thus produced are:—

(i) Resistance to diseases prevalent in the country for which the selections are made,

(ii) Yield, juice quality, and ratooning power in comparison with standard varieties,

(iii) Age at maturity and time the cane can remain in prime condition in the field,

(iv) Growth habit, (v) General vigour and suitability to soil and climate.

Secondary characters are:—

(vi) Whether older leaves are shed easily or retained-—or trashing habit,

(vii) Suitability for early, mid-, or late-season reaping.'


(viii) Reaction to weather—wind, heavy rain, drought, (ix) Nutrient requirements and responses, (x) Suitability for extended periods of growth,

(xi) Fibre content and milling character.

R e s i s t a n c e t o D i s e a s e This is the dominant consideration in all countries where c a n e

is grown on a commercial scale. The particular diseases to w h i c h high resistance and, if possible, immunity are desired vary widely as will be realized by reference to Chapter 6. Among them a r e mosaic disease in almost all countries, exceptions being the smaller islands of the West Indies ; Fiji disease in Australia, Fiji, Ph i l i p pines, American Samoa, and other Pacific islands (not in Hawaii) ; Smut and red rot in South Africa. Selections displaying o t h e r desirable characters are grown in close proximity to infected plants, or inoculated artificially. Those showing a satisfactory degree of resistance are then tested in comparative trials against standard canes for the observation of other desired characters. It is often found that some sacrifice of yield or other feature is necessary to secure a satisfactorily high degree of commercial resistance to disease. For example, P.OJ.2878, and certain o t h e r Mosaic resistant canes have poorer juices which often c a u s e trouble in the factory clarification process as compared w i t h . Mosaic susceptible varieties, but the disease resistance factor o u t weighs such other considerations.

It is important that the resistance to certain diseases of c a n e s should be tested in the country and under the conditions for which, they are to be finally selected. Most cane breeding stations a r e situated in the country in which their selected canes are to be commercially grown, and comparative testing under different ecological conditions offers no difficulty. The position is pecul ia r in the British West Indies, where the B.W.I. Central Sugar C a n e Breeding Station in Barbados conducts breeding work for t h e member territories, Jamaica, St. Kitts, Antigua, Barbados, Trinidad and smaller islands, and British Guiana, in addition to which selected hybrid seedlings are supplied to other c o n t r i butors. After having been carried on for many years for t h e primary benefit of the local industry, centralization of this w o r k in Barbados in 1932, where exceptionally favourable c l ima t ic


conditions exist for the flowering of the cane and the production of fertile seed, has conferred immense benefits upon the countries which are " members " of the organization. Varieties of cane evolved there are found in most cane-growing countries, either in commercial production, or being used as parents in breeding work. In the past, a number of final selections have been made 6 or 7 years subsequent to the original crossings, after complete testing of all basic characteristics in Barbados. The quality of each selection as determined under Barbados conditions was defined and the expected reaction to disease and other conditions in the country for which they were selected was assessed. Special attention was devoted to Mosaic resistance for Jamaica, and a technique of testing by inoculation was devised. In many cases, new canes selected for Mosaic resistance in Barbados were found to be susceptible in Jamaica. Experience over a number of years showed the desirability of a greater number of selections being tested in Jamaica, and this was accordingly arranged, though the varieties supplied still came from the material from which final selections were made at the Station. Despite the greater range of final selections sent to Jamaica, very few, and in some years none, survived the Mosaic resistance test conducted under field conditions in Jamaica. Conferences between the Station staff and the research workers in Jamaica resulted in a completely new plan, commenced in 1949, whereby cuttings of 500 first-year seedlings were transported by air to Jamaica, where they will be subjected to all subsequent stages of testing and selection. This was repeated in 1950, and will be continued. In addition, Barbados final selections of identified varieties will go forward each year as formerly. It appears probable that in this way, seedlings derived from special crosses made in Barbados likely to confer resistance will be finally selected in Jamaica with greater chances of success.

The vector of the highly dangerous Fiji disease occurs in Hawaii, where susceptible varieties are grown, but hitherto that disease has not been found in the territory. The risk of its introduction is recognized, and is enhanced by the possibility of infection being accidentally introduced by air transport. In this case it is obviously desirable to ascertain in advance of such a possible calamity the reaction to infection of present commercial varieties, and final selections of hybrid seedlings offering commercial

IOO AGRICULTURE OF THE SUGAR-CANE

possibilities. American Samoa was chosen in 1947 for the testing in this manner of canes of commercial promise selected for Hawaiian growing conditions.

Cropping Characteristics Yield, juice quality, and ratooning power of new and promising

hybrids are compared with those of standard canes in commercial cultivation. Ruthless elimination occurs in the earlier selections and those which survive are regarded as being likely to compete with canes which have already proved themselves. Small scale field trials under varying conditions of soil, rainfall, and other varying factors if present are conducted in replicated plots, the final selections for commercial scale comparisons being made from the ratoons. Occasionally selections are made on the basis of the behaviour of plants, but in general the capacity for good ratooning is of major importance. These investigations may be combined with observations on the optimum age at maturity and the length of time the cane continues in good condition during the reaping season, both of which are important in connection with the crop planning and reaping programme of canes in commercial production. The relative vigour, and suitability displayed for the different soils and climates encountered in the cane lands of the country will emerge from these trials. Some hybrids are much more selective in their requirements than others, the latter being known as general purpose canes, which thrive and yield well under a wide range of environmental conditions.

The miller is interested in processing cane of uniform quality, good milling character, high in sucrose, medium fibre, easily clarified juice, and maximum sugar recovery throughout the milling season. When cane is purchased on the basis of its sucrose content, or on the recoverable sugar, it is greatly to the planter's interest to supply such cane. Here again the plant breeder has been able to render remarkable assistance by evolving high yielding canes with a satisfactory commercial resistance to disease which mature at different ages, as well as others which will remain standing in the field in good condition for several weeks.

The small scale field trials in which these various cropping characteristics are examined must be conducted with the greatest care to ensure that true comparisons are made with the standards.


This work sometimes gives results indicating that certain new varieties are greatly superior to the standards, but such conclusions are not confirmed by subsequent field scale trials. This may be due to the careless selection and treatment of seed pieces from the standard varieties, or to a tendency on the part of field assistants to devote closer attention to new varieties at the expense of the standards. The whole of such investigational work requires constant high level supervision, which must be particularly vigilant at the time of harvesting.

Growth Habit This term broadly includes tillering, appearance, the shedding

of trash, and reaction to adverse weather conditions. Tillering or stooling is assessed by the number of stalks developing from the primary shoot which grows from one eye of a seed piece. Tillering capacity has much to do with the appearance and yield of cane. Heavy tillering combined with vigorous growth is a desirable feature. The cane stalks themselves grow in different ways, some being erect, others curved, partially recumbent and occasionally tangled. Canes which grow outwards from the stool and then continue straight in an upward direction while not ideal, are not objectionable. Recumbent, tangled cane is highly undesirable. Even with satisfactory yields it is troublesome to reap. Erect cane is essential to successful mechanical reaping, and popular with manual cutters. Colour is unimportant.

An otherwise satisfactory hybrid would not be rejected because of adherence of the dead and older leaves to the stem. A free trashing habit is, however, an advantage in certain circumstances. An example of a high yielding and popular hybrid, which retains its trash, is B.37161 grown extensively in the West Indies and recently introduced into Mauritius. In very wet conditions the eyes may grow and roots develop from the stem nodes, as in the wet areas of Mauritius, where the variety has to be manually cleaned of trash to prevent this occurring. The old leaf sheaths attached to the stem render it more liable to damage by the moth borer which is thus partially protected from the egg parasite Trichogramma minutum bred and distributed in Barbados for the biological control of the pest.

Adverse weather conditions include high winds and excessive


and deficient rainfall. High winds may cause snapping of the stems and uprooting of the stool. Toughness and resiliency, combined with deep vigorous root development characterize those varieties best able to withstand heavy windstorms. B.3439 and B.4098 are both heavy yielding canes w i t h excellent milling qualities, but their shallow rooting habit causes them to be blown over and uprooted in moderate windstorms, particularly when the soil is wet. The former usually continues to grow by the rapid formation of a new root system, but the latter dies.

Excessive rainfall in well-drained land produces heavy growth of cane, but may retard or prevent the cane f r o m ripening. If the water table is high the effect on maturing is accentuated, and though comparatively high cane yields are obtained, the sugar content is low. These conditions occur in t h e north-eastern and eastern districts of Jamaica where cane yields consistently exceed the Island average. The factory in the former area is mainly dependent on farmers' cane, so that it cannot exercise the same degree of control over cane quality as can t h e one in the eastern area where these conditions are reversed. Sugar yields per acre in the latter are usually slightly above the general average. There are other factors which affect the comparison between the two areas, but the major consideration is rainfall and unfavourable ripening conditions. The hybrid cane B.37172, thrives in both areas, where it has proved more suitable t h a n other varieties, though very little of it is grown on other estates in Jamaica.

Tolerance of droughty or deficient rainfall conditions is important in places where the rainfall is not well distributed, is considerably below the optimum for the cane, a n d where irrigation is not practised. While no cane is in t h e t r u e sense drought resistant, certain varieties survive and yield comparatively well in areas of low rainfall. An outstanding example is that of Natal where the annual rainfall averages barely 40 in . with considerable variation from year to year. The canes are grown through two rainy seasons and are therefore about 2 years o ld at reaping. The winter season is dry and growth is retarded. The cane grows rapidly again with the onset of warmer weather and the spring rains. The annual average sucrose per cen t cane at reaping exceeds 13, and is often more than 14. Coimbatore varieties notably C0.281 (47.3% of total tonnage r eaped in 1949-50) and


C0.301 (41.89%) are the principal canes grown. A new variety N: C0.310, selected in Natal from seedlings grown from fuzz imported from Coimbatore is rapidly coming into favour.

The sucrose content of the cane at reaping is an important factor in determining planters' financial returns. It is now invariably the basis upon which cane prices are computed. Obviously, for similar tonnages of cane per acre, the richer canes pay better. In the recent past the estate owner and the plantation staff thought mainly in terms of cane yield. In many places, particularly in the West Indies, a contract price per ton of cane was paid irrespective of quality, or market value of the extracted sugar. Purchased cane is now bought at rates which depend upon the amount and value of sugar obtained from it, and the cane farmer appreciates the desirability of growing canes which are high yielders of sugar. A factor often overlooked in this connection and illustrated in the table is the comparative effect of cane quality upon the cost of the cane delivered to the mill acceptance point.

Cane, tons Sucrose % Sucrose per Approx. increase in harper acre cane acre, tons vesting costs above

standard

Assuming that the variety grown, under normal conditions of cultivation, manuring, rainfall and age at reaping produces cane with an average sucrose content of 12.75%. This at 40 tons per acre yields 5.1 tons sucrose. To obtain the same gross return per acre at 8.5% sucrose involves reaping, loading and transporting 50% more cane, requiring an equivalent increase in the costs of those operations which reduce the net profit. That, powever, is not the only effect. More men and more equipment are needed to move the same crop in terms of sugar. Office, supervision, and depreciation charges are higher. Apart therefore from the practice

H


of good husbandry, it is essential that cane varieties shou ld be selected in regard to their suitability and yielding power in terras of sugar for the different soils, weather conditions a n d other factors which influence growth and maturity.

Response t o Soil T r e a t m e n t a n d M a n u r i n g In field trials against standard varieties from which t h e final

commercial selections emerge, cultivation and manuring are the same for all the plots. After the best have been chosen, it is necessary to investigate their response to modifications of cultivation methods indicated by their growth habit and yield, and to fertilizer applications at different levels of N, P & K. As in the selection trials, these comparisons are made against s tandard canes, as well as between the new varieties. This work should n o t retard promising new varieties from going into commercial production as soon as they have been proved in regard to disease resistance and other desired characteristics. The procession of n e w and improved types coming forward in all progressive sugar-cane countries involves continued investigation of their reactions to standard cultivation and manurial practices and to variations of them with the object of bringing about the highest possible commercial yields consistent with costs and profitable re tu rns . Behaviour of the cane under irrigation is important where that is practised.

A g e a t Reaping

The special conditions of Natal have been briefly mentioned but there are other places, notably Hawaii, where plant canes and ratoons are not reaped until they are 22 to 24 months old, or even more. Soil, climate, cultivation, and irrigation are contributing factors to this, but the varieties of cane are of some importance. The yields of sugar per acre compared with those of o ther tropical countries are proportionate to the extended period of growth. The advantages of the method are the great reduction in preparation, cultivation and planting costs in relation to the quant i ty of sugar produced. On the other hand, higher costs for irr igation can be sustained.

There is great variability in the age at maturity of hyb r id s , and in their ability to maintain both sugar content and ju i ce quality


for shorter or longer periods. This enables selections to be made of new varieties suitable for planting at different times of the year to mature at varying periods of the milling season.

Technique of Hybridization While there is considerable variation in the technique of hybridi

zation, the foundation of the work is the same at all cane breeding stations. Success in the production of fertile seed from the selected parents depends upon the shedding of ripe viable pollen from the male on to the receptive stigma of the female parent. It is therefore necessary that the station be situated where the canes flower or " arrow " freely, with the production of ample supplies of pollen from those chosen as male parents. The sugar-cane is hermaphroditic, the flowers having both male and female organs. Some canes are predominantly male, or female, and those which are to be used as females must not produce active pollen.

The crossing must be carried out when both the male and female tassels or flowers are in the correct condition, which is determined by observation. The sugar-cane does not flower in any regular manner, so that it is impossible to conduct the work by planting male and female parents in proximity to one another. In practice the cane with male flowering head is cut, the cut end placed in a preservative solution and carried to the female, where the pollen when in ripe condition is shaken off. Another method, used in Hawaii, is to cut both males and females, carrying out the crossing in a place remote from other flowering canes. The preservative solution used in Hawaii contains 0.01% of sulphurous acid and 0.01 % of phosphoric acid. In Mauritius no advantage has resulted from using phosphoric acid, and sulphurous acid is used alone at a strength of 0.03%.

Protective Measures In some places, notably Barbados and Mauritius, the female

flowering heads are enclosed in a form of lantern, with glass sides, the object being to prevent accidental pollination. The male flowers, with their fully developed pollen are introduced into the lantern and shaken so that the pollen is shed to the females. This work is conducted in the early morning because at this time the pollen is shed freely and the stigmas are receptive. Another


method is to place the male flower in the lantern before the pollen is shed, with its cut end in preservative solution, leaving it there until all the flowers of the female arrow have opened and died off. The female is then enclosed in a muslin or similar bag so that the seed may ripen and no loss occur by wind.

Germination and Transplanting The seeds, which are extremely small, do not keep well and the

usual practice is to plant the " fuzz " removed from the arrow in shallow trays or flats containing sterilized compost soil. Germination is stimulated by warmth and moisture, and it is necessary to keep the atmospheric humidity high. The seeds germinate and produce shoots similar to young grass after a few days. A common practice is to transplant them into individual pots after about 6 weeks, care being taken to identify the young plants from each cross (Fig 14). The plants are grown in the nursery for a period of 8 to 10weeks afterwhich they are put out into the field, the spacings varying in the different countries. In Mauritius, for example, rows are planted 4 to 5 ft. apart with 2½ ft. between plants in rows, every fifth plant being a standard variety of the same age,

The first selections from the many thousands of these first year seedlings are made about 1 year after the original planting of the seed.

The Special Conditions of Natal The most recently established breeding station for the produc

tion of hybrids from local crossed varieties is in Natal. Until recent years new introductions of cane were made in the form of cuttings which were grown under quarantine conditions until the first ratoon crops had been obtained, when if free from disease they were released to the experimental station of the South African Sugar Association for testing under field conditions. The Coim-hatore varieties having been found particularly suitable, the farther step was taken'to introduce " fuzz " from Coimbatore to be carried through all subsequent stages of selection in Natal. TMs has brought about several promising new varieties, one of which, N.C0.310, is outstanding. In the course of this work the factors which limited the production of fertile seed under Natal conditions were investigated.


Seed from commercial types growing in Natal was first successfully germinated in 1944. It was known that the failure of the pollen to ripen under natural conditions "was the principal cause of the non-production of fertile seed among the varieties which produced flowers. The investigation finally resulted in the disclosure that low temperatures and humidity were the conditions which limited the maturing of the pollen. It was found that canes cut at the time that the pollen was just being produced could be induced to mature their pollen if they were kept in a chamber where the temperature and humidity were controlled and maintained at certain levels. The preservation of the cut stalks of cane was effected by dipping the cut ends in a preservative solution, and enclosing a node above the container with a moist compost of cane trash enclosed in a tin.

This discovery has opened up great possibilities for the production of fertile seed from controlled crossings which are conducted in the compartments of a specially constructed glasshouse erected for the purpose. The arrowing male and female stalks are kept together in the manner described in single compartments in which temperature and humidity are automatically controlled, until the seed is set and mature. The subsequent stages of sowing and transplanting follow the general practice elsewhere, except that unlike Barbados, the flats in which the fuzz is germinated have to be kept in a glasshouse where the proper levels of humidity and temperature are maintained.

The procedure after the first year seedling stage follows an increasingly intensive system of field testing and comparison against standard varieties under the different environmental conditions until the final selections for commercial trial emerge 6 to 7 years afterwards.

Approval of New Varieties The sugar-cane planters throughout the world need no persua

sion to convince them of the vital importance of sugar-cane breeding with the object of producing new hybrids of commercial planting value. The danger is that those in charge of plant breeding operations and die subsequent exhaustive testing are continually pressed to release new varieties before they are fully proved, and before it is safe to do so. Indeed planters have been

I 0 8 AGRICULTURE OF THE SUGAR-CANE

known to help themselves to cuttings of what they regard to be promising new varieties undergoing tests before they have passed through the complete investigation cycle and have been approved for release. In some countries the necessity for protecting the planter against the results of his own enthusiasm has been met by local enactments whereby only approved varieties of cane may be planted, and any infringement of this is a breach of the law. This official approval of new varieties before they are released for commercial planting protects the whole industry of the country concerned against the risks of propagating undesirable and disease susceptible varieties. It is sometimes found that the control extends to the approval of all varieties for planting even if they have been in commercial production previously. The intention of such a far-reaching system is to bring about the elimination of varieties which have formerly been satisfactory, but which have developed undesirable characteristics, particularly susceptibility to disease, which might harm the industry.

Breeding Material For some years new hybrids produced from controlled crossings

have themselves been used in cane breeding, and these with the wild varieties of cane provide the plant breeder with a wide range of material upon which to work. The ever increasing variety of available parents is on the one hand a direct result of previous breeding work and on the other is derived from the wild canes which themselves are of various strains. Breeding stations constantly endeavour to expand the diversity of their cane varieties by importing those which have been proved useful in other countries or which appear to offer possibilities as new parents. The study of these parent canes forms an important branch of the work of a cane breeding establishment. In addition to the exchanges of material, special expeditions are organized from time to time to seek for additional wild varieties. The most recent of these visited New Guinea in 1951 to endeavour to find new material for the Bureau of Sugar Experiment Stations, Brisbane, Australia. In the course of the search 100 native varieties were found and despatched, including a giant variant of Saccharum robustum (designated 51 N.G.91) which has a higher sucrose content than usual for this variety. The effects of this work only


become apparent after several years, but the high importance of past scientific excursions of this nature can be judged from their profound and far-reaching results.

Some Varietal Changes One result of this is that in most countries very much greater

numbers of different varieties are in commercial cultivation than formerly, with one or two holding a dominant position. This is particularly well exemplified in Jamaica where a greater range of soil and climatic conditions for sugar-cane exist than probably in any other cane growing area. In 1940 the dominant cane was B.H.10/12, occupying over 40% of the total acreage, followed by P.O.J.2878 with 20%. Although at that time new Barbados seedlings were under test, their individual acreage was small


when they were classed with " others." In 1948 B.H.10/12 and P.OJ.2878 together represented less than 15%, while B.34104 with 46% and B.3439 with 2 1 % had replaced them. Some varieties grown on comparatively small areas in 1940, including E.K.28, Uba, P.OJ.2725 and S.C.12/4, had completely disappeared by 1942. The changes over 5-year periods for the whole island are clearly shown in the diagram from which it will be seen that at least 75% of the cane grown in 1949 consisted of Barbados hybrids.

In Hawaii the Lahaina cane, which began to fail in the '90's, had almost disappeared by 1923, 10 years after the beginning of the varietal changes from the previously grown commercial varieties. For some time yellow Caledonia increased but by the late '20's this had practically disappeared. D.1135 became popular for a time but went out of cultivation about 1920, by which time H.109 was coming into prominence, subsequently attaining the dominant position which it held for many years. By 1938 this was being progressively replaced by new Hawaiian hybrids. It will be clear from the discussion of commercial varietal changes that further decline in some varieties and popularity in those now under test and still to be produced will continue to be a feature of the cane sugar industry.

The extent of sugar-cane breeding is indicated by the following table, which provides a key to the places where new varieties have been produced.

ORIGIN OF CANE HYBRIDS

A. _ Antigua. B. _ Barbados. Ba. .. Barbados. B.H. .. Barbados Hybrid (seedlings of proved parentage). B. .. After a number, which is usually preceded by J,

seedlings raised by Bouricius in Java. B.O. .. Province of Bihar and Orissa, India. C.H. .. Cuban Hybrid. Co. .. Coimbatore, India. C.P. .. Canal Point, Florida, U.S.A. D. .. Demerara (British Guiana). Diamond Diamond Plantation, Demerara (British Guiana).

The Apparent Deterioration of Varieties The sudden failures of the Bourbon Cane in Hawaii, West

Indies and British Guiana towards the end of the nineteenth century, and more recent cases of apparent loss of vigour and reduction in yield are often ascribed to deterioration due to the variety having been commercially grown for many years. Experience has shown that other varieties grown over a long period show a falling off in yields, and an increased susceptibility to diseases, particularly those which affect the roots. The Bourbon or Lahaina Cane in Hawaii succumbed to root disease after having retained a leading place amongst the varieties grown for nearly 50 years. The same variety failed spectacularly in Antigua in 1895 from an attack by what was called a rind fungus. This nearly caused the complete failure of the sugar industry, which was saved by varieties resistant to the fungus. The Barbados variety, B.H.10/12, which


until quite recently was the leading commercial cane in many parts of the West Indies, is regarded by most planters as having deteriorated because it appears to succumb more easily to pests and disease and displays lack of vigour and poor yields under conditions in which it formerly flourished.

In the past the principles and technique of maintaining and improving soil fertility were not understood or practised as they are to-day, so that the cane was not provided in successive planting cycles with the most favourable growing conditions. Tilth and fertility level were in many cases contributory factors to apparent deterioration as the reduced vigour of the cane thus induced provided more favourable conditions for attack by disease causing organisms. The careful attention to the selection of planting material, which is now more widely given, was not then practised, with the result that setts from unhealthy and poorly developed old ratoons were generally used instead of healthy material from well grown but immature plant cane. It is believed that organisms present in the soil, which affect the roots of suceptible varieties may thus undergo progressive changes which bring about an increase in the soil population capable of attacking canes which in earlier growth cycles have displayed resistance. The development in this way of specialized forms of organisms causing disease, in association with particular varieties of cane, has been discussed by G. C. Stevenson, who points out that any which find a suitable medium in those varieties will increase at the expense of others and in time cause a greater amount of damage.

Experience has demonstrated the undesirability of complete dependence upon one or two varieties of cane, and the unremitting search for improved varieties conducted at cane breeding institutions has provided the planter with a greater range of commercial canes, of which he continues to take full advantage. Many of the previous failures can be ascribed to attempts made to grow a single variety of cane under widely different environmental conditions, to many of which it was quite unsuited. This also may well be regarded as another contributory factor to supposed deterioration.

CHAPTER 8

PLANTATION AND FIELD PLANNING

Importance of Planning It may perhaps be thought that discussion of planning is

redundant when applied to an industry so long and so widely established as sugar-cane agriculture. Modern advances in agricultural methods and the amalgamation of smaller plantation units into groups under single control make it necessary to redesign layouts with their internal systems of roads, drains and fields. Such work is often more difficult than the problem presented by an entirely new venture, involving as it does the continuance of crop operations during the period of reconstruction, with the minimum of dislocation.

Progressive Amalgamation of Estates In parts of the West Indies where sugar-cane has been a major

crop for almost 300 years, plantation units of to-day have developed by progressive amalgamation from very small estates, each with its sugar works and distillery, to organizations with modern central factories and cane areas which might easily be measured in square miles. Thus in Jamaica in the closing years of the eighteenth century there were more than 1,000 independent self-contained small estates with a total output of less than one-third of the near 300,000 tons of sugar from the 22 mills now in operation. Old landmarks such as drains, canals and aqueducts, sites of works, and locations of great houses are distinguishable to-day, and still have the imprint of the careful work carried out by their owners of long ago. Matters like wayleave for road traffic, water for the " works " and drain discharge were troublesome and contentious. Each estate had its access to the sea and its barquadier or loading place for ships, often no more than an open beach. Without these its produce could not be shipped, and incoming supplies could not be landed. Main drains of adjoining estates sometimes ran within a few feet of one another on each side of the common boundary. Fields were small and irregular in shape. The works, slave quarters, cattle pens, and farm buildings were in

113

1 1 4 AGRICULTURE OF THE SUGAR-CANE

a close and compact group, dominated by the great house nearby, the residence of the owner or his attorney. Judged by our standards, waste and inefficiency characterized the industry, but labour was cheap and the value of sugar and rum high, so profits were made and apparent contentment prevailed.

Successive waves of economic pressure on the one hand, and improvements in field and factory practice on the other, brought about the establishment of the so-called " centrals " of the late nineteenth and early twentieth century, forming larger groups of sugar-cane farms from those amalgamated in earlier times. The significance of the term " central" soon underwent a change in the direction of bigger groupings, some of which came into bemg in St. Kitts, Antigua, Jamaica and Trinidad during that period to be followed more recently by further similar developments in Jamaica and Trinidad. All these movements entailed some re-planning, but little change seems to have occurred in field layout until mechanical methods began to replace the use of animals in cultivation and estate haulage work. The phase of field mechanization which first became evident when steam ploughs were introduced has rapidly transformed the layout and operational patterns of cane plantations during the past 25 years, since the diesel-powered track laying tractor became available for agricultural work. Large irrigation and drainage projects in various places also contributed to the development of modern sugar-cane plantation layout, with rectangular fields and internal road and rail systems of regular design. In Jamaica the replacement of the banana, which reached the zenith of its production in 1937, by sugar-cane has necessarily been accompanied by some re-planning of several large plantations. Expansion of the sugar industry in many countries has brought large areas of new land under sugarcane, involving careful attention to this matter.

The main principles of planning are similar for both phases of the subject, but the extent to which they can be put into practice is limited in the case of a plantation already in existence. On the other hand the experience of earlier years, and the knowledge gained of the productivity of the land, the problems of drainage, and of numerous other matters which affect the success of farming operations enable redesigning to be carried out .with certainty of success.

PLANTATION AND FIELD PLANNING 115

Land Survey The first essential to any planning project is an accurate and

detailed survey, with levels at vertical intervals which are determined by the configuration of the land, ranging from 1 ft. in flat land to 5 ft. or more in sloping and hillside land. The survey should show all natural features, as well as roads, tracks, drains, and buildings.

A e r i a l S u r v e y s Aerial surveys are being used to an increasing extent. They

give a photographic representation of the land surface as seen from above to convenient scales, and record every marked feature visible from the air (Figs. 15 and 16). They are carried out quickly, accurately and comparatively cheaply. The photographs prepared from them are used for the preparation of survey plans similar to those which result from surface surveys (Fig. 17). Supplementary work is required on the ground. The location relative to other areas and the scale are determined by using a few prominent fixed points which show clearly in the photographs, of which the positions and accurate distances apart are known. Contours at intervals of 5 ft. can be shown on plan from the photographic survey, but in the case of flat areas, especially where irrigation and drainage works are to be constructed, more accurate levelling must be done by instruments on the ground.

An outstanding advantage of this type of survey work is the photographic recording of certain useful features which are barely if at all distinguishable from surface observation. Among those of help in the planning of sugar-cane estates are old water-courses and drains, sites of former dwellings and works, evidences of previous cultivations, traces of roads and tracks, and differences in vegetative growth caused by soil and moisture variations.

Observations on the Ground Ground reconnaissance is used to provide information regarding

the nature, variety and extent of vegetation, to observe differences in types of soil, and to select areas for priority of development. At the same time visual soil observations are made at depths down to about 2 ft., using a soil auger or other convenient tool. On the results of these, points are selected for soil pits, and for samples

I l 6 AGRICULTURE OF THE SUGAR-CANE

to be taken to be examined in a laboratory. Obviously this work should be carried out by a soil scientist. These surface observations, supplemented by the results of soil examinations are now considered in relation to the survey previously completed, and the first stage of actual planning proceeds.

The Focal Point In the course of this preliminary work, what may be termed the

focal point of the plantation is determined. For an entirely new project this will be the site of the sugar factory if one is to be erected, or already exists to receive and process the sugar-cane. Should the project be a cane farm for supplying to a factory some distance away, the focal point will be the outlet from the farm to a public or other road, or to a railway siding as the case may be. In some cases it might be a loading point on a water-way. The whole outward movement of cane from the fields and the inward movement of machines, implements, materials and field personnel should now be considered in relation to this focal point.

General Requirements At the same time, main drains and canals, if irrigation is to be

practised, should be planned. The result of this will be the completion of the second stage, with main roads and tramway traces, main drains, and irrigation canals. If water for irrigation is to be conveyed by pipes, the pipe lines will take the place of canals but will not necessarily be similarly located. The land contours need careful study in connection with this part of planning, more particularly with main drains and canals, which must be related to the actual field requirements in both cases, the former for the unrestricted movement of surplus water into the drains and the latter to enable water to be applied in controlled quantities when needed. The positions of rail and tramway sidings, hoists and weighing stations, farm buildings of various descriptions, staff residences and labour quarters should be selected and demarcated. In some instances it may be possible to select sites on ground not suitable for sugar-cane, without interfering with a practical layout, but the primary consideration should be the efficient operation of the plantation from the view point of sugar-cane growing.

When bush and woodland areas exist, it is desirable that the


plans should provide for the retention of some portions of them, particularly if they occur in poorer types of soil and in sections where there are commons useful for grazing. Such reserved areas need not interfere with the layout of roads, railway, drains, or irrigation works.

The possibilities of impeded drainage caused by roads, canals, the railway permanent way, sidings and other places where consolidated earthworks are to be constructed, should as far as possible be foreseen, provision being made by culverts and other relief measures for the free movement of drainage water. The location of main drains, canals and tramways is determined very largely by the configuration of the land and particularly the contours. Greater freedom of selection is possible for the main internal roads, though these should be so laid out that the subsequent field subdivisions fall into a regular design of rectangles of uniform size except where other features prevent this. Subsidiary surface drainage should fit into the same pattern.

Thus the subsidiary drains follow gentle slopes from the fields to the mains, the fields being so laid out that they drain naturally into the subsidiaries. In level and flat land—using the terms in the sense of level land having practically no slope and flat land a very gentle slope, being in fact a slightly inclined plane—fields can be easily laid out in rectangles of strictly uniform size. Steeper land, ranging through varying degrees of slope to hillsides, is more difficult to plan and does not lend itself to regularity or uniformity of design. With such terrain the protection of the soil from erosion is a major consideration. Careful levelling by instrument to plot contours is an essential preliminary to laying out roads and drains, which must run at a small angle only to the contour, with protective works at hillside turns. Tramways in such land also closely follow the contours and their traces are planned in accordance with the principles of railway engineering.

Cane Fields The size of fields is determined by the extent to which mechani

zation of agricultural operations is practised, the rainfall, and whether surface irrigation is conducted, as well as by the general configuration of the land. Fire risks and control should exercise some influence. In the Florida Everglades, where there is no


surface irrigation, the fields are 40 acres in extent, and they fit into a rectangular pattern of mile square sections (Fig. 2). Estates in Jamaica in the dry area, using surface irrigation, have fields ranging from 8 to 15 acres. In the wet districts, the size rarely exceeds 10 acres (Fig. 17); and in some areas is even smaller because of the necessity for closer drains. Small fields are also characteristic of districts where manual cultivation methods and animal drawn implements are largely used. No rule can be laid down for optimum field area, and so long as the conditions for economical and successful production are met, considerable variation is possible.

Roadways, Tramways and Field Intervals Easy access to fields, with facilities for free movement of

personnel, equipment, supplies and reaped cane are provided by intervals or traces between the fields and subsidiary roads which lead into the estate main road system. When tramways, with portable temporary feeders laid as required, are used, they largely replace the roads, but the field intervals are still necessary, as they provide for the rail tracks, as well as for the movement of tractors and implements. Drains and irrigation ditches will in general run at the side of these traces and subsidiary roads. The width of the intervals or traces, which thus separate fields from each other, will vary in accordance with the purposes to be served. An important consideration is fire control, which is assisted by wide intervals. On the other hand, the planter desires to put his land to productive use, and subject to the convenient conduct of field operations, is inclined to reduce the area taken up by roads and intervals to the minimum. The smallest interval width should provide space for a shallow drain on each side, and allow for the passage of a motor vehicle, such as a small four-wheel drive light truck, when the cane is fully grown. It will be seen that the choice of interval width is governed by working requirements and personal judgment, and that the general pattern will be narrow traces between individual fields running into wider ones serving groups of fields which in turn connect with the subsidiary and main road system, with a similar design of tramways are used.

The broad outline of planning now includes all but the internal layout of the individual fields, which is discussed in Chapter 5, but there remain some details to be considered. It is clear that


freedom of movement is not only needed for men and materials, but for water, whether it is to be used for irrigation or removed from the land by the drainage system. Impedance of drainage has been mentioned in relation to consolidated earth work, but the permanent drainage and irrigation plans must provide for water crossings at numerous places in the system of roads, railway and intervals. These should be provided by bridges, culverts, pipes and siphons, in accordance with the special needs of each case. The design and construction of these works should be such that they will withstand the movement of tractors and other heavy loads, and are not liable to become choked with floating debris or silt.

An important point in the layout of flat and level lands is to arrange groups of fields in line with unobstructed intervals between them, so that major preparation and planting operations can be continued on long runs from field to field through the intervening traces, which are restored when the crop is established. This reduces lost time and heavy wear on machines and implements at headland turns.

Methods of cane delivery vary considerably, ranging from a road system with animal or tractor drawn carts, to a standard gauge railway, so that the planning of the transport facilities depends upon the particular practice in use. An essential for all of them is provision for accurate weighing of all loads whether of cane or miscellaneous materials. Some of them require means of quickly transferring loads from one vehicle to another. All need places where vehicles can pass each other in safety, and where numbers of them can be left standing without interfering with traffic. The question of space occupied by other things than growing cane again arises, but though economy in the layout of transport works is desirable like any other aspect of the job, it must not be exercised at the risk of congestion and restriction of free movement of traffic.

Road-Rail Transport Plantations which have railway systems need road systems

capable of conveying traffic to the railway loading points, and suitable arrangements at the latter for dealing with it. At carefully selected points, railway sidings are put in, with ancillary equipment comprising a weigher and a transfer crane or hoist. The


siding itself should be of adequate length to take a complete train of cars and should be of the " passing " rather than the " stop-end " type. The weigher and hoist should be sited to operate at the siding leaving the main line clear. They should be surrounded by a yard with well-ballasted foundation and ha rd surface, of sufficient size to accommodate the maximum road traffic, inward, outward, and resting, likely to be experienced, and to allow it to move in and out without obstruction. If a platform scale is to be used, it should be located at a point where incoming traffic enters, with space between it and the transfer hoist to allow loaded vehicles room to wait when necessary until they can proceed under the hoist for discharge. The siting of the hoist requires care, and it must be in proper relative position to the railway siding, being so erected that loads can be accurately placed in each rail car as it comes beneath. Some types of hoist have swinging booms, and others a travelling overhead carriage. Both should have space for placing loads on the ground so that cane may be stored if rail cars are not immediately available, and road vehicles released quickly. The weigher may be incorporated with the hoist, in which case no separate scale house and platform machine is required. Good lights for night working are necessary.

Tramways and Railways A common type of light railway is of 24-in. gauge, and portable

track is used to convey cane from the fields to the permanent line. The latter requires passing sidings at carefully chosen points, but transfer of loads is not necessary. Yards with hoists or other equipment are therefore not required. Provision for weighing is desirable, and can be made by a scale in the rail track at a convenient point over which all traffic can pass, with a passing siding to avoid locomotives having to move over the weigher.

Survey Plans or Maps The various essential works and field subdivisions having been

decided, a scale plan or map should be prepared for the whole, with supplementary detailed drawings for bridges, the larger culverts, road and rail crossings, building sites, railway sidings, and all major requirements. Before any permanent construction is begun, the sites of all major jobs should be located on ground,


using instruments in accordance with survey practice. These matters require the attention of an experienced person. Corrections of some observations made in the original survey may be necessary as a result of the re-checking which should be done at this time. It should not, however, be necessary to delay all field work connected with land preparation and planting, which can proceed concurrently with other operations in the areas selected for first development. These will usually be sections where drainage and irrigation can most easily be provided, and which fit into a scheme of plant-ratoons crop cycle.

The completed estate plan will be kept for general reference and guidance in the progressive development of the whole, being altered and added to as the work proceeds. Separate plans should be drawn for particular works, such as main and subsidiary irrigation canals, or piping system ; roads ; railway ; and main drainage, so that minor works related to each can be designed and constructed in relation to the whole. Staff who need to use the plans or portions of them should be provided with prints, the master plans being retained in the office and used only by an authorised person, who should be the estate civil engineer or surveyor. The information recorded on the plans should enable the exact location, nature and extent of all works to be known. Field areas are among the important data used in computing acreage yield and costs, and must therefore be accurately determined. If underground water is to be used for irrigation, well sinking will proceed at selected points during the preliminary stages of survey and planning, as the position of successful wells will be a factor in determining the layout of the water supply system and of the fields. These matters are discussed in greater detail in Chapter 13.

Planning for Non-Irrigated Areas The planning of non-irrigated plantations, and of extensions to

existing ones is conducted on similar lines. In high rainfall districts closer attention to the drainage of roads, railways, loading sidings, and farm buildings, is necessary, sites above average land level being chosen wherever possible. Expansion projects associated with established plantations often offer opportunities for improved lay-out as compared with the existing one, though


major works may have to be connected wi th or related to those already in use ; railways, for example, must be of the same gauge and load capacity throughout if trouble is to be avoided.

Airfield The use of aircraft, of both the fixed and rotating wing types is

becoming a feature of normal plantation operation, as well as a means of convenient and fast transport for estate personnel. The provision of a suitable landing strip for light aircraft should therefore receive attention.

Merging of Small Plantations When older types of plantations are to be redesigned, survey

and planning are quite as important as with, the kind of project already considered, but in addition the most careful study of the existing layout should be conducted, preferably for a period under actual operating conditions. Cane planters of the past had good reasons for what they did, and though cane varieties and agricultural methods have changed, much of their earlier works are of value to-day. With many such estates t h e planning necessary often takes the form of consolidation rather than complete redesigning, with the provision of works required to bear the heavier modern traffic, and field sizes more suited to present methods of cultivation. The need for work of this description sometimes arises from a grouping of plantations or estates formerly owned and operated independently. The smaller individual self-contained units, each with owner, staff, mill and equipment, lose their identity as such, and merge into a greater undertaking under unified control, haying a single large central factory, which becomes the focal point of the group. The normal staff of such an organization includes men who by training and experience can undertake successfully the work of replanning to meet the new conditions.

It has been slated that in former days there was little or no cooperation or connection, even between adjoining estates with common boundaries. The effect of this upon the Consolidation of a group is profound, more particularly on m a i n roads and drains. One of the first requirements is a unified transport system designed to allow rapid movement of cane and materials, with


sufficient receiving and loading points, and having adequate carrying capacity. Main drainage may have to be supplemented by excavating new cuts, and altering existing ones. Roadways leading to loading points will need attention—old ones being consolidated and improved, and new ones constructed where needed. These major matters, railway, roads and drainage, should, with the erection of the new factory and all other works connected with it, have first priority. In the meantime, the old individual plantations could, and most likely would have to, continue operating more or less on their former lines, but with unified management, until the new central was ready to process the cane. Although by this time the transport system should come into operation, little if any of the minor works would be in their final and completed form, while much detailed work of other kinds would remain to be dealt with. Omitting further consideration of the centralization of cane processing, barely mentioned here to complete the outline of the picture, the work of replanning and consolidating a group of small estates requires great care and skill. Its execution must progress in the first year with little or no interference with production and thereafter it should lead under favourable conditions to yearly increases in output until maximum productivity is attained. For these, and numerous other but. minor reasons, several years continuous effort is needed to achieve success. Rarely did former planters have levels determined by instrument. Such work is, however, essential, though it offers difficulties in land which is under crop. Thus the determination of contours and slopes can only be carried on when fields have been reaped, so that it has to be conducted piecemeal in the case of land already planted in cane. This fact alone delays the completion of drainage systems for plantation groups such as those under discussion.

Human Relations Perhaps the material part of such a project—the new works,

reconstruction of old ones and so on—is the least difficult. Human relations become strained, particularly with older men who have been for many years associated with outmoded operating systems, and both open and veiled resistance to the introduction of new methods, new machines, new management, and indeed to the


complete change of system, is encountered. Labour, both skilled and unskilled react in a similar manner but to an increased degree. The former close-knit association of a comparatively small number of operatives of all grades with a personal owner who knew them all by name and entered into their interests, becomes replaced by an impersonal employer represented by a manager or other controlling officer who is most likely a stranger to all, or most of them, and in any event is far too busy to be able to attend personally to their complaints, questions and representations, however willing and sympathetic he might be. This aspect of planning and reconstruction calls for great patience and consideration by all executive staff, combined with tact, firmness and determination. The establishment of good relations with staff and workpeople in the lower ranks is vital to speed and success.

Field Planning The desirability of having fields of uniform size, so far as con

ditions permit, has been mentioned, but in practice it will be found that the subdivisional layout influenced as it is by contours, railway, roads and drains, will not entirely conform to a chequer-board pattern. Underground and surface water movement towards the drainage system affect the matter, as also does the method of irrigation where that is practised. Protection against erosion on the one hand and water logging on the other has to be provided. On almost level land the direction of field drains, planting and irrigation furrows will be across the contours. As the slope increases, the angle made by furrows with the contour lines will decrease, until in steep land it becomes very acute. In rolling and hilly land planting lines and field drains must be in the direction of contours so that the straight rows characteristic of flat land are not possible. These factors are related to crop planning. A complete crop cycle of plants and ratoons occupies a period of years depending upon the number of successive ratoons profitably grown. It is economical to have consolidated areas each consisting of a number of fields in the same stage of a crop cycle at the same time. In this way the equipment and men required for work on the land are concentrated with advantageous results in many ways. Thus the field planning should provide for organized production on these lines, with long tractor-implement runs from


field to field through intervals between fields. The size of such blocks of fields will largely be determined by drainage and irrigation systems. Each field group of this type should form a definite subdivision so that when the time arrives for the operations of replanting, the isolation of irrigation will not affect other parts of the plantation, and no interference with the general drainage can occur. Individual field drainage may be temporarily checked or altered, but is restored as quickly as possible.

Importance of Basic Planning Discussion of this subject is obviously limited to the more

important matters of plantation and field planning, which have been treated broadly. Numerous points of detail arise in any particular scheme, which can only be dealt with on the spot. The principles outlined are somewhat like the structure of a building, which is designed to fulfil a definite purpose. The purpose influences the external and internal finish, and the furnishings provide for the achievement of that purpose. The structure is costly and difficult to alter once it is erected. Finish and fittings can be cheaply changed to meet new circumstances. This analogy may serve to emphasize the wisdom of using great care in the basic planning of a sugar-cane plantation, whether it be a new project or the re-designing of an existing one.

BUILDINGS

General Considerations The conduct of operations is influenced by the location, design

and construction of essential farm buildings. In discussing these, any matters related to the provision of housing for staff and work people are excluded. The extent and nature of building requirements are influenced by the scale of cane production, and the methods employed. When working animals are used the general arrangements and types of structure needed will differ from those associated with complete mechanization. The subject is closely related to time and cost factors connected with the conduct of normal plantation work, more particularly the movement of men, equipment, and materials to and from the fields, and the protection of tractors, vehicles, implements; and general supplies.

A large plantation with a number of subdivisions will need


buildings for each section or group of farms operated as a s ing le unit comprising 1,000 acres or more of land. With smaller es ta tes less than about 1,200 acres in extent, it will usually be found c o n venient to centralize farm buildings. Exceptions to both cases are the pens and other structures needed for livestock when working animals are used.

Location In the first instance the general requirements for a fully

mechanized estate may be considered. The need for protection and effective maintenance of all farm machinery, referred to in Chapter 14, is again emphasized. At the same time the movement of such equipment when not actually at work on the land, s h o u l d be restricted to a minimum. The siting of farm buildings s h o u l d therefore be to a large extent decided with this factor in m i n d . Other points affecting the choice of location are drainage, ease of access with respect to the area served by the buildings, exposure and security. Water, and if possible electric power should be available for all needs. Weather exercises a marked influence on t h e selection and layout of a site for such structures, as well as u p o n the design for each building and the type of construction. In places where heavy rainfall, high winds, and cyclonic storms are experienced, the protection afforded by natural features should be taken into account, and arrangements made so that under n o r m a l conditions buildings can be approached from the leeward s i d e .

Protection It is an advantage in most countries to enclose the area by a

secure fence with a minimum of gated entrances and exits k e p t under constant control by responsible gate-keepers. Sui table material is 2-in. mesh No. 6 American Standard Wire G a u g e chain link fencing of copper bearing steel, galvanized af ter weaving, the top and bottom having a twisted and barbed f inish. The fence would usually be 6 or 8 ft. high, with turn in brackets , carrying three strands of barbed wire, fitted to all posts.

Storm Resistance Structures must be of ample reserve strength to withstand t h e

velocity pressure of high winds, which is the increase b r o u g h t about by air movement over the normal pressure at sea level at


15 ° C. of 14.7 p.s.i. The American Civil Engineers Handbook gives the figures quoted below for wind speed ranging from 10 to 120 m. per hr. The direct normal wind pressure is calculated by the U.S. Signal Service formula (1913) P = .004V2 where P = the increase in pressure in lb. per sq. ft. caused by a wind of velocity V miles per hour. This gives results about 50% higher, but for practical purposes it is wise to use them.

Velocity Pressure Caused by Wind

Local considerations of supply and cost will largely determine the construction materials to be used, which in turn will have some influence on design. Buildings should be erected to plan and specification, with adequate provision for future needs either by increased floor area in the original construction, or by extensions built as required in conformity with the basic plans; Should there be any likelihood of the necessity arising to move all or any of the structures to another site, steel frame construction is desirable, using sheeting of corrugated iron or asbestos cement for roofs and walls. This type of building is rapidly erected and can without difficulty be made of ample strength to withstand cyclonic and other violent storms. Where these are liable to occur, the


safety factor for any form of permanent construction must provide sufficient margin for veering winds of maximum force. At the same time the method of securing the roofing material and the protection of all openings must receive special attention.

When asbestos cement sheeting is used for sides and roofs of such buildings, it is essential to combine firm attachment to the framework with provision for the differing degree of expansion and contraction of the steel work and the sheeting. Cases have occurred of the rupture of heavy grade sheeting bolted directly to steel work. The greater expansibility of the steel imposed such strain that the sheeting was torn apart, and the rents in the channels of the corrugations made it necessary to replace a high proportion of the material. The trouble can be corrected by the use of distance pieces of wood or other suitable material which will allow for lateral movement of the steel and sheeting while giving the necessary firmness of fixing. Another method is to use wooden purlins to carry the sheeting. C.G.I. Sheeting is sufficiently flexible to adjust itself readily to the effects of temperature, though these become rather annoying in some cases because of the noise generated by the deformation of the metal when expanding or contracting.

Fire Protection Fire protection is a major consideration. Though steel frame

buildings with C.G.I, or asbestos cement sheeting are fire-proof, their contents may and probably will be inflammable to a greater or less extent. Intervals between buildings should therefore conform to fire insurance conditions, and if they are near to the cane fields the area in which they are situated should be sufficiently large to avoid any risk of a cane fire spreading to them or their contents.

Precautions against fire are well defined in regard to storage installations for liquid fuels including crude oil, distillates, and light petroleums. These often form part of the essential services, and for ease of control and convenience are usually sited in the same area as other central estate buildings. They must be well isolated from points which are capable of generating fires, and attention paid to ventilation and air drainage to prevent the accumulation of explosive gases.

PLANTATION AND FIELD PLANNING 129.

Dust Avoidance Though dusty conditions seem to be normally associated with

roads, tracks and other exposed places during dry weather, and particularly in the reaping season when traffic is most dense, the areas containing buildings should be as free as possible from the dust nuisance. Apart from the health and comfort of various classes of operatives, among whom are included the office staff, the effect of dust upon equipment and machinery of all kinds should be reduced to a minimum to avoid damage and unnecessary wear. Small machinery, such as typewriters and calculating machines at one end of the scale, and tractors and heavy implements at the other, suffer reduction of useful life by the effects of dust and fine grit blown about from the surface of earth roads whether under traffic movement or not. The central buildings area, in which are concentrated the offices, stores, workshops, implement sheds and other structures should have roads with dust-proof surfaces. Grassed verges and lawns will minimize the generation of dust in open spaces, and the cost of their maintenance will be saved from the increased efficiency of staff, the longer life of equipment, and the lower costs of interior as well as exterior maintenance of the buildings. Sanitation services must receive careful attention from the outset.

Central Office The heart of the buildings area will be the central office, pre

ferably a two-story structure with the administration section on the upper floor. A site to the windward of workshops, implement sheds and other buildings is desirable. The design should incorporate a fire-proof chamber for the safe keeping of important documents, and records, as well as a built-in safe for money and important account books in daily use. Ample space is needed for filing cabinets, maps and plans, which tend to increase in quantity with time, and if not provided for in the original design will encroach on floor and wall area to such an extent as to interfere with convenient working. There should be one room of sufficient size for staff meetings and similar purposes. Consideration should be given to the provision of a kitchen, pantry and dining-room, either as a part of the office building or as a separate establishment, if meals and light refreshments are taken by staff without going to


their places of residence during the working day. When these facilities are available, the entertaining of visitors is made easier.

A motor shed and parking space for staff and visitors will be required. It should be conveniently near to the main entrance of the building, where a forte cochere will prove a useful feature in wet weather. If possible the approach to the office block should be clear of any main road to other buildings to minimize the disturbance caused by heavy traffic. At the same time there should be ease of access to all other parts of the central buildings area.

Workshop and Implement Sheds The accommodation provided for workshops and implement

sheds, will be largely determined by the location of the plantation as a whole with relation to centralized repair and maintenance facilities serving a number of estates, and to the extent of mechanization of field operations. An organization of the size under discussion will require well equipped workshops capable of carrying out major repairs and of providing all the shop servicing needed for tractors, vehicles and implements. The general arrangements should be planned for the most efficient working, with ample floor space in the repair shops. Open-sided sheds for tractors, vehicles and implements with adequate capacity for the shelter of all such equipment when it is sent in for repair and overhaul are needed. All these buildings should have spacious yards or open areas to allow free movement without congestion. When possible the design should provide for ingress on one side and egress on the other. This will save time and reduce damage, which occurs to a much greater extent when machinery is moved in reverse.

On a large estate of the type under discussion, tractor, vehicle and implement accommodation will be required for each main subdivision, but provision for repairs should in general be limited to comparatively minor matters which can be readily dealt with by a mobile unit such as that described on p. 294, but which cannot conveniently be carried out in the field. An area office will also be needed. The location and site plan should conform to the general principles applying to the central office area. It is essential that the central and all subdivisional building areas should be served by both the railway and road systems of the estate. Telephone communications between all principal buildings and offices


through a plantation exchange, preferably automatic, with connection to all other important points including the residences of the staff, and to external public lines if they exist, should be provided.

Effect of Livestock on Planning Estate planning when large numbers of livestock are used displays

great differences from that associated with extensive or complete mechanization. It would have been chronologically correct to discuss this subject before dealing with the general requirements of a large estate using few, if any, working animals. Most sugarcane plantations have been originally established for operation with human and animal power, and as is described in Chapter 14, have adopted mechanical power for various economic reasons. In places where this has occurred to a maximum extent the better land formerly needed for pastures and pens has been planted with cane, and a general redesigning of fields has taken place. There are, however, many plantations which continue to use some livestock for field work and haulage, though there is an increasing tendency towards mechanization. Steers, mules and water-buffalo are used as working animals and horses and mules for riding. Donkeys are useful on very small farms but are merely mentioned in passing.

In general, smaller fields, and consequently more traces, intervals and roads, are a feature of the use of livestock. Fenced paddocks, pens and pastures are needed, taking up a total area equivalent to one acre or more of land for each animal. The location of these must provide for shelter, drainage, and water. Working steers are kept in the open, but mules and horses need stables. Water-buffalo flourish during rest periods in and near streams. The maintenance of a breeding herd to keep up the supply of working steers involves additional provision of enclosed areas, located on a separate part of the estate.

The accommodation for the feeding and enclosure of working animals must be so situated that they need to travel as short a distance as possible to the point where they are actually put to work. Horses and mules in particular need what may be called " special feeding" as compared with working steers, which flourish on the trash and tops in the field during crop operations, and subsist on pasturage, usually on poor land, when reaping is


finished. During the out-of-crop period they are still needed for field work, and as a general rule their usually poor efficiency as power units falls off, while pasturage or other adequate feeding must be provided for them.

Animals v. Machines The older generation of cane planter views with disfavour the

displacement of livestock by machines, and finds many reasons satisfying to himself, though unconvincing to unprejudiced observers, for the superiority of animals over tractors. The value of farmyard manure as a fertilizer for the cane fields is strongly asserted, and the ability of animals to work under field conditions which are unsuitable for tractors becomes exaggerated. A more important point in their favour is the fact that they live on the produce of the farm, while steers need little protection or attention when not at work if confined in fenced enclosures, so long as feed and water are available for them.

It has been shown that working livestock on the cane plantation may be regarded as an intermediate phase between the manual workers of the very early stages of the industry and the modern machine age. Even now the manual worker has not been entirely replaced, nor is the animal likely to disappear completely as a part of the power supply for cane production. Traditional practice may survive longer in the older cane-growing countries, where as in India and the West Indies, men and animals still perform a high proportion of the work, particularly on small farms. These methods are associated with limited areas under cane and comparatively small annual production, under conditions where land is available for pasturage, and cane growing is associated with cattle rearing. In some places the cattle industry has been developed largely because of the demand for working animals by the cane industry and other farming activities. The decreasing need for steers has caused breeders to turn to the raising of beef and dairy stock, for which there is a rapidly expanding market.

The greatly increased production of cane sugar over the past 30 years could not possibly have been achieved by the sole use of manual labour and working animals for farm operations including haulage. Reversion to former methods—those used in what may be termed the pre-mechanization period—would in the British


West Indies, for example, bring about a severe limitation of the area of land devoted to sugar-cane even if adequate manual and animal power were available. Mechanization is by no means the only contributory factor to the increased crops, but the advantages of improved varieties, and advances in field and factory methods could not have been so great without it.

The two phases of the cane cycle which require the maximum effort are land preparation for planting and haulage of the reaped cane. To a great extent these take place concurrently, particularly where cane is grown under natural rainfall, and require 1 working steer to each 3 acres of land devoted to cane cultivation. Thus a farm of 1,000 acres, with 750 acres reaped, and 250 acres replanted yearly will require 320 animals in condition fit to work, and an additional 130 to allow for young animals in training, sickness, injury and age. The working life of hardy steers is 7 years, so that the annual replacement should be 50 animals. Aged animals are " fattened "—usually rested in rather indifferent pastures for a few weeks—to get them into suitable condition for sale to butchers, the prices realized being considerably lower than the cost of 2-year-old young steers. The approximate position in any year near the end of the reaping season would be :—

320 fit working animals 50 young steers in training 45 aged to be fattened and sold 32 sick and injured

Losses by death through injury and disease are estimated at 5, thus accounting for the reduction to 45 animals available for sale. Allowing 1¼ acres per head for pastures, paddocks and similar enclosures, an additional area equivalent to more than 50% of that used for cane will be required, divided into fields of suitable size, most if not all of which must be fenced.

The urge for rapidity of movement which has characterized all industrial development has affected the sugar-cane planter, and has caused the slow moving steer to become outmoded on all but the small cane farms. Among other economic factors affecting the place of livestock in sugar-cane agriculture is the great increase in


world population and the consequent increased demand for food, particularly proteins. In the past the combination of crop pro-Suction with farm livestock represented what was accepted as good farming. Animal power and labour were low in cost, and readily available. In fact, supply was often in excess of demand. At the same time mechanical power was cumbersome, expensive in capital cost, and only suited to plantations of extensive area having suitable types of soil. Farmyard manure was regarded as the only satisfactory fertilizer for the fields, and the use of artificials was reluctantly adopted to supplement them. Concurrently with the increasing demand for food, the developments of agricultural mechanization, and the recognition of the value of chemical or artificial manures, the practice of more efficient crop production methods and a great advance in the outlook of the planter have developed. The sugar-cane industry has shared this progress with other forms of agricultural effort. Land formerly used for the pasturing of working livestock is now largely devoted to sugarcane, foodstuffs for human consumption, and cattle rearing for beef production and dairy purposes. The older practices, suited as they were to conditions as they formerly existed, can no longer hold their place if the growing population of the world, which has more than quadrupled since the early days of cane sugar growing in the British Colonies, and now exceeds 2,200 million,* is to be adequately fed.

* Nature, Vol. 65, N o . 4196.

F I G . I6.—Vertical photograph of a sugar estate in Jamaica at a scale of 1/10,000. In this photograph, some of the fields are seen to have been harvested.

[Courtesy of Hunting Aerosurveys Ltd.

FIG. I 7.—Part of a map of a sugar estate in Jamaica. Plotted at a scale of 1/4,800, with the areas of individual fields shown in acres.

[Courtesy of Hunting Aerosurvey.. Lid.

CHAPTER 9

THE PLANTING AND CULTURE OF THE CANE

Crop Planning It will be realized from the chapters dealing with soils, drainage

and irrigation, that the methods of land preparation, planting and culture of the sugar-cane must be adapted to the conditions which the plant will encounter during its growth cycle. Soil and climate determine the choice of varieties, a factor which may also be influenced by the time taken to reach maturity. Crop planning is an important detail in plantation work. It is conditioned by the period during which mature cane is accepted by the mill, so that the planter's object should be so to plan his production that cane in prime condition is ready for cutting throughout the milling season in uniform weekly, or preferably daily quantities. These are the principal considerations which affect the annual planting programme.

A Typical Crop Cycle An established sugar-cane plantation a few weeks before the

reaping season will be subdivided into groups of fields somewhat in the following manner, with variations in practice caused by local conditions :—

(a) plant cane (i) young (ii) approaching maturity

(b) first ratoon cane (c) second ratoon cane (d) fallow

Assuming that no older ratoons are grown, the mid-reaping season will present this picture :—

(a) plant cane (i) young (for next crop) (ii) mature being reaped and approaching

maturity (b) first ratoons : being reaped (c) second ratoons : about to be reaped (d) fallow, and newly planted

K 135


From then to the end of " crop," land devoted to second ratoons will be reaped and " thrown out," that is, made available for replanting. The crop cycle in this case is a plant crop and two ratoons, or three crops in all between successive replantings. It usually involves the preparation and planting of the equivalent of one quarter of the total cane area each year to maintain the same average level of production. Should additional land be available, part of this may be used, leaving a similar area of the thrown out cane land in fallow. A common practice is to leave the trash on the land for a few weeks after reaping the cane. During this time it will begin to rot, so that a heavy disc plough can be put over it. This rough ploughing, which partially destroys the old cane stumps, is followed either by the growing of a leguminous crop as a green manure, or by a short period of fallowing, until just before the planting season, when the real preparatory work on the land is carried out. A variation of this method is to remove the trash to the side of the field, returning it at a later stage for use as a mulch, or applying it to adjoining fields of young plant cane. In this way the land surface becomes more suitable for ploughing. The movement of the trash is a rather expensive operation, and this consideration combined with the need for speedy preparation for the succeeding crop often decides the planter to burn off the trash. It has been shown that the nature of the work to be done is related to the type of soil. The mode of working varies widely. Apart from very small individual cultivations not exceeding a few acres in extent, such as are found in peasant communities, the manual working of former times has been superseded by animal-drawn implements or complete mechanization, with an increase in the depth to which soils can be effectively ploughed, and a great improvement in the quality of the work performed.

Ploughing Ploughing is done to a depth of about 12 to 14 in., at a time when

the soil is moist but not too wet, and can be turned easily. It is desirable that dry conditions should prevail so that work may be continued quickly and the weathering of the land proceed rapidly. Thus in areas where the cane is grown under natural rainfall most of such work will be undertaken during periods when minimum rainfall is expected, no opportunity being lost of getting

THE PLANTING AND CULTURE OF THE CANE 137

something done whenever the land is in fit condition to be worked. Equipment should be adequate to provide what may be termed a reserve of ploughing capacity as it is imperative that ploughing, and indeed all other essential land operations should be conducted and completed at the proper season when the major controlling factor is weather. Under conditions of irrigation, more latitude is allowable, and the strict seasonal timing which is so important otherwise, can be relaxed.

The Cambered Bed System Heavy rainfall imposes the necessity for field drainage, and the

use of the cambered bed system or other methods of quickly disposing of surplus water, as described in Chapter 5. In these circumstances, land preparation is carried out in a direction parallel to the field drains, so as to disturb them as little as possible. The method of combining operations on several fields at the same time so as to get long straight runs with the minimum number of headland turns causes damage to head drains at the sides of fields, though this can be reduced when track tractors with lifting gear for implements are used. It may in some cases be worth while to use portable bridges to pass such equipment over head drains.

The ploughed land is left to weather for a time, and sub-soiling is then done to a depth of 21 in. or more in land where it is required. To be successful this operation requires comparatively dry soil conditions, which are assisted by the length of exposure of the ploughed soil. In wet climates such favourable conditions do not always occur, so that a decision to omit this treatment may be necessary, as it is waste of effort and damaging to the land to perform subsoil ploughing when the soil is too wet. Waiting for the necessary dry spell may entail delay in planting and upset the timing cycle with resulting adverse effects on the crop.

Drainage which may have been interfered with during these stages must be restored quickly, and this work immediately succeeds subsoil ploughing, being combined with that of the final stage of bed formation. The beds now appear with their centres about 12 to 15 in. above the drain edges on either side, the field trenches complete and unimpeded, leading to the head drain at the side of each field, all being ready for the planting operations.


If planting is to be done by hand, furrows are cut in the cambered beds parallel to the field trenches, with distances between centres ranging from 4 ft. 6 in. to 6 ft. in accordance with the practice of the plantation.

a b

FIG. 18.—Cambered beds (sectional view), a. After formation and before furrowing, b. Furrowed, ready for planting, c. Position of cane rows. The spacing between rows in 22-ft. beds is usually 4 ft. 6 in. Ideally it should be possible to have five rows to each bed, but the outer rows are then too near to

the drain edge. Cane rows in 24-ft. beds are generally 6 ft. apart.

P l a n t M a t e r i a l The selection of plant material is of high importance, and well

repays the most careful attention. The cane used for planting should preferably be well grown plants about 10 to 12 months old. In plantations where diseases and insect pests capable of causing serious damage are present, which can be transmitted to the new plants by the seed pieces, more careful inspection is necessary. It is excellent practice to establish a special cane nursery in each section of a plantation, of sufficient size to provide seed pieces for the area of land to be planted in that section. Each nursery contains the varieties best suited to the fields which are to be planted, and receives special attention with the object of producing a vigorous growth of cane free from pests and diseases.

Where this procedure is not adopted, planting material is taken from fields of growing cane in the desired condition. Any planting done during the period of " crop " is usually with " cabbage " tops—the upper immature portion of the cane which is cut off in the field by the reaping gangs.

Planting Hand planting methods vary considerably. Traditional in the

West Indies, and continued until now, is what may be termed


dibbling. Pieces are cut from unripe whole canes, each having two or three nodes. These are the cane setts or seed pieces, and are usually prepared by women working on the interval at the side of a field to be planted. Alternatively, this work may be done at some central point from which the setts are distributed to the fields. The cane is chopped on a wood block, using a cutlass or machete. The operation of planting is performed by making a hole at an angle of about 300 to the vertical using a tool like a miniature pick, into which the cane sett is pushed with eye tips upwards, the soil being consolidated round the sett by the worker's toes. The setts are placed on alternate sides near the bottom of the furrow, with the upper ends just projecting above the surface. The density of planting varies from about 2,000 to as many as 10,000 setts per acre.

The canes may be planted whole, or in sections, in which cases they are laid at the bottom of the furrow and lightly covered with earth from the intervening ridges, which is pressed down.

Planting in Florida Everglades In Florida very great care is taken to ensure that sound seed only

is used. The seed canes are taken from selected fields, stripped of trash and cut into three or four-eye setts which are rigidly inspected. Furrows 4 to 8 in. deep are cut 4 ft. apart by a tractor-drawn 3-row furrower, parallel to field ditches. The seed cane is carried to the fields by tractor-drawn wagons and is planted by hand in a continuous line with the seed pieces overlapping each other about one-third of their length. Soil improvers and fertilizers are mechanically applied at the same time, by a machine which drops the material, closes the furrow, and packs the soil at the rate of 5½ or more acres an hour. A complete planting unit of 180 men, 9 tractors, of which 1 performs the work of fertilizing and covering, and 24, 5-ton crawler cane wagons, complete 50 acres in 9 hrs. from cutting the seed cane to covering.

Depth of Planting An essential requirement for successful germination is a well-

prepared seed bed which is moist at the time the setts are put in. The term depth of planting is rather misleading as it really applies to the distance below the surface of the land before the furrows


are made at which the plants are placed. This may be from 6 to 8 in., though lower "depths" are sometimes used. The soil below the level of planting should also be in good tilth. The setts recumbent in the deep furrow are covered with a layer of soil the thickness of which ranges up to 4 in. under very dry conditions ; but should be not more than 1 to 2 in. if the soil is moist and other factors are favourable to growth. Heat as well as moisture assists germination. Cool dry weather may retard it so that the setts remain dormant for some weeks, but it has been found that a thick soil cover does not improve germination, the important factor being the depth of planting below the land surface.

Fungicidal Treatment When delayed germination may occur it is necessary to use

fungicides to prevent the destruction of the setts. Organo-mercurial compounds have been proved to be best for this purpose, particularly " Aretan " used in solution in water at a strength of 0.5%. The cut ends of the cane pieces are dipped into the solution, and planted immediately. This treatment not only checks losses through delayed growth, but improves germination, and increases yield.

Some Causes of Planting Failures Much unnecessary loss of planting material and a great deal of

additional expense in planting are incurred by careless work and neglect of what are now regarded as basic precautions. Careful preparation of the seed bed and attention to drainage and other crop protection arrangements are essential, but often good work of that description is sacrificed because of poor quality planting material. Many planters are still reluctant to cut back vigorously growing plant cane for use as seed, and planting failures traceable to the use of old ratoons for this purpose still occur. The seed canes should be cut into seed pieces and planted, or planted whole, as quickly as possible, the greatest care being taken to avoid damage to the nodes and particularly the eyes. Replacement of setts which have failed to grow, known as " supplying " is an expensive operation, which should rarely be necessary. When it has to be done, the setts which have failed to grow should be dug up and examined in an endeavour to trace the cause.


Fertilizing The application of artificial fertilizers can be made at the same

time as planting when the cane is laid in furrows. Otherwise it becomes a distinct operation, except when mechanical methods are used, usually carried out in one or two stages. Investigations have shown that manuring can be done at or immediately after the time of planting with no detectable difference in effect on the crop, and that it does not matter whether the total amount is applied in one or more doses. This stage of crop production is beset in many places by the persistence of traditional custom, and like others is often difficult to modify (Fig. 19). Mechanical planting is replacing manual methods, the three operations of opening the furrow, planting the cane and applying fertilizer being conducted simultaneously. A tractor hauled, two-row mechanical planter will complete 1 acre in 1 hr. if properly supplied with cane setts and fertilizer.

Almost level land under very high rainfall with a high water-table requires more intensive drainage than is provided by the cambered bed system. Field furrows are deeper and the intervening ridges higher, the cane setts being planted on the top of the ridges—see p. 73. On the other hand, flat free draining soils under irrigation need fewer surface drains, and all preparation and planting work can be conducted more easily than in the cases just described. In irrigated land, water is applied to the furrows a day or so before planting. If mechanical planting is done, the land can be previously wetted, or water put on immediately after planting, a light application only being made.

Considerations Affecting Time of Planting The time of planting is important in relation to expected weather

conditions in the absence of irrigation ; to the variety being grown, which is also influenced by other considerations ; and to the proposed age of the crop at reaping. The period during which planting may be done under natural rainfall conditions is normally limited in the tropics to a few weeks in the spring and autumn (or fall), whereas with irrigation it may continue for a total of 6 months or more each year. This is one of the reasons for the careful timing previously referred to in respect of the former conditions, but even this will not avoid the adverse effects on germina-


tion and growth caused by protracted dry weather after planting, though it will mitigate them.

Variety Selection It will be realized from the discussion on varietal behaviour in

Chapter 7 that some canes mature within a definite period and remain in prime condition for many weeks, while others may ripen earlier or later and deteriorate quickly after ripening. The planter therefore selects the varieties for planting with these factors in mind, in order, as far as possible, to have ripe cane for cutting throughout the milling period. The area of each of a number of varieties is also partially determined by the characteristics of the ratoon crops. On a large estate the inter-relation of these factors requires careful study when the annual planting programme is being considered.

D e n s i t y o f P l a n t i n g The term " density of planting " is sometimes used to denote

the number of setts or seed pieces planted per acre. It applies more particularly when the manual method of dibbled planting is practised. The quantity of young cane required per acre for planting depends upon the planting density, which is determined by the distance between row centres, and the spacing of the setts in the rows. Investigations have shown that within limits variations in these distances do not appreciably affect cane yields. Thus, it does not matter from the yield point of view whether rows are 4 ft. 6 in. or more apart up to 6 ft., or whether the number of setts planted is 4,000 or more up to 10,000 per acre. Practical considerations determine row spacing and the number of seed pieces to be planted. In non-irrigated land, where wet conditions prevail for long periods, making inter-row work difficult .and sometimes impossible, rows 4 ft. 6 in. apart with about 8,000 setts to an acre have been found most suitable. With normal germination and growth, a canopy is formed which covers the space between the rows in about 3 months. After that stage has been reached no further inter-row work is necessary—nor indeed is it practicable. Wider spacing encourages greater weed growth, needing more work and expense to control it, because of the longer time required for the cane to " cover down " the inter-row space.


It is important to keep in mind the limitations imposed on mechanical, animal or manual work in the cane fields in regions of high rainfall, and the positive danger of damaging surface tilth by movement over the soil when the land is wet. The same considerations of inter-row distances apply when what is called continuous planting is done, by laying the whole, or portions of the cane in the furrow. With this method practically every eye germinates, while with dibbled planting the topmost eye grows and possibly though not always the second. When regular well-defined dry seasons normally occur in areas with ample rainfall, more inter-row work with machines is possible, and rows are then 5 ft. 6 in. to 6 ft. apart.

P a c k i n g o f S o i l b y M a n u a l P l a n t i n g

Manual planting methods involve much trampling of the prepared soil by the labourers, which causes some packing of the surface layer. Often when the planting has been completed, well-defined tracks will remain between the rows until the first weeding and inter-row cultivation, which is done when the cane sprouts are showing above the ground. Mechanical planting is free from that disadvantage.

Weeding The control and suppression of weeds is effected in various

ways, but methods involving the use of hoes, and animal or tractor-hauled implements of various kinds are rapidly being replaced by the application of chemical sprays. Customs persist long after they are outmoded, though there are sound reasons for continuing some of the established practices of weed control in association with the new chemical methods, particularly in irrigated land where surface application of water is made. At the time of planting the cane the land should be free from growing weeds, but though this may appear to be so, they will soon become apparent in most soils. The very conditions which are desirable for the rapid germination and subsequent development of the cane are those which assist weed growth. The general practice has been to put light implements through the land to disturb the surface soil and so to destroy the growing weeds, while at the same time the ridge or bank between the cane rows is broken and


the earth from it moved partially into the furrows at the base of the young canes (Fig. 20). It is undesirable to fill in the cane furrow until the cane has produced its secondary shoots forming a stool. Unless the row is kept open, with a light layer only of soil, these secondary shoots will appear at too high a level. Thus the inter-row weeding when furrow planting is practised should not be allowed to fill in the furrow until the young plants have stooled. The line weeding, or row weeding, can be done with a light mule-drawn spring-tined implement which has small discs set to throw the earth away from the row. This is only possible when the plants are very young. Later stages of inter-row weeding and surface cultivation fill in the cane furrows after the plants have stooled and finally leave the land surface level. The intervals between these operations are mainly governed by the weather and state of the land. Occasionally it is impossible to work so that weeds grow profusely and become more difficult to keep down. This cultivation by animal and tractor-drawn implements, does in favourable conditions maintain the inter-row spaces free from weeds and in good surface tilth, but weeds in the cane rows, though partly covered by the soil moved from the banks, are not effectively dealt with, so that some hand-weeding may be necessary. Under favourable conditions, and in contrast to the old manual customs still practised, the rotary hoe is effectively used for weeding and cultivation.

Apart from the effects on weed growth and the maintenance of surface tilth, inter-row cultivation helps to conserve moisture in the soil, a factor of great importance especially where rainfall is deficient (Fig. 21). In some places with low rainfall and no irrigation, the inter-row spaces are mulched with grass, which checks evaporation from the surface of the soil and assists in suppressing weeds. It has been proved that an increase in cane yield of 5 % is brought about in this manner.

Row Spacing in Irrigated Land Under conditions of irrigation, the space between the rows

must be sufficient to allow the work of watering to proceed easily so that a minimum of 5 ft. is customary, which may in special circumstances be increased to a maximum of 6 ft. Chapter 13 deals in more detail with the principles and methods of applying


water. It should, however, be emphasized in connection with present considerations that the surface cultivation necessary after furrow irrigation effectively controls weeds in the inter-row spaces, still leaving the line weeding problem to be dealt with.

Chemical Weed Control

The development of chemical methods for the destruction of weeds has provided the sugar-cane planter with a new, effective and easily applied remedy. Having determined by investigation the best mixture and dosage to use against the weed growth prevalent in the cane fields of a particular area, a choice of methods is available to meet the prevailing conditions. The application of weedicide at the time of planting will so control the germination of weeds while not adversely affecting the cane, that no further weed treatment is needed for several weeks. Under natural rainfall conditions the land is left undisturbed until a second weedicide spraying is needed, and again after that up to the time of the third application, which may or may not be required. It has been found in some places that portable pressure sprayers are the most convenient to use, though tractor-drawn and powered sprayers are also employed.

In irrigated land the pre-emergent weedicide treatment can also be given, but with surface watering, the inter-row cultivation work is still necessary. A convenient procedure therefore is to use the spray method for the second and later line weedings leaving the cultivation implements to cope with any weed growth between the rows. Low volume spray material and equipment are desirable to avoid the use of large quantities of water and its movement over the land in the sprayers. In all operations of chemical weed control there should be the least possible movement of men and machines over the planted land, to reduce damage to surface tilth and avoid the need for inter-row cultivation work, except as required in the special cases mentioned.

Irrigation : Trashing

From the cultural aspect, little remains to be done until the cane has been reaped, except in irrigated plantations where regular watering is carried on in accordance with weather and

146 AGRICULTURE OP THE SUGAR-CANE

crop requirements until about 6 weeks before harvesting. An operation known as "trashing" was sometimes carried out, though like many others conducted extensively when labour was comparatively cheap and plentiful, it has apparently almost died out. It consisted in a simple removal of loosely adhering dead or dying cane leaves from the cane as it approached maturity. Workers using sticks or the backs of cutlasses walked between the rows stripping these leaves and leaving the stalks practically bare except at the top where the tufts of green leaves remained. It could only be effectively performed with free trashing varieties of cane—those from which the older leaves became easily separated. The operation was said to stimulate ripening, but this does not appear to have been scientifically confirmed.

Ratoons After the plant cane has been reaped and carried away cultural

work for the ratoon crop begins. The surface of the land is covered with a mat of cane trash, so that the rows of cane roots can hardly be distinguished, if indeed they can be seen at all. In irrigated land, which normally gives heavier yields of cane, the residual trash is very dense. Before anything can be done to assist the new growth, whether by surface watering, application of fertilizer, or tillage, the trash must be moved from the rows, or cut through mechanically. A long established practice still widely used is to rake the trash away from the cane rows and place it between them in such a manner that two adjoining rows and the intervening space are bared. The trash is thus deposited in the alternate inter-row spaces. In these conditions the three operations mentioned can be readily conducted in the bare spaces, every row thus being approachable from one side. After a time the trash was thrown into the formerly bare space, leaving previously occupied inter-row spaces free. Under present circumstances this work has become too costly. Whether it was ever really worth while is doubtful. A simpler and less expensive method of exposing the cane rows is to pull or rake away the trash from the lines of roots, leaving it between them. Fertilizer can then be applied easily, but surface watering needs furrows, and complete removal of the trash from a sufficient portion of the inter-row space becomes necessary, or an implement of the type described on p. 287 must


be used. A trash mover has been evolved in Puerto Rico. Attached to an Oliver-Cletrac tractor it " rows " the trash at the rate of 1 to ½ acres an hour.

The rows of cane become visible through the mat of trash as the sprouts emerge, and indicate where fertilizer should be dropped. The trash can be left undisturbed, when it acts as a mulch, suppresses weed growth, and rots in a few weeks of wet weather. With natural rainfall, therefore, no work need be done for ratoons other than applying fertilizer.

The Field Trash Problem The undesirable practice of burning before reaping is still con

tinued though to a decreasing extent. This destroys most of the trash, so that the land is left in a condition which enables cultivation, furrowing for irrigation when required, and other work to be carried on more easily. In many places the cane is reaped without being previously fired, but the trash is burnt on the ground immediately afterwards, more especially in irrigated areas using surface watering. An alternative method which appears to be promising is to cut through the trash near the rows of roots, at the same time preparing a furrow underneath it, and applying fertilizer. The very slow rotting which occurs under the dry weather conditions which prevail for most of the year in low rainfall irrigated areas is a disadvantage, as much of the trash persists on the ground until the reaping period. The heavy crops usually obtained under irrigated conditions produce correspondingly large amounts of trash which add to the difficulty.

Opinion differs on the merits of trash burning. No apparent harm either to the soil or the succeeding crop occurs. Weeds are provided with favourable conditions for growth, but watering and manuring are greatly facilitated. Much depends upon the general weather and other conditions, including labour. In wet weather the trash rots, and fair ratoon crops are grown with no attention, results being greatly improved by manuring even if the trash is not disturbed. Experimental work has been done to decide the relative advantage of various methods of dealing with this problem, but results are inconclusive and more work is required. Each plantation offers a local aspect of the question so that it is unlikely that a solution capable of general application will be found.


Preparing for the Next Plant Crop Procedure for succeeding ratoon crops follows the pattern for

first ratoons, with local variations influenced by prevailing conditions. After reaping the last ratoon of the cycle, the land undergoes treatment to prepare it for the succeeding plant crop. An important principle is to keep the land covered with trash or with some kind of growth, preferably of a useful nature, leaving it bare for the shortest possible time consistent with the normal and efficiently conducted operations of sugar-cane agriculture. Thus, after the last crop has been taken off, the land is covered with trash if burning before reaping has not been done, or if that practice is followed, what is practically a bare surface is left exposed. In the former case a little delay is allowable before proceeding with work, but in the latter it is advisable to start on the succeeding operations quickly. The procedure varies considerably, though the basic object remains the same—the preparation of a seed bed for the next plant crop.

" Spring " Planting If the land is to be got ready for the earliest possible planting,

trash will be burnt, and ploughing started immediately, the work proceeding as already described. This spring planting as it is termed in many countries, because it occurs during that season of the year, produces a crop ready for reaping in the succeeding season, at an age of about 12 months. Varietal selection is of obvious importance. The planting material used consists of a number of selected tops cut from cane being reaped for milling. There is thus no sacrifice of growing cane to provide seed.

Preparation for " Fall " Planting Thrown out land not required for planting until the fall of the

year may have a leguminous crop grown on it to be ploughed in later, or left in " bare " fallow for a time ranging from a few months to a year. The bare fallowing provides opportunities under wet conditions for heavy weed growth, which while keeping the soil covered, helps to maintain weed infestation in the land. The series of preparatory and planting operations continue in proper sequence, and another plant-ratoon cycle is begun.


Differences in Practice The description of planting and cultural practice outlined

applies more particularly to the British West Indies, though the basic principles apply generally, main apparent differences being in methods used. Local variations occur, for special reasons, while unique conditions such as those encountered in British Guiana are associated with unusual techniques.

Barbados The high density of population in Barbados, and the necessity

for producing locally grown foodstuffs have brought about a system of food cropping in association with the growing of sugarcane. It is a remarkable fact that this practice which on the face of it would appear likely to result in a limitation of cane growing has been accompanied by an actual increase in sugar production, and has exercised no adverse effect upon the acreage yields of cane and sugar.

Louisiana The bank and furrow system evolved in Louisiana and intro

duced in recent years in modified form to parts of the West Indies is in remarkable contrast to the furrow planting methods described. The cane is planted on the top of the bank and has to survive a cold winter period. A plant and one ratoon crop are grown, and after the latter has been reaped the banks are broken down and reformed in the former furrow. Corn and a cover crop are planted together in the early spring on the top of the beds, the corn being harvested in August after which the cover crop is turned in by a notched disc implement. In some cases the beds are again reversed. A shallow furrow is cut along the top of the bank, in which whole canes are laid overlapping one another to form a double continuous row. The rows are covered by the bed-forming disc implement to a depth of about 3 in., and a roller is used to consolidate the soil. The large quantity of seed cane, which amounts to 4,000 lb. per acre in some cases, is required to provide a sufficient survival of healthy material which will grow' in the spring. The beds are mechanically weeded, the discs of the implement being set so as not to damage the young cane. Line weeding may be done by hand or by flaming. When the winter

I50 AGRICULTURE OF THE SUGAR-CANE

weather arrives in December growth of cane and weeds ceases and they die, while the seed pieces lie dormant until the spring. In March or April the top few inches of the beds are cut off or " shaved " to remove dead material including rotted stubble in the case of ratoons, using a horizontal revolving cutting disc. The sides of the beds are cut away to a width of about 15 in. and the sides loosened, the earth being left in the furrow. In this way soil warmth and aeration are improved. The beds are reformed a few weeks later, when fertilizer is applied, and subsequent cultivation done as required until the cane is too high for the tractors to pass over it. A feature of the system is the high degree of mechanization. Canes are planted by hand, and perhaps a little hand-weeding of the rows is done, but labour is in such short supply that operations which cannot be carried out by high clearance tractors and the special tools designed for this method are omitted.

Age at Reaping The time elapsing between planting and reaping, and from one

reaping to the next in the case of ratoons—in other words the growth period of plant and ratoon crops, varies considerably. It is influenced by climate and rainfall, varietal characteristics, time of planting and operational procedure or the general cropping plans for particular plantations. In most places within the tropics, plant cane occupies the land for a maximum period of 18 months and a minimum of 13 months—more usually the actual age at reaping varies from 16 months to a year. The reaping and milling season is governed by climate, and begins in the dry, relatively cool season of the year, extending to about 5 months or longer, depending upon the quality of the cane and the condition of the land. Similar practice prevails in some areas within the subtropical belt, while in others the severe winter conditions, accompanied by frost, limit the growth period to about 10 months or even less, and make it necessary to harvest and process the crop before it is damaged by very cold weather. In Natal where rainfall is below the optimum for sugar-cane production on an annual basis, the cane is allowed to grow through two wet seasons and thus attains yields which compare favourably with those obtained in the tropics in a shorter time under ample rainfall or irrigation. Again,

F I G . 19.—Applying sulphate of ammonia by hand to plant cane, Jamaica,

[Courtesy of Tate & Lyle Ltd.


in Hawaii, plant cane and ratoons are not reaped until they are two years old, or even more, the resulting crops being correspondingly increased in terms of both cane and sugar.

The ability of the cane to continue growing for extended periods in Natal depends upon its inherent vigour, and a resting period when growth almost ceases, followed by the stimuli of warmer weather and rain which cause the rate of growth to increase. Varietal behaviour influences the period cane requires to mature, and in the case of prolongation of its life it appears to pass through a stage of maturity and checking of rate of growth which is followed by a decline in sugar content accompanied by further growth until a second and later ripening occurs. The cane is not cut at the first maturation because yields in terms of sugar per acre are low; not because the sucrose per cent cane is too low. In other words, the crop pays because it yields more heavily at the end of a longer life.

In Hawaii with varieties selected for long life, the effect is due more to a persistence of conditions favourable to continued growth than to a severe winter check followed by further growth. The continuance of favourable conditions for prolonged growth can be induced by irrigation in hotter climates with a comparatively " warm " winter, as in Jamaica for example. Certain varieties will grow for 22 months or more under such conditions and can be ripened by ceasing to irrigate about 6 weeks prior to reaping. The mill yield of sugar per ton of cane will be found quite normal and similar to other cane cut at the usual age, but yields per acre will be increased in approximate proportion to the age of the cane at reaping. This point is illustrated by the following example :—

Plant cane cut at 16 months, yielded 55 tons cane per acre, with 11.5% recovery of 960 sugar, equivalent to 6.325 tons sugar

/ , T 6.325 X 20 ~j per acre, or 0.79 cwt. per acre/month 7 • Another

field of the same variety, carried over to the succeeding crop and cut at 24 months gave 80 tons per acre of cane, with 11.5% recovery of 96° sugar, equivalent to 9.2 tons sugar per acre, or 0.76 cwt. per acre/month.

While long growth periods are fully justified under what may be termed marginal conditions, where yields would be uneconomi-cally low with annual cropping, the practice in countries where

L


climate and soil provide optimum conditions for short as well as long season, production is decided by economic and climatic factors. There are obvious advantages in allowing the cane to grow over a longer time, and so yield more heavily in terms of sugar with less work on the land. The climatic factor, particularly elements of weather which may cause serious damage and loss to the crop, introduces a risk which becomes greater as the age of the cane increases. While many droughty areas where cane is grown are amply supplied with irrigation, the alternating rainy and dry seasons generally characteristic of hot and humid places where the crop is solely dependent on natural rainfall, bring about variations in growth rate until the cane reaches a stage of maturity usually at the age of 12 to 18 months, beyond which further growth does not take place except under abnormal conditions. In such climates, where rainy conditions occur throughout the greater part of the year, and soil moisture does not become depleted below the point at which wilting takes place, the cane continues to grow, though the rate of growth varies with temperature, but never ripens. The effect is thus similar to that of irrigation, except that rainfall cannot be discontinued at the will of the planter, and. the cane cannot therefore be induced by any artificial assistance to ripen.

In the parts of the tropics subject to the severe type of cyclonic storm called a hurricane in the British West Indies, Fiji and Mauritius, the question of long cropping needs even more careful consideration. Sugar-cane in the earlier stages of growth normally withstands a hurricane with but little damage, but if it were to attain the length of stalk which would occur with a growth period of about 24 months, serious loss might be experienced from storms of high intensity.

Low Standards of Peasant Cultivations The scope for better land use by peasant cultivators is immense.

The food requirements of the increasing population of the world become more difficult to satisfy as time passes, though great areas of fertile land still produce less than half the yield of crops than would be obtained by even a moderate degree of efficiency. This applies with special emphasis to sugar-cane. While the possibility of further increase in yields under the best systems of plantation management is recognized, the immense reserves of peasant


holdings in many countries are being wastefully employed for meagre crops, in addition to which technical standards of sugar recovery are appallingly low. An outstanding example is the Indian Union—in extent, but not alone in degree—for so-called independent cultivators in the West Indies can out-match the ryot of India in misuse of land. The difficulties of changing the methods of the small cane grower, and of bringing about better standards of work and production are fully realized ; but that does not solve the problem. A basic fact is that the peasant cane crops of to-day could be produced upon about one-half of the area now devoted to them with little or no additional effort, and better financial returns. The knowledge of how to do this is available ; it must be put to practical use by improved systems of instruction founded upon practical demonstration on the small cultivator's land, with the work done by him under the direction and with the assistance of capable instructors. Close attention to limited areas where conditions are favourable to success should be given at the start, spreading gradually from such centres to adjoining districts as new methods come into regular use. Instructors should be required to conduct intensive campaigns in strictly limited small areas, and in no circumstances permitted to dissipate their energies by attempting to extend operations outside their district however great the demand may be. Extensive rather than intensive instruction has been the cause of failure of many schemes planned to improve the agricultural practice of peasant cultivators. Apart from the question of yield from effort expended, the poor standard of work of this large body of people has already depleted the fertility of great expanses of land, which can only be restored by speedy action, and continuing determined effort. Statistics are not available to compute even approximately the total area of land devoted to sugar-cane on which these conditions prevail, and generalization is not possible from the few places in respect of which figures are available. Enough is known however to point the danger and apply the remedy.

CHAPTER 10

FERTILIZERS AND MANURES, THEIR APPLICATION AND EFFECT

Uptake of Principal Nutrients Sucrose, which is the product of the sugar-cane upon which the

whole economy of the industry rests, is a chemical substance consisting of carbon, hydrogen and oxygen in combination, none of which is derived from the soil. If the return of all plant residues to the land after the sugar has been extracted from the cane were possible, there would be no depletion of the soil reserves of essential nutrients. This ideal condition does not, however, characterize the conduct of operations. Even where a sugar-cane estate is in close association with a sugar factory and under the control of the same organization, the practical difficulties and expense of returning the factory residues to the point from which they originally derived are insurmountable. Moreover many of the plant constituents undergo changes in the course of the extraction of the sugar, while additions are made in the form of lime and other materials, and a large part disappears in the furnaces in which the fibrous residue, the bagasse, is burnt. Most soils are capable of natural regeneration in so far as all essential plant nutrient requirements are concerned, with the exceptions of nitrogen, phosphorus and potash and of these the two latter are often present in amounts adequate for the support of good crops. A cane crop of 50 tons will remove from the soil the following approximate quantities of replaceable nutrients:

75 lb. nitrogen (N) 50 lb. phosphates (as P205)

150 lb. potash (as K20). These must already be present or be replaced in assimilable form in adequate quantity within the root zone of the cane if succeeding crops are to be fully supplied. Where the sugar-cane planter is unable to obtain and make use of factory residues he will find his land suffers from the continuing drain of plant nutrients to a greater extent than if he were able to return some of the byproduct material to the land.

154

FERTILIZERS AND MANURES, APPLICATION AND EFFECT 155

Sugar Factory Residues Filter mud is the principal convenient and useful sugar factory

residue for returning to the fields. It contains most of the phosphoric acid and some of the nitrogen in the cane. Potassium, or potash to use the generally understood term, mainly leaves the sugar factory in the molasses which is processed elsewhere so that the distillery waste in which most of the potash is finally present is not available in any form for return to the land. Occasional variations occur when, for example, a distillery is operated in association with a sugar factory, but the dunder even then is in most cases wasted. The comparatively rare process of potash recovery from distillery waste is conducted away from the sugar estates which originally supply the molasses, and the potash-rich ash containing about 37.5% K 20 obtained by burning the concentrated waste liquor is disposed of as a fertilizer through trade channels. The small amount of nitrogen in molasses is completely lost. The ash of bagasse accounts for part of the phosphate and potash originally present in the cane, but the high temperatures attained in the factory boiler furnaces bring about their combination with silica and the production of insoluble vitreous material so that they become of no practical value when returned to the land. Surplus unburnt bagasse is a useful soil improver for light impoverished land of poor water retaining capacity. It is bulky material which decomposes slowly, and is costly to handle, transport and distribute. It is occasionally used for the preparation of compost for application to cane fields.

Cond i t ions Essen t i a l t o Effect ive U s e o f F e r t i l i z e r s

Even where useful factory residues are available, the addition to the soil of plant nutrients or fertilizers, particularly those containing nitrogen, is essential for the maintenance of fertility and for the production of good crops.

In addition to nutrient requirements, the plant needs water, which may be supplied by annual rainfall or by irrigation. If the plant is inadequately provided with water it cannot take up nutrients already present in the soil, nor can it derive full advantage from those which are applied in the form of fertilizers. The two essentials, adequate water and adequate nutrients, are com-

i56 AGRICULTURE OF THE SUGAR-CANE

plementary. Both are related to the use of agricultural systems which are strictly suited to the type of soil in which they are conducted, so that a third factor is introduced. The work done on the land in the course of preparation for cultivation not only prepares the soil for the physical support and growth of the plant, but assists in liberating and making available the essential nutrient materials which dissolve in the soil water and are absorbed by the plant. In considering, therefore, the subject of fertilizers and their use in sugar-cane agriculture, it must be assumed that correct methods of land management are practised and that sufficient moisture for the needs of the plant is supplied, any excess being removed by drainage.

Determination of Nutrient Requirements Soils differ remarkably, as has already been shown, in their

fertility status, capacity for regeneration, and capability of stimulating and supporting plant growth. Various methods have been used from time to time to determine the nature and extent of additions which should be made to the soil to replace plant nutrients removed by the harvested crops, and the methods of supplying them for the benefit of succeeding crops. The use of the cane itself as an indicator of its own requirements in these directions has been extensively studied, and as a result new methods of deducing nutrient deficiencies and their extent have been evolved. It has long been known that the appearance of the cane varies considerably with its nutrient status, and that extreme cases of deficiency of one or other of the essentials to its health and vigour are displayed in the leaves and by the habit of the whole plant.

Methods which are coming into extended application for the control of the fertilization of sugar-cane involve the chemical, examination of leaf material in regard to its content of nitrogen, potash and phosphorus. Extensively studied in Mauritius, the method has been further examined in Hawaii and Jamaica. It forms part of the Clement's Crop Log System, and gives results which can be used in determining the nature and rate of fertilizer application. It therefore possesses a very great advantage over methods which depend upon ascertaining the comparative crop yields resulting from various applications of fertilizer to small


plots of sugar-cane, though these are of great value and form an essential part of field investigations as will be seen.

Fertilizer Control by Foliar Analysis

The modem method of determining the nutrient requirements of sugar-cane is by analysis of leaf tissue for nitrogen, phosphoric acid and potash, and comparing the result with standards which have been previously established for the optimum values in comparative field plot trials which show no response to fertilizers and result in the best and most vigorous growth of cane. By this means the results show whether supplies of each of the three fertilizer elements are deficient, normal or in excess of the amounts needed for satisfactory growth and yield, and applications can be adjusted in accordance with the indications thus obtained. The plant tissue used varies in the different countries in which the foliar diagnosis method is applied. In Mauritius the third leaf blade is taken, the partially unfolded one being regarded as the first; in Jamaica, the third fully opened leaf; and in Hawaii, the third, fourth and fifth. It has been found that leaf sampling errors may affect the potash indication. Nitrogen and phosphorus determinations on the second, fourth and fifth leaves give results closely agreeing with those of the third leaf. The crop is sampled under normal growth conditions. If affected by drought, strong wind, unusual rainfall, or other abnormal influences, the value of the results of analysis of the leaf tissue for the determination of the nutrient status of the plant will be impaired, and the indications possibly be quite misleading. In Mauritius, where long ratooning is practised, leaf samples are taken from ratoons only in full vegetative growth at 5 to 7 months of age ; that is midway in the growth cycle. The whole leaf samples, or punch samples taken from the centre of each side of the blade are used for analysis. P. Halais has described in detail the technique used in Mauritius for sampling and analysis in a paper presented to the 7th Congress of the I.S.S.C.T., 1950, with a list of references to publications on the various aspects of foliar diagnosis.

The Method in Practice

The application of this proved method which conserves fertilizers and controls the quantities applied in strict relation to


the actual needs of the crop is extending rapidly. The basic nutrient standards have first to be established for the principal varieties grown in each ecological area. Sampling technique, in regard to the age and condition of the cane, the actual leaf material taken, methods of collecting, preserving and sub-sampling the leaf tissue, and preparation for analysis, must be specified. The chemical examination requires the use of standard methods under highly competent supervision in properly equipped laboratories, and staff capable of conducting large numbers of analyses with speed and accuracy. Many large plantations are carrying out this work in their own laboratories as a part of the scientific routine control of fertilizer applications. Smaller estates and farmers need central laboratories to conduct the work on their behalf, such as the one established by the sugar industry in Mauritius in 1948.

Relation to Field Plot Trials It does not replace the regular types of plot trials which are

designed to determine the response of the cane to different levels of fertilizer dosage. Foliar analysis carried out on leaf material from cane in such trials is used to establish the standards of N.P. & K. content of the leaf tissue on which advice regarding the rates of application of fertilizer on a field scale can be based in relation to the results of the leaf sampling technique. Experimental plots thus provide amongst other information the references necessary to interpret and apply the foliar diagnosis method. The approximate amount of increase or reduction in fertilizer application can be determined by comparisons made with the indications of the field plot trials, and in that way bring about a speedier and more extensive correction of fertilizer practice than is possible by the field plot method alone.

The standards for composition of leaf material on a dry basis found to apply in Mauritius are quoted :

PzOs K20

o-55% i-75% o.45%-o-55% I . 2 6 % - I . 7 5 % o.35%-o.45% o.75%-i.26%

o-35% °-75%


Farmyard Manure and Artificial Fertilizers Farmyard manure still finds a place in the cane fertilizing pro

gramme of estates and cultivations where animals form the major source of power for work on the land, and for transport of cane, but it is no longer regarded as an essential for the maintenance of soil structure, fertility, and the production of good crops of cane. The availability of artificial fertilizers, the ease with which they can be applied in regulated quantities suited to the needs of the soil and the crop, and the proof by experiment and experience that their use in the proper kinds and quantities does all and more than farmyard manure ever did has in recent times completely altered plantation practice. It has been shown that artificials can match farmyard manure in cane and sugar yields in good soils, and give better results on poor soils. The effect of mechanization, which has displaced animals completely in some areas, and to a great extent in others, has not, as was thought by some authorities, been accompanied by a disastrous lowering of fertility levels. Indeed, the contrary has occurred ; yields have increased ; and there is no evidence of any decline in the qualities of the soils.

There are no sound reasons for the retention of livestock for use on cane plantations because of any contribution they may make to the land in the form of manure. It may be convenient or economic to use livestock, in which case full use should be made of the manure, which is undoubtedly valuable when properly conserved and effectively applied. The essential point is that just as the large scale use of farm animals has proved uneconomic in extensive cane production areas, so has the cost of farmyard manure increased far beyond its actual value as a fertilizer. It is by no means intended to deprecate the value of organic residues for the amelioration of soil and the increase of nutrients available to plants. The use of farmyard manure on the larger estates is expensive and it suffers from the disadvantage of being an unsuitable medium for the application of regulated amounts of the fertilizers it contains in relation to the actual requirements of the cane. When available it should therefore be used in ample quantities on limited areas where transport to the field, and distribution on the land are relatively low in cost. On small cultivations where animals are used everything possible should be done to conserve the manure and apply it effectively to the cane land.


Composition of Farmyard Manure .

The composition of farmyard manure varies with the type of animal, the nature of the food ingested, the litter used, the method of making and conserving the material and its age. The average results of a large number of analyses conducted at Rothamsted are quoted:

Water 76% Nitrogen 0.64% (15 lb. per ton) Phosphate (as P2055) 0.23% ( 5 lb. per ton) Potash (as K20) 0.32% ( 7 lb. per ton)

The composition of the cattle manure produced on cane farms is closely similar, but losses of nitrogen occur more rapidly under the influence of the higher temperatures, while as a general rule the methods of making and conserving the manure are less carefully conducted. The wastage is therefore usually high, especially when no special arrangements are made to prevent loss of the urine and decomposition of the urea.

Loss of Nitrogen from Farmyard Manure .

The two most highly regarded constituents of farmyard manure are nitrogen and humus, and its utility when applied to the soil is mainly related to the increase of humus in the soil and the improvement of the water retaining capacity of the land when adequate amounts are applied. The nitrogen is mainly present in the form of urea, which is rapidly decomposed into free ammonia and carbonic acid, both of which almost entirely escape into the atmosphere in the form of gases. In the process of this change, ammonium carbonate is formed as an intermediate product which breaks down when the liquid containing it evaporates. It is also subject to decomposition by the action of bacteria which first convert it into nitrate and then to free gaseous nitrogen, a process called denitrification, which is affected by the condition of the manure. These are but two of the complex series of changes which occur, but they are sufficient to indicate that farmyard manure as ordinarily prepared is by no means an effective way of conserving combined nitrogen.

FERTILIZERS AND MANURES, APPLICATION AND EFFECT I O I

Organic Dressings The question of whether or not to use farmyard manure in

cane land is decided therefore by factors largely unrelated to the fertilizing value of the material. Where dressings of organic material are desirable they can be provided in various ways, among which are the composting of organic residues, the use of factory waste, particularly filter mud and bagasse, and to some extent under favourable circumstances by the practice of green manuring and trash conservation. In no sense is it intended to convey that the application of organic matter in suitable decomposed form should be discontinued; rather should it be encouraged and developed, the essential point being that it must be economic, and only those methods can be economically used which provide the requirements of the cane cheaply and effectively.

Fly-Penning The folding of cattle in temporary enclosures in the cane fields,

called " fly-penning " is a method used in parts of the West Indies, particularly in Jamaica with the object of improving the fertility of small and usually comparatively poor sections of the area to be replanted. Each pen is bounded by a post and wire fence and the animals are confined during their rest periods, being watered before and after as it is not always possible to supply water to them in the fold. Litter consists of cane trash, bagasse, and the residues of the feed which is usually cane tops and grass supplied to the animals in the pen. The theory is that the excrement is deposited on the land in the place where it is needed, and that the decomposition of the litter and unconsumed food under its influence adds substantially to the humus content of the soil. In practice the method is costly, wasteful and less effective than the use of properly prepared f.y.m. carted out and applied to the fields. Decomposition of the urea, and denitrification are very rapid; very little humification of the litter can occur; and a high proportion of the food is trampled and spoiled. The soil is temporarily improved by the other nutrient salts voided in the excreta and by the litter which is subsequently turned in when the area is ploughed. The expense of erecting and removing the fences, transporting Utter and feed, and attendance (the control of movement and care of the animals) far outweigh the benefits derived.


Application to Plant Cane The practice in regard to the times and methods of applying

fertilizers varies considerably. Studies have been made of the effects of supplying the indicated requirements of the cane in two or three divided doses as compared with a single application. In general little if any advantage has been shown to attach to the use of the former method. Apart from the nutrient effect on the cane, the damage to soil tilth brought about by additional movements over the land for the supply of the full amount of fertilizer in two or three parts is a definite drawback. For plant cane the dropping of the fertilizer into the open furrow at the same time that the setts are planted has been found entirely satisfactory. To be most effective phosphates and potash should be placed in the root zone, while nitrogen may be applied to the surface, though again there is no evidence that nitrogen is less useful when buried. It is desirable that the germinating buds should not be in direct contact with concentrated fertilizer, and this may be avoided by the placing of the fertilizer in relation to the sett. With mechanical planting the full dose of fertilizer is often dropped at the same time as the sett, a practice which does not appear to affect germination adversely.

F e r t i l i z i n g R a t o o n s The fertilizing of ratoons is more troublesome when the cane is

not burnt prior to reaping unless the material is scattered on the trash over the cane rows, which is a method occasionally used. When cane is burnt surface cultivation of the ratoons often takes the form of a light chiselling or ploughing on each side of the cane row, and it is a comparatively simple matter to apply fertilizer mechanically at the same time. When trash is left on the field it has been found best to move it from immediately above the cane row, though if not too dense it may be left in position and the fertilizer scattered over it where the cane is grown under conditions of natural rainfall. Where surface irrigation is practised, it is necessary in any case to cut furrows either after removing the trash from the cane row, or by cutting through it with a specially designed implement which makes the furrow at the same time. It is a simple matter to combine the application of fertilizer with these operations.


Placement of Fertilizers and Aerial Application Experiments in Hawaii on phosphate placement using radio

active phosphorus have clearly demonstrated the advantages of applying phosphates in the furrow with the seed pieces. Similar studies showed that phosphate sprayed on to the cane leaves from the air stimulated the development of secondary shoots. It was found that the phosphorus was translocated from the leaves down the stalk. Marked response was shown to spraying with a potash fertilizer in another trial. Applications of nitrogen as urea in small quantities from the air after the cane had closed in were successful. Less nitrogen was required than with application to the soil. It is concluded that plant and ratoon crops should receive all the phosphorus, and from one-third to one-half of the nitrogen and potash needed, subsequent applications of N. and P. being given from the air in quantities determined by the needs of the cane.

Fertilizers in Solution The distribution of soluble fertilizers in irrigation water is

successful under effectively controlled water distribution. In a similar way soluble artificials may be applied by overhead irrigation.

Disadvantages of Mixtures The use of mixtures of N.P. & K. in various preparations is still

extensively practised. The mixtures are designated by sequences of numbers such, for example, as 12 : 4 : 8, which indicates a fertilizer containing 12% of nitrogen, 4% of phosphoric acid and 8% potash (K20). When using the three essential fertilizers in this manner it is impossible to apply the correct amount of each in relation to the available quantities present in the soil and the requirements of the crop, which as has been shown vary enormously within quite small areas. The danger is therefore that excessive quantities of one component may be distributed in order to secure an adequate supply of another, with accompanying waste of a valuable material and actual loss of money expended. Modern methods of field experimentation are capable of indicating within narrow limits the actual crop requirements of fertilizer from field to field. Fertilizer mixtures do not always meet the nutrient requirements of the plant satisfactorily even when the


constituent elements are necessary to supplement soil deficiencies. The proportion of the mixture needed for varying conditions will not be constant for one plantation, and often not for a group of fields. One or other of the elements will be applied in wasteful quantities unless special mixtures are provided for each type of soil and for each group of varying conditions. The placement of the fertilizer in relation to the plant is important, and though it is an advantage to broadcast a part of the total application, applying the balance near to the cane, the phosphate part of any mixture should be buried, while nitrogen appears to give the best results when placed on or just under the surface. Nitrogen should certainly be used separately, and mixtures of potash and phosphate only under advice based upon investigation as is done in Queensland where three types of PK (phosphate-potash) mixtures have been found to meet the range of differing soil conditions satisfactorily.

Compound Fertilizers Artificials, particularly the nitrogenous ones, are obtainable in

many forms which vary in their content of the essential fertilizing element, N.P. or K. as the case may be, in the readiness with which it becomes available to the plant, and in its residual effect both on the soil and the succeeding crop. It is not always true that any nitrogenous fertilizer will satisfactorily replace others, and though under some conditions alternatives can be used comparative trials under proper control are necessary to determine their relative usefulness and value to the crop, and the actual cost per unit of nitrogen in relation to its effect upon yield. These observations apply also to compounds containing more than one principal fertilizer element, such as ammonium phosphate, for example. Though there may appear to be an advantage in applying two fertilizers in one as it were, before doing so on any extended scale it is essential to know that the chemical nature of the fertilizer is suitable, that growth and yield responses will be increased, and that both elements are required by the soil to support the crop.

A replicated experiment conducted on an irrigated plantation in a clay soil with a clayey subsoil to compare ammonium sulphate with ammonium phosphate disclosed no advantage in the use of the latter, but on the contrary a drop in yield attributed to the


phosphate was recorded, though sulphate of ammonia alone caused significant increases in both cane and sugar. It is obvious that phosphorus, in the form of the ammonium salt was unnecessary, and the additional expense wasted. Further investigations in this particular case disclosed that phosphates in any form had no appreciable effect. On the other hand marked responses to ammonium phosphate have been obtained on soils deficient in available phosphates and nitrogen.

Green Manuring Though green manuring has been practised from the earliest

times, its effects upon the soil and succeeding crops are not yet fully understood. It does not produce any significant increase in the humus content of the soil and under hot tropical conditions any slight increase brought about by ploughing in such organic matter rapidly disappears. Plant nutrients taken up during the growing period and returned to the soil when the green crop decomposes after being ploughed in, combined with the effect of the products of decomposition upon soil minerals thus making plant nutrients available, appear to be the principal contributions to soil improvement. Apart from these effects, great advantages are the protection given to the soil during the period between the first preparation of the land after it has been thrown out for replanting, and the ploughing in of the green manure crop just before planting with cane ; and the suppression of weeds. The subject requires careful investigation in relation to sugar-cane agriculture. The fixation of nitrogen by the symbiotic bacteria which live in association with the roots of leguminous plants is regarded as an important contribution to the nutrition of the succeeding crop of cane when there is only a very short interval between ploughing in of the legume at the time of flowering and the planting of the cane. Thus in Natal the nitrogen requirements of the plant crop of cane are provided by the leguminous crops grown previously, no additional nitrogen being applied. The effect seems to disappear fairly quickly as normal dressings of nitrogen are given to ratoons.

Fertilizers Containing Nitrogen The solid compounds used as nitrogenous fertilizers vary in

their content of nitrogen, in their behaviour in storage and in their


effect upon the soil. Anhydrous and aqueous ammonia have largely replaced other forms of combined nitrogen in Louisiana and elsewhere during recent years. The proportion of nitrogen in commercial fertilizers commonly used and the amount needed to provide 10 lb. N. per acre are shown below :—

Some Factors Affecting Choice The price of 1% of nitrogen in a compound is the " u n i t "

cost, which is used to compare the relative costs of the various nitrogenous fertilizers. The unit cost of nitrogen in sulphate of ammonia at £40 per ton is thus 38s. 10d. very nearly. Phosphatic and potassium fertilizers, as well as mixtures, are evaluated in the same manner.

Though cost considerations enter very largely into decisions as to choice, certainty of supply, bulk, weight, physical condition, ease of application, and long term effect on soils are important. Louisiana in 1947 was faced with shortages of nitrogenous fertilizers which led to the use of ammonia, already proved to be a satisfactory source of nitrogen for sugar-cane. It happens that this is also the cheapest form in which fixed nitrogen can be purchased there. The cost of transport is important, and though in general the more concentrated nitrogenous compounds can better


sustain higher charges, anhydrous ammonia cannot at present compete with sulphate of ammonia where shipment by sea is involved. Chilean nitrate, which in some cases is cheaper on a unit basis than sulphate of ammonia, absorbs moisture from the air under humid conditions and may liquefy. Losses occur and difficulty in handling and applying it to the land are experienced. Nitrate of soda causes undesirable changes in the soil structure when used in dry areas on irrigated land. Commercial calcium cyanamide contains free carbon, lime and traces of other substances. It is marketed in granular form, being specially treated to make it more convenient to handle. Other forms of nitrogen are preferable for use with sugar-cane provided that differences in unit cost are not too great.

Effects of Nitrogen In the presence of adequate moisture nitrogen stimulates and

increases the growth of sugar-cane, enables the plant to take up other plant nutrients, and in properly regulated quantities brings about the production of greater yields of cane and sugar. The visible effects are increased vigour of the cane and a darker green of the leaves. When applied in excess the quality of the juice is impaired. This effect is related to the continued vegetative growth induced by the nitrogen and the attendant delay in maturing. Accompanying the increase in yield of cane is the production of a greater amount of leaves which in turn give rise to more trash. This with the development of an extended root system to support and nourish the heavier growth results under suitable conditions of crop management in augmenting the organic constituents of the soil. In this way the general level of fertility is maintained, and even improved, though the applied nitrogen has little or no direct effect upon the succeeding crop of cane. Nitrogen alone may increase the susceptibility of the cane to disease unless the phosphates and potash available in the soil are adequate for its needs. If not, the deficiencies should be supplied by applications of the appropriate fertilizers.

Rates and Methods of Application Nitrogen in sufficient quantity is essential to the production of

satisfactory crops of sugar-cane. Even rich virgin soils become


quickly depleted of supplies, and after a few crops the cane shows the stunted growth, pale leaves and general lack of vigour characteristic of nitrogen deficiency. Where green manuring is practised between planting cycles the plant or virgin crop often receives no additional nitrogen, though in some places 30 to 40 lb. per acre are applied. With no green manuring nitrogen dressings range from 40 lb. per acre upwards, and ratoons are given 45 to 100 lb. Local practice varies considerably, in accordance with the actual requirements of the crop as ascertained by field experiments and foliar diagnosis, or by the application of rule of thumb methods based on experience, a system which happily is rapidly disappearing.

The modes of applying nitrogen vary considerably and include broadcasting, surface application near to the plant, placement in shallow cuts made by a hoe and covered, distribution in furrows, in solution in irrigation water, and by injection beneath the surface in the case of ammonia. The method of using the solid nitrogenous fertilizers appears to have little influence on their effectiveness, except that placement near to the cane rows is better than broadcasting. Manual and mechanical applications are made in one or more doses at varying times and intervals. Experimental evidence indicates no advantage of any particular method for the solid compounds. It makes no practical difference whether the material is applied to the surface or buried to a depth of a few inches. Comparison of the effects of the same amount of fertilizer supplied in one, two or three doses discloses no significant difference. The important considerations are the use of correct amounts, strictly related to the ascertained requirements of the cane, convenience, and cost, with constant attention to the preservation of tilth. In Louisiana and Natal comparisons of the effects of the same quantities of nitrogen provided by different fertilizers showed no significant variation in crop response. The form in which the nitrogen is applied is therefore largely decided by its cost per unit at the place where it is to be used. Inorganic nitrogenous fertilizers applied at the time of planting may cause injury, through the developing shoots and roots coming into contact with too concentrated a solution, so that when the nitrogen dressing is given then, proper placement is important. Organic nitrogen compounds do not harm the germinating setts.


Aqueous Ammonia Where ammonia is available in large quantities at a lower cost

than other forms of fixed nitrogen it is rapidly replacing them for direct application to the land. The aqueous solution as supplied in tank cars by manufacturers in the U.S.A. contains 31.1% ammonia by weight, and is used in that form as a commercial fertilizer in Louisiana and elsewhere. It can be stored in tanks under 6 to 10 p.s.i. pressure, being applied to the soil from a tractor tank by a pump adjusted to deliver the correct amount.

Ammonia solution 23 % is prepared by bubbling the anhydrous gas into water in a mixing tank, the liquid being circulated through a cooling coil as water and gas are added until, the required concentration is reached, when the batch is pumped into a storage tank. Solution of this strength does not develop pressure below ioo° F.

Anhydrous Ammonia is a colourless alkaline gas at ordinary temperatures, which liquefies under pressure. It has a sharp, penetrating, choking odour, and causes irritation to the mucous membranes. Special care is therefore necessary in using it, and operators at storage installations should be protected by gas masks, and readily available supplies of water. Bulk storage tanks must be capable of withstanding working pressures of 250 p.s.i., protected from direct sunlight, and filled to not more than 85% capacity (Fig. 22). Transport tanks for conveyance to the fields are usually of 1,000 U.S. gal. capacity, and these are used to charge tractor tanks holding no gal. which deliver through control valves to soil applicators. Two rows can be treated at once. The equipment used must resist the action of ammonia gas and solution, but it does not affect the use of the tractor for other work. The depth of application of both forms is 6 to 7 in. It is important that the soil should be in good tilth.

Phosphates Phosphate fixation. The presence of phosphates in soluble form

in the soil is essential to normal growth and ripening. Where supplies are deficient the addition of suitable phosphatic fertilizers becomes necessary, but only properly conducted investigations can provide information regarding the quantity, form, and method


of application of the material. Some soils are able quickly to convert applied soluble phosphates into insoluble compounds, so that the plant derives little or no benefit because these insoluble phosphates break down very slowly into more soluble forms and the plant is unable to obtain its requirements. The fixation of phosphate by clay, and by iron, aluminium, calcium and silica in the soil by chemical combination and absorption is mainly responsible for this effect. The decomposition of insoluble phosphates occurs under the influence of carbon dioxide and humic acid. This may be followed by further partial fixation by clay which reduces the availability. The effect of applied soluble phosphates on the cane can thus be more or less completely prevented by reactions which occur within the soil before the roots are able to take up a sufficient amount to benefit the plant. The use of granular forms of phosphatic fertilizers partially overcomes the difficulty. The admixture of phosphates with organic material, such as compost, filter mud, and farmyard manure before applying to the land has been found beneficial. Apart from interactions with the organic matter influenced by the micro-organisms present, the applied phosphates are to a great extent isolated from the soil particles which would otherwise bring about the fixation so that the plant is able to absorb its requirements more easily. Where phosphates have been used in large granules and lumps placed in the root zone, the feeding roots have been observed to penetrate the material. The subject of phosphate fixation and availability in cane soils is not fully understood, and it continues to receive close attention by research workers.

Effects of Phosphates The effects of phosphates on the cane are to stimulate rooting

and tillering, and as with all other plants the processes of synthesis and normal growth need adequate supplies. In areas of low rainfall the influence on quick root development is important. The root system is stimulated to penetrate more quickly to the deeper layers of soil where better supplies of moisture are available.

Nitrogen and phosphates have been found to be complementary to one another in their effect upon plant growth. One in the absence of adequate supplies of the other depresses yields, and this fact appears to be responsible for former errors in assessing


the apparent need for their addition in the form of dressings. Recent investigations have shown remarkable responses to combined applications of nitrogen and phosphates on some soils.

B. A. Bourne has found that phosphorus deficiency in the low mineral peat soils of Florida causes susceptibility to root rot, associated with stunting of the cane. Triple superphosphate (47% P205) at 165 and 330 lb. per acre significantly increased the phosphorus in the juice, the higher application being the more effective. In plots receiving no phosphate acute leaf symptoms of phosphorus deficiency were apparent, and in combination with the stunted growth, contrasted remarkably with the cane in treated plots. All the leaves in phosphate deficient plots were pale green to yellow, and the dying and drying of leaf tips and margins occurred. Visual inspection by trained observers readily detected indications of deficiency, which in all cases was confirmed by leaf analysis of typical stools.

The Phosphatic Fertilizers The forms in which phosphates are used comprise rock phos

phates, super- and triple superphosphate, and bone manure, all of which contain one or more of the three phosphates of calcium ; and ammonium phosphate. Deposits of phosphatic rocks in different forms provide the source of by far the greater proportion of the phosphatic fertilizers. Although finely ground rock phosphate is used directly it is very insoluble, and is only suitable for acid soils. The treatment of natural rock phosphate with sulphuric acid converts part of the insoluble tri-calcium phosphate into mono-calcium phosphate and calcium sulphate (gypsum), called superphosphate. The fertilizer equivalent of phosphatic materials is determined by the amount of phosphoric anhydride, or phosphorus pentoxide (P205) present in combination in soluble form, the trade term being " phosphoric acid." Superphosphate varies in its content of soluble P 2 0 5 from 14 to 21%. In Britain, Australia, and certain other countries, the guarantee of quality is in respect of water soluble P2O5, but the U.S.A. and South Africa are among those which use the " citric soluble " basis, which is the percentage in terms of P 2 0 5 soluble in a 2% solution of ammonium citrate.

When phosphoric acid is used in place of sulphuric acid for the


treatment of rock phosphate, a product containing a much higher proportion of P 2 0 5 with no gypsum, is obtained. Known as triple superphosphate because it contains nearly three times as much soluble P 20 5 as ordinary super, it is manufactured in the U.S.A. almost exclusively. The citric soluble P 20 6 in triple superphosphate is about 47%.

Mono-ammonium phosphate containing 12% N. and 50 to 54% P 20 5 is manufactured for use as a compound fertilizer alone and in mixtures. Basic slag is a by-product of the steel industry largely consumed as a fertilizer in Europe, but it does not appear to be used for sugar-cane. Guano is the weathered product of the excreta of birds and varies considerably in composition. Nitrogen which is originally present is progressively lost, and the value of older deposits is determined by the soluble P2O5. Finely ground bones and bone meal are used in the preparation of mixtures.

Rates and Methods of Application

Where response to phosphate application has been indicated, the dressings are usually given in the furrows at the time of planting in amounts ranging upwards from about 40 lb. per acre available P205. The most commonly used forms are super and triple superphosphate. The former is used up to 600 lb. per acre, equivalent to about 130 lb. soluble P205 . If a potassic fertilizer is to be used, it can be added at the same time, as both kinds of fertilizer give the best results when placed well down within the root zone of the cane. This is particularly desirable in soils which bring about phosphate fixation.

Applications to ratoons are best made in furrows at one side of and near to the cane row as soon as possible after the reaping of the previous crop. No advantage has been found in placing phosphatic (or other) fertilizers on both sides of the row.

It will be realized that the supply of soluble phosphates to meet the requirements of satisfactory cane growth is generally more difficult than the correction of nitrogen and potash deficiencies. Foliar diagnosis will show whether the plant needs this nutrient, but the complications of soil reactions make it essential to conduct local investigations to ascertain the most effective manner of providing phosphates in readily assimilable form.


Potassium Effects of Potassium

Potassium is essential to the normal growth process of the sugar-cane, and in particular the synthesis of carbohydrates and sugar in the leaf, with their movement to the storage cells in the stem. The manner in which potassium influences these functions has not yet been satisfactorily explained. If it is seriously deficient the cane displays obvious signs of distress. The older leaves die back from the tips and margins, and the upper surface of the midribs develops a distinctive red colour. When these symptoms are observed, there have been progressive soil depletion and reduced crops for some time previously. The plant may not exhibit visible symptoms of slight deficiency, which can however, be detected by examination of the juice, by soil analysis, and by leaf analysis. P. E. Turner found that when the exchangeable potash in the soil (as K20) fell below go parts per million, it was profitable to apply potassic fertilizer. Recent work in the West Indies, Mauritius, and elsewhere has disclosed serious potash deficiencies, though visual evidence has not been apparent in all cases. Foliar analysis has successfully shown where these conditions exist, and has confirmed the response of the cane to the application of potash, which has brought about increased yields of cane and sugar. An indication of potash deficiency in an apparently normal plant can be observed by immersing the terminal end of the leaf while still attached to the plant and with the tip cut off, in a dilute solution of potassium sulphate contained in a waxed envelope. The leaf absorbs the solution and develops a distinctly greener colour.

Adequate up-take of potassium increases the resistance of the cane to disease. Potassium and nitrogen are necessary in sufficient quantity for either to exercise its most beneficial effect. Potassium applied in excess of the current crop requirements is retained in the soil with little loss, and may benefit succeeding crops. It is possible thus to build up potash reserves in the soil. Foliar analysis discloses this condition if it is present, and makes it possible to regulate additions of potash in accordance with the optimum needs of the crop. This is economically important because of the high cost of potassic fertilizers, and the difficulty often experienced in procuring them. The plant does not take up


the whole of the potassium applied so that additions must be about twice as much as actual requirements to obtain the best results.

Fertilizers Containing Potassium Potassic fertilizers are marketed and used on a basis of their

content of potassium oxide, K20, commonly known as potash, which, however, none of them contains or supplies as a definite chemical compound. Though the method has no scientific basis it is a convenient manner of evaluating different kinds of fertilizers containing potassium, and of determining the amount to apply to the soil. Plants absorb potassium in its ionized form, uncombined with any other element. Potassium salts are very soluble, and for this reason almost all the potash in the cane leaves the factory in the molasses, which normally contains about 3% K 2 0. This byproduct is not generally processed in conjunction with the sugar factory, and even where rum and alcohol are produced on the spot, the distillery waste is not always applied to the land. In contrast to phosphates which mainly appear in the filter mud, now widely used as a fertilizer, the potassium salts derived from the cane are very rarely returned to the soil. Marked responses to the application to the land of the waste liquor from distilleries have been obtained, and have been proved to be due to potash.

The two principal commercial fertilizers containing potassium used for sugar-cane are the muriate (or chloride) and the sulphate. Chilian potash nitrate containing 15% N. and up to 18% K20 is also used to some extent. The muriate and sulphate vary considerably in purity, which affects their content of K 2 0 .

Sulphate of potash (Potassium sulphate) Sulphate of potash (Potassium sulphate) Sulphate of potash (Potassium sulphate) Muriate of potash (Potassium chloride) Muriate of potash (Potassium chloride) Muriate of potash (Potassium chloride) Muriate of potash (Potassium chloride)

The assertion is often made that the sulphate is superior to the muriate in its effect on the cane, but there is no evidence to support the view that potassium salts differ in this respect. It is, however,


possible that the impure commercial products may contain small quantities of other compounds which benefit the cane, particularly magnesium. The cost per unit of K 2 0 is generally lower in the muriate than the sulphate, while the former is usually more readily obtainable.

Evolution of Potash Deficiency Fertilization practice in regard to potash has changed in many

places in recent years, particularly in those areas where pen manure (f.y.m.) was extensively used. The general picture of sugar-cane field methods then differed greatly from those of to-day. Soil reserves were not so heavily drawn upon, and yields were lower. Potash deficiencies were not observed, and if they did exist were in many cases not recognized. In some instances field experiments disclosed no response to applications of potash, and it was asserted in Jamaica, for example, that added potash was unnecessary. The dynamic qualities of the soil are particularly in evidence in regard to the availability of potash. Intensification of land working methods, new cane varieties, and the heavy applications of nitrogen have resulted in much heavier crops which have taken up potash at a greater rate than soil reserves become replenished, and potash deficiency has had to be satisfied by applications of potassic fertilizers. These have led to spectacular crop increases in Trinidad and Jamaica on some soils.

Cycles of potash supply in some cane soils have been observed ranging from deficiency to excess over periods of a few years. The regular dressings to plants and ratoons have resulted in significant increases in yield both in experimental plots and on a field scale in the early part of the cycle, followed by no effect from potash applications which were then discontinued with no apparent decline in yield for two or three crops, after which there were indications of renewed potash deficiency.

Rates and Methods of Application The methods used for testing the need of cane for potash and the

responses obtained by applying it will now be familiar to most field staff on sugar estates. The foliar diagnosis system, related to replicated field experiments of proper design for testing fertilizer responses at different levels, is used to determine the need for


potash alone or in association with nitrogen and phosphates. Where deficiencies have been thus observed, the application of potash in the estimated quantity needed may be made at the time of planting the cane, or as quickly as possible after reaping for the ratoon crop. The amounts applied range from about 100 lb. K20 for short period cropping to 300 lb. per acre for long growth periods as in Hawaii, in one, two or three doses. It is often used with phosphates, as in Queensland where standard potash-phosphate mixtures are used for the three main soil types. Potassic fertilizers may be placed on the surface or in furrows, the latter being preferable, and essential if a mixture with phosphate is used as the latter to be most effective must be applied in the root zone.

Other Essential Elements In addition to nitrogen, phosphorus, and potassium, which are

the plant nutrients in greatest demand by the cane, deficiencies of other elements essential to plant growth occur ; and corrective treatment may be necessary to restore the soil conditions most favourable to crop production. Acid soils need dressings of lime, usually given as carbonate in the form of finely pulverized limestone or calcareous marl after ploughing and before harrowing the land that is to be replanted with cane. Coral sand is also used when readily and more cheaply available. Filter mud contains lime in a very finely divided state, 1 long ton being equivalent to 45 lb. or more of calcium carbonate. It is important to replace in this way the calcium lost from the soil by leaching. The rate of loss is increased by the use of sulphate of ammonia in approximate proportion to the quantity of that fertilizer used. Soils which are naturally rich in calcium carbonate are exceptions to the practice of liming, which is otherwise necessary to provide sufficient calcium for the crop, and to correct acidity. The latter condition prevails in acid clay soils which may require dressings up to 5 tons of ground limestone per acre in each planting cycle to improve their texture.

Calcium in the form of sulphate (gypsum) is occasionally necessary to reclaim soils that have been damaged by excess of sodium salts over a long period. Sodium replaces calcium in clays, making them sticky, alkaline, and impermeable to water. Development of these conditions needs careful watching and correction in con-


nection with the continued use of fertilizers containing sodium, and certain irrigation waters.

Magnesium is often a constituent of limestones, and is present in some commercial potash fertilizers and in farmyard manure. With the changes in fertilizer practice, magnesium deficiency is likely to become apparent to an increasing extent, and it may be necessary to correct it by the inclusion of magnesium salts in the fertilizer programme.

Minor and Trace Elements Increasing attention is being paid to the function of minor and

trace elements in the nutrition of the sugar-cane. The great changes in agricultural practice seem again to be responsible for the exhaustion of soil reserves of the very small quantities of these materials necessary to produce healthy growth and satisfactory yields. It is possible that the more extensive use of farmyard manure on the smaller plantations before the days of intensive mechanization kept the land supplied with adequate amounts of the minor and trace elements required by the cane, while the lower yields then charactertistic of plantation practice did not cause exhaustion. Though research has been conducted on this subject much more work is necessary in regard to the part played by such elements, the manner in which deficiencies can best be supplied, and their relation to other essential nutrients. Reference is made in Chapter 4 to the special needs of the organic soils of Florida. Manganese and boron deficiencies have been investigated. Iron is often not available in adequate amounts, and the relative importance of elements of which minute traces only may be necessary is not understood. It is of the highest importance that the major nutrients should be in correct balance for the requirements of the crop. Excess or deficiencies of one or another may lead to poor yields, lack of vigour and higher susceptibility to disease. The possibility of similar effects being induced by the presence or absence of trace elements requires careful study, which has indeed been commenced. A new approach to these investigations has been provided by radio-active isotopes of elements which are taken up by the plant, and their movement in the plant traced by their recovery and indentification from the different tissues.

CHAPTER 11

WEEDS AND THEIR CONTROL

The Menace of Weeds The enemies of the planter are of many kinds, each requiring

special modes of attack and defence to minimize or avoid their adverse effect upon the crop. Weeds take a high place in the list or these enemies. If they are not effectively controlled they directly reduce yields of cane and sugar, and indirectly assist infestation by pests and diseases which in turn add to the damage and loss. In general, conditions which favour the growth of sugar-cane also stimulate and increase the vigour and density of weeds, whether they belong to the class of useless plants normally so termed, or are plants out of place, such as numerous varieties of grass which flourish in company with their giant relative until he gets big enough to choke them by preventing the access of sunlight to them. There are few places in the world where commercial varieties of cane could survive in uncontrolled competition with these natural enemies, as is clearly demonstrated by the rapid disappearance of most of the cane growth in fields which are thrown out for replanting and are left for a time before being ploughed. The reduction in actual yield of crop by weed infestation is combined with increased trouble at harvest, because of the greater difficulty encountered in reaping. Cutters display reluctance amounting m some instances to refusal to reap cane choked with weed growth which may be so dense as to produce a tangled mass from which the cane can only be got out with great effort. Extreme cases of this nature may be rare, but they still do occur. Apart from the damage to his own interests, neighbouring areas are menaced by the planter who neglects to cope with his weed problem, as heavy weed growth allowed to develop unchecked to matunty can cause re-infestation of land which has been kept under effective control.

Constant attention to weed suppression is most necessary under natural rainfall conditions, and is then often troublesome to carry out because the land becomes too wet to permit any surface work amongst the cane. Luxuriant growth occurs in field traces and

178

WEEDS AND THEIR CONTROL 179

intervals ; on headlands, exposed banks and uncultivated land. All such places in and near the cane fields must be kept under control. Irrigated land is cultivated after each application of water until the cane has formed a canopy and any weed growth between the rows is then checked by the one operation. In general, the weed problem on other parts of irrigated plantations offers little difficulty, except occasionally after rainy periods when prompt action will deal with it and assist in keeping planted land free. Under both natural rainfall, and irrigated conditions, normal cultivation methods formerly performed most of the work of weeding, and indeed still continue to do so, although chemical control is rapidly being developed.

Weeds are of annual and perennial types. The former are propagated by seeds. They are more easily destroyed as once the portion of the plant above ground is killed no further growth occurs except from seeds. Perennial weeds are generally propagated by the root stocks, which develop new shoots when the aerial part is destroyed. Annual weeds should therefore be dealt with before they seed, preferably in the very earliest stages of growth, while perennial weeds need to be removed, roots and all, or completely poisoned if they are to be prevented from growing again.

Methods of Control Efficient weeding procedure suppresses weed growth before the

germinated shoots appear above the surface of the ground, but with what may be termed mechanical methods, this cannot for various reasons be consistently achieved in practice. The detrimental effect of the frequent movement of men and machines over the surface of the land, discussed in Chapter 9 applies with equal force to the attack on the weeding problem, so that with such methods the weeds are often dealt with less frequently than their density and growth really require because of convenient arrangement of other and associated cultivation operations related to the stage of development of the cane. The planter therefore endeavours to strike a balance between the three considerations of cane growth, weed infestation, and soil condition, with the object of reducing the number of operations and the ultimate cost of the cane.

The methods of control fall under several heads, and in most

i8o AGRICULTURE OF THE SUGAR-CANE

plantations more than one method is normally used. The earliest of these, manual weeding by the use of a hoe is still largely practised, and is the best way of dealing with the weeds which occur in the cane rows by any form of land working implement. Thus it is found that manual hoeing is extensively combined with inter-row cultivation by animal drawn implements and mechanical power. This line weeding, as it is called, was troublesome, and often damaging to the young cane until the introduction in recent years of flame weeding and the use of weedicides.

Some weeding implements are designed to work on each side of the row, and to remove weeds in the row at the same time. Lightly constructed spring tines are fitted between sets of discs or heavy tines on each side, and exercise a scratching effect along the cane line, thus removing weeds without damaging the cane.

The old West Indian practice of weeding by contract still persists. By this system the weeder undertakes to keep an area of land properly weeded for a fixed sum. The increasing use of more modern methods seems likely to bring this traditional practice to an end.

Hand weeding was and still is combined with the operation of breaking the banks between the rows of young cane and, at a later stage, of moulding the cane by which the ridge between the rows was levelled. This work is largely done by animal drawn light implements and by mechanical power. In land where cane is grown under natural rainfall it seems likely that manual and animal power will continue to be used unless the modern system of control by weedicides comes into general use. Hoeing and inter-row cultivation have the effect of disturbing the soil, destroying newly germinated weeds and removing those in later stages of growth with greater or less efficiency.

Flame cultivation has been introduced during recent years and is now standard practice on some plantations though it is likely to give place to the more convenient and less risky method involving the use of chemical weed destroying substances. Flame cultivation will effectively control weeds in the cane rows and thus solves the line weeding problem. It must, however, be used with extreme care, as there is danger of the intense heat damaging the young cane if applied for a longer time than the instant necessary to deal satisfactorily with the weeds.


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Inorganic chemicals, such as sodium chlorate, have been used for many years for weed destruction in the field. The discovery of the group of plant growth regulating substances, or hormones, combined with that of the weedicidal effect of aromatic oils has provided a new and effective weapon for the planter's attack on varied problems in the cane fields and adjoining areas.

Success has attended the investigation of biological methods of control of certain weeds by the use of insects, which feed specifically on certain types of unwanted plant. The subject is of intriguing interest, and one major success in a territory invariably leads to an intensification of research on the possibilities of similar methods of control for other weeds, and the raising of the hopes of the planter for an inexpensive and effective agent which will cope with one of his major problems. Wherever insects do exercise an effect upon the intensity and spread of a particular weed, the result is of use to the planter only in areas which may be sources of the re-infestation of his planted fields. Biological control in this manner is a slow process, and not one upon which the planter can possibly rely for the suppression or eradication of weeds. In any event there are comparatively very few of this class of plant which are controlled by insects, and even if one or two were kept in subjection by such natural agencies in the cane fields, there would be numerous others still needing attention by standard methods. Biological control of weeds therefore is of passing scientific interest only to the sugar-cane planter. The position is different with certain pests of the sugar-cane, a subject which is discussed in Chapter 6.

General Properties of Weed Killers Chemical weed killers or weedicides include inorganic chemicals

such as sodium chlorate, compounds of arsenic, oils which act as poisons, and organic compounds such as 2, 4-D (2, 4-Dichloro-phenoxyacetic acid) which are similar in their action to plant hormones. The effect of all of them may be said to be that of a poison, but the hormone-like substances destroy weeds by stimulating irregular development, thus completely upsetting the normal growth process and causing the death of the plant. The inorganic weed killers are objectionable and dangerous to human beings. Sodium chlorate is a powerful supporter of combustion- Dry


clothing, boots, and any combustible material are readily ignited by friction in the presence of the chemical, and burn fiercely. The use of a solution of sodium chlorate alone is therefore highly dangerous, because of the great risk of setting fire to the clothing of operators when the water has evaporated from wetted areas leaving the chlorate in a dry condition spread through the clothes, which will then burst into flame very easily. A suitable proportion of common salt or calcium chloride will render sodium chlorate safe to use. Arsenical weed killers are intensely poisonous to human beings and animals. Protective clothing is essential for operators using them. Though formerly extensively employed on sugar plantations in Hawaii and Puerto Rico, they have been largely replaced by selective and contact herbicides. The weedicidal action of hydrocarbon oils of the paraffin series appears to depend partly on their suffocating effect and the disturbance of the water and air relationships of the plant. The destruction of weed patches in foot paths and roadways by used motor crank-case oil has been common practice for many years. In the campaign against Panama disease of bananas in the West Indies, a light distillate oil proved the best and cheapest means of destroying banana plants which had been cut down to ground level, and of suppressing vegetative growth near them. The aromatic hydrocarbon oils are even more potent destructive agents as contact herbicides, especially when fortified by the admixture of other weedicidal substances. The power of these mixtures to destroy all foliage with which they come in contact makes it essential to use them with the greatest care. Weed killers differ in their action upon the various plants to which they are applied. Some are selective, killing certain weeds and leaving other weeds and plants unharmed, while the contact herbicides are capable of killing all plants.

Need for Local Investigation The development of a range of chemicals which can act as

highly efficient weedicides has placed a new and effective weapon at the disposal of the planter. It is not possible, however, to formulate mixtures and methods suited for general use under all circumstances. Each area offers its own set of conditions which must be carefully studied before embarking upon chemical weed


control as standard plantation practice. Investigations should commence with a weed survey to determine the kinds of weeds, including grasses, which are found in the cane land and adjoining areas. The relative degrees and periods of infestation by them should be observed. Small-scale trials of various formulae applied in different ways and at different times should be conducted. Mixtures found to give satisfactory results should then be used on a larger scale in comparative experiments so planned as to provide information in regard to the cost, degree of control, frequency of treatment and effect upon the cane. Such work must be conducted in a similar manner to other applied research, with experiments of proper design and layout, carried out over a sufficient range of conditions. It has been found in practice that the introduction of a particular method of weed control by herbicides as a result of work of this nature is not always the final answer. The use of herbicides changes the plant population picture, both in regard to varieties and densities of the weeds it is desired to destroy. Some will be found to display more resistance to the treatment than others, so that the degree of infestation by them may increase. In extreme cases this can produce a more serious weed problem unless counter measures are promptly taken. Weeds not formerly seen in the cane land, possibly because their growth was prevented by those commonly occurring, may appear. New formulae and technique will therefore be required from time to time in consequence of continued study and observation. The extent of re-infestation and the sources from which it may come will need attention. Field traces, intervals, open banks, railway tracks, headlands, and adjoining land not planted with cane will thus require suitable treatment for the suppression of weeds which may gain access to the cane fields.

The effectiveness of the various compounds and mixtures containing them depends to some extent on the stage of development of the weeds they are intended to destroy. The rate and frequency of application of weedicides will vary with weather conditions. Rainfall, its intensity, duration, and amount, will affect chemical weed control by stimulating weed growth, while it may reduce the destructive power of the applied weedicide by washing part of it off the plant into the soil, or make it impossible to give an application at a time when it is needed. Treatment is best carried out in

N


dry weather, and once the formulae and mode of operation have been settled by carefully conducted trials, it is essential to conduct the work as standard plantation practice using trained operatives under constant supervision.

Selective Herbicides Compounds of this class when used in certain concentrations

kill some plants and have little or no effect upon others. The best known is 2, 4-D (2, 4-Dichlorophenoxyacetic acid) which is available in various forms with a wide range in actual content of the acid itself. These may be grouped into :—

(a) the acids, usually solids, (b) the esters, such as butyl ester, marketed in liquid form with

an emulsifier, (c) the amine salts, (d) the sodium and ammonium salts.

Though the rate and extent of action on affected plants varies, the comparative efficiency of different formulations is proportional to the amount of 2, 4-D acid present in them. The content of 2, 4-D acid in the various compounds is shown in table.

2, 4-D in various proportions, unmixed with contact herbicides is most effective against broad leafed weeds, but exercises little or no action on true grasses in ordinary concentrations. Nut grass—


Cyperus rotundus—(not a member of the grass family) is a widespread objectionable weed very difficult to eradicate in cane fields. While repeated applications of 2, 4-D will destroy it, the cost of such treatment may be found too expensive. Other plants out of place which are regarded as weeds in the cane field, such as varieties of crotalaria, and the sensitive plant Mimosa pudica, are similarly resistant to the action of 2, 4-D. Various preparations containing 2, 4-D as the principal constituent, with other herbicides, are marketed and are more widely useful than 2, 4-D in any of the four forms mentioned above.

Contact Herbicides These may be regarded as the chief killers of nearly all unwanted

growth, including true grasses. Various kinds of oil are highly potent, and become even more so when fortified. Pentachloro-phenol is a very effective fortifier or activator, and is readily dissolved in aromatic petroleum oils. One advantage of the aromatic oils is that they spread uniformly on leaf surfaces and are not easily removed by rain. The oil thus exercises a poisonous effect which becomes remarkably increased by small quantities of dissolved chlorinated phenols. They become so intensely active as weedicides that it is necessary to use them in emulsified form with water. Various emulsifying agents are marketed, and it is possible for the planter either to obtain by purchase mixtures best suited to his requirements, or to prepare them himself. Whatever mixture is used it is essential that the complete wetting of the leaves is achieved. It is therefore important that a suitable wetting agent should be used. The quality of the water may effect the choice of wetting agent. A very hard water or water containing an excessive quantity of salts is objectionable.

Field Practice A method of weed control by herbicides which has found great

favour is the application of a suitable preparation of 2, 4-D to the bare surface of the land at or shortly after the time at which the cane is planted, known as pre-emergence treatment. This checks all weed growth and gives satisfactory control for a period extending to as much as 10 weeks under favourable circumstances. The principles of successful weed control, the destruction of weeds


before the cane is planted, which apply to other methods have equal force with this system. The land should therefore have received light surface treatment with discs or other implements shortly before the cane is put in so that at the time the herbicide is sprayed on, no weeds are showing, and the surface is free from clods and lumps. The cane is enabled to germinate and sprout in the almost complete absence of any competing growth. 6 to 8 weeks after the pre-emergence application of weedicide a further application is necessary using a mixture which may be the same as or different from the former one. The risk has been recognized of building up a population of resistant weeds by the use of only one preparation so that it appears desirable to have different mixtures, each of which alone is capable of giving a satisfactory result. The selective effect of 2, 4-D discussed above supports this view. Its use alone in any one of its available forms could lead to the appearance of a dense growth of grasses and resistant weeds for which other means of control would have to be quickly devised. The pre-emergence treatment is applied to the whole surface of the planted field. Subsequent applications of weedicide will be needed in the cane rows, and if inter-row cultivation is not practised, between them as well. Once the young shoots have appeared above ground, the type of material and its method of application must be such that the cane is not damaged and the weeds are suppressed. It may, therefore, be necessary to use a selective herbicide in the rows and a general contact herbicide between them.

Method of Application

The pre-emergence treatment can be given by the use of tractor-hauled spraying machines with suitable boom and jets so arranged as to give even distribution at the desired rate of application. Though similar machines could be used for selective herbicides in the young growing cane, they are not suitable for the general contact material because of the high risk of damage to the crop. Knapsack sprayers are therefore generally used, and special types have been designed for the purpose. Contact herbicides are applied when the weeds are very young, but not until the cane has reached a height of 15 in. or more at which stage it is able to recover from any slight set-back brought about by small quantities of the

>i


weed killer. Every precaution is taken to prevent the material from falling on the heart leaves of the cane.

The rate of application for pre-emergence spraying in terms of 2, 4-D acid varies according to local conditions, ranging from 2 lb. per acre up to as much as 4 lb. The form in which the 2, 4-D is used is similarly decided by its efficiency which can only be decided by trial under the prevailing conditions. It has been observed that excessive dosage adversely affects the germination of the cane. One of the great drawbacks to extensive spraying for any purpose under older methods was the large volumes of water needed for the preparation of the spray mixture and the application of the active material to the land or the plants to be treated. The former high volume spraying has been replaced by low volume working using improved nozzles which deliver a fan-shaped spray giving uniform coverage. One man using a knapsack sprayer can now complete 2 acres in an 8-hr. working day under average conditions, nearly three times as much as with high volume work, when about one-fifth of the time was occupied in recharging the sprayers. The volume of liquid used need not exceed about 20 gal. per acre, and with a standard type of knapsack sprayer, recharging is only necessary four or five times in a working day. It is not advisable to use higher concentrations of contact herbicides and lower rates of application, as much damage can be caused to young cane.

Knapsack Sprayers A satisfactory knapsack sprayer is of about 4 imp. gal. capacity,

fitted with a diaphragm pump working at a pressure up to 40 p.s.i. Oil resisting synthetic rubber diaphragms can be used. The spray rod is fitted with a cross piece carrying low volume type nozzles which give fan-shaped discharges which converge at the level of the plants being treated, when the rod is held at an angle of 45 ° to the ground. Lower capacity knapsack machines in which the air pressure is retained when the liquid contents are sprayed, with working pressures up to 175 p.s.i. are obtainable. Cylindrical pneumatic knapsack sprayers which are recharged with air at intervals either by a pressure pump which forms part of the sprayer, or by a compressor used when refilling with spray mixture takes place, leave the operator completely free to direct control the spraying without having his attention diverted by pumping as


he moves over the field. Comparative weights, uncharged, of standard makes of knapsack sprayer are:—

Knapsack Sprayers, diaphragm pump type : Capacity 3¼ gal,; weight complete 14 lb to 15^ lb.

Pneumatic Knapsack Sprayers, self-contained pump : Capacity 2¼ gal., 175 p.s.i. 23½ lb. Capacity 3 gal., 175 p.s.i. 26 lb. Capacity 3 gal., no p.s.i. 21 lb.

Spraying Programme An example of plantation practice which has been developed

from extensive preliminary inquiries is as follows :— (a) Pre-emergence spraying immediately after planting, using

the Ammonium Salt of 2, 4-D at the rate of 2 to 4 lb., 2, 4-D Acid in 20 to 30 gal. of water, applied by a tractor-drawn boom sprayer with nozzles suited to the volume rate of distribution.

(b) Six weeks later—the first contact spraying, using a contact herbicide formulation applied by manual operators with knapsack sprayers, the cane being 15 in. or more high.

(c) Four weeks later—the second contact spraying—when the cane is not less than 24 in. high.

(d) Four weeks after (c), the third contact spraying.

The intervals between successive treatments may vary somewhat, and the third contact spraying is not always necessary. The effectiveness of contact weedkillers depends on applying them when the weeds are very young.

Contact Herbicide Mixtures Standard formulae capable of variation to meet local conditions

are quoted below :— (a) Sodium pentachlorophenate 8 lb.

Aluminium sulphate 4 lb. Emulsifier 4 to 5 lb. Diesel oil 2 gal. (Amer.) Water 100 gal. (Amer.) Pentachlorophenol may be used, but as it is not easily soluble, it must be dissolved in 1gal. of aromatic oil with


the emulsifier, and then mixed with the diesel oil. Only 2 to 4 lb. pentachlorophenol are required for each 100 gal. of the emulsion. Various types of oil can replace the diesel oil, among which are Texas Oil (aromatic), Eno Standard Weedkillers, and Shell Weedkillers. The pentachlorophenol or its sodium salt may be substituted by Di-nitro-cresol, or one of the Di-nitro-phenols.

(b) Pentachlorophenol 2 lb. Emulsifier 2 lb. Diesel Oil 4 gal. (Amer.) Water 40 gal. (Amer.)

Louisiana The problem of control of grasses in cane land which are not

affected by 2, 4-D has been under investigation. The chemical offering the greatest promise so far is trichloracetic acid which has already been successfully used on a commercial scale in the form of its sodium salt. When applied at the rate of 10 to 20 lb. acid equivalent per acre, before the seedlings of Johnson grass appear, it has been found to give good control in Louisiana when the soil is moist and the surface firm.

Control of seedlings with 2, 4-D at 2 lb. acid equivalent per acre followed by two flame treatments at intervals of 1 week have proved effective. Pentachlorophenol with 2 lb. per acre 2, 4-D in oil applied at the rate of 6 gal. per acre gave moderate control, as also did sodium trichloracetate at 20 to 30 lb. per acre. Individual plants which have survived other treatment may be killed by thorough wetting with a spray containing 2 lb. sodium chlorate and 1 lb. trichloracetic acid per gal. Control on ditch banks and headlands is costly, 600 lb. per acre of sodium chlorate being the minimum application, which is preferably given in the spring and summer, and is most effective when the Johnson grass is flowering.

Hawaii Weed Control From the Air

Efficiency of pre-emergent spraying has reduced the amount of 2, 4-D required to 1 to 1½ lb. per acre in 7 to 10 gal. of water. Sodium pentachlorophenate at 10 lb. per acre in water; or diesel oil emulsion containing sodium pentachlorophenate are satisfactory


for plants in Hawaii. Ratoons are treated with 3 to 4 lb. 2, 4-D per acre, and a combined contact and pre-emergent spray of 2, 4-D with diesel oil. Low volume spraying using 2½ gal. per acre of 2, 4-D mixture and 40 gal. T.C.A. gave good control.

During recent years aircraft have come into the service of agriculture for various purposes including the control of weeds. Some of the large cane sugar companies use fixed and rotating wing machines for personal transport and various plantation purposes including inspection and rat control. A helicopter suitably fitted with compressed air bottles, spray fluid containers and spray booms can effectively treat crops or bare land, flying a few feet above the ground, at a working rate of 60 to 80 acres an hr., using low volume nozzles with an application at the rate of 2 to 3 gal. per acre. Although widely used for pest and weed control in many other crops, the application of this method to pre-emergence weed control for sugar-cane has not yet been developed. The possibilities of other plantation work for suitable aircraft are apparent, and there should be no difficulty in keeping a machine in profitable operation for a sufficient number of flying hours each year for various purposes such as weed control, poison baiting for rats, general inspection work, and fast travel within a territory. The ground services required for a rotating wing machine used for spraying include special tank wagons for spray liquid, an air compressor for recharging the steel bottles, engine fuel and oil, all of which can be quickly loaded into the aircraft at numerous convenient points near to alighting places, which are determined in advance. Fixed wing machines, which are not so suitable for general agricultural spraying, must have landing strips at different places, or return to base each time recharging with fuel and material is required. Advantages of the helicopter are its ability to hover or move in the air at varying speeds a few feet above the ground, and to land and take off in a very small area. The down-wash of air caused by the rotor brings about uniform spray coverage and droplet size, so that 90% of the spray is effectively applied.

Introductions of New Weeds Apart from what may be termed the differential control of the

weed population exercised by one or several of the methods dis-


cussed, which can result in some weeds becoming more dominant and troublesome than when they were in competition with those brought under subjection, there is a constant danger of new weeds being brought in. Stray introductions can be made in straw packing, by road vehicles, in soil attached to parts of implements, by birds and animals, and in various odd and unnoticeable ways. The balance of plant growth generally in the lands surrounding the cane areas may be altered in time by new infestations of plants foreign to the district. The planter should be alert to notice any new plants including weeds which may appear on and near road sides, in land contiguous to building sites and other places where adventitious introductions may take root. The planting of suitable barriers, which may take the form of hedges, in convenient places, will help to check the spread of weeds from infested spots, and is a useful way of assisting the general control of cultivated land. The desirability of reserving acres of woodland, bush and commons within the cane areas has been commended for other reasons, and may appear to conflict with the necessity for weed control in the fields. The use of plant barriers, and close attention to the lands bounding on such wild reserves will provide satisfactory hindrances to the spread of weeds from them.

Cover Crops and Flood Fallowing Land which is left in open fallow after the reaping of the last

ratoon and before the planting of the next crop of cane may soon become heavily re-infested with weeds, particularly under rainy conditions, and will provide a centre of re-infection for surrounding fields. Such land will require more effort to bring it under control when replanting is done. It is in any case undesirable to leave any land unprotected for longer than is absolutely necessary, and the development of dense growths of miscellaneous weeds which appears is an additional reason for some form of protective fallowing. A method which suppresses weeds and offers the associated advantage of improving the soil in both texture and fertility is the planting of a suitable leguminous cover crop which is subsequently ploughed in. The cultivation of the land just before the cover crop is planted includes a weeding operation, and the quick growing legume gets away faster than most weeds


and hinders their development. The practice of flood fallowing in British Guiana by which the fields are covered with water to a depth of 1 ft. above the highest part of the beds for about 6 months kills most of the weeds, and confers other benefits similar to those brought about by cover crops.

Precautions The range of new weedicidal materials has provided the planter

with effective methods of weed control, which in some conditions may involve interference with agencies beneficial to the cane. In Brazil the use of 2, 4-D is believed to have affected the parasites of the moth borer, Diatraea saccharalis, thus increasing the damage to the cane by that insect. Other parallel cases have occurred in places where some of the new insecticides, B.H.C. and D.D.T. are used for the control of certain pests of the cane. It is, therefore, important to maintain continuous and careful observation of the crop, its enemies, and any changes in their effects upon it. Indeed this procedure is essential under any circumstances, and should normally be a routine of plantation control, intensified when new measures to cope with an old problem are introduced.

When applying sprays of any description care must be taken to prevent them from affecting land or plants other than those to which they are specifically directed. For ground work, still or very gently moving air provide suitable conditions, and aerial application should only be done when there is no wind. The reasons are that maximum effect is only obtained by the proper dose being applied with uniform coverage to the soil surface or the plant, and this cannot occur except in the calmest weather. Drift of spray by air movement causes irregular dispersal, poor coverage, and loss of much of the spray particularly when low volume work is being done as then the individual particles of spray are extremely small.

CHAPTER 12

HARVESTING THE CANE

General Considerations Reaping, loading and transport which may be included under

general term "harvesting," have been discussed briefly in Chapter 8. The operations concerned are the culmination of the planter's work. The milling or factory company is vitally interested, whether the cane has been produced by its own organization, or is sold to it by an independent grower. The cane having reached the stage of maturity should be supplied in a steady and carefully regulated flow to the mill. Perhaps this is more easily arranged when fields and factory are under unified control, but there is no inherent difficulty in bringing it about under other conditions so long as all parties bend their energies to the work in hand and act in co-ordination. The value of the crop depends so much upon careful attention to detail at the time of harvest that it should be helpful to examine the matter closely.

Maturity of the Cane The first essential is to ensure that the cane is ripe. Mention

has been made in Chapter 9 of the planning of planting and cutting with a view to systematized reaping of mature cane. This, however, will not always result in fields being cut in the order which dates of planting, varieties planted, and time of previous reaping in the case of ratoon crops, would indicate, though decisions regarding the sequence of reaping of fields are assisted. Determination of ripeness is a combination of experience, visual observation, a knowledge of the recent history of the field from the time of planting for the existing crop cycle, and testing of samples of cane. Weather conditions enter into the planter's judgment; and where irrigation is practised, water is withheld for about 6 weeks prior to the proposed time of reaping.

Testing for Ripeness The testing of the cane is carried out in various ways. Sampling

of whole canes taken at random through a field may be done; a 193


selected stool completely cut; portions can be punched out by a simple tool from different parts of a number of standing canes ; and the juice from standing canes can be examined in the field by a hand refractometer. With the first two methods, the cane is freed from trash, tops and any dirt, crushed in a small mill, and the juice analyzed. A more elaborate procedure is also to examine the bagasse. The mill setting is constant for samples from all fields so that comparative figures are obtained. Sampling is often begun 4 to 6 weeks before the proposed start of milling, and continued at intervals of about 2 weeks until a decision regarding reaping of the particular field has been taken. Objections to these methods are that a considerable quantity of cane is used ; that the accuracy of sampling is not greatly improved, or in other words, the samples may or may not represent the field of cane as a whole ; and that the trouble involved is too great.

The core-punch sampling method meets these objections. Based on careful study at Clewiston in the Florida Everglades, it has been shown to give a close approximation of the juice characters of a field of cane which satisfactorily indicate whether cane is ripe or not, without destroying the cane or requiring any great expenditure of effort. The sampling tools required are a punch which cuts a cylindrical core transversely from the cane, and a portable hydraulic press made from a hydraulic automobile jack. By this method uniform extraction of juice samples is achieved, these being used for making comparisons of purity, sucrose in the juice, and estimated mill yield of 960 sugar.

Examination of juice in the field is conducted by using a hand refractometer graduated to give readings in degrees Brix. The cane is sampled by taking a small quantity of juice from the upper and lower portions of standing cane in the field, avoiding the topmost joints. This may be done by cutting a small wedge-shaped portion out, which can be squeezed by any convenient manner so that a little juice drops on to the prism face of the instrument. The reading is then taken, the temperature noted, the prism opened and cleaned, and the procedure repeated. The readings for the top and bottom of each cane examined are recorded for a number of canes chosen at random through the field.

HARVESTING THE CANE 195

Core-Punch Method The core-punch method of field sampling developed by B. A.

Bourne in Florida has been successfully used in field experimental work, and the testing of commercial cane for maturity for some 20 years during which period it has been improved. The equip-ment required is:—

(1) A sharp tool-steel core-punch 2½ in. long and f in. inside diameter, connected to a closed brass cylinder 5½ in. long and 2 in. diameter, which is fitted with a screw cap. The cylinder serves as a handle and a container for the cores, the construction being such as to prevent evaporation of moisture from them.

(2) The juice is expressed in the field with a portable hydraulic press fitted with a gauge enabling a uniform pressure of 1,131 p.s.i. to be exerted on successive samples. The press is adapted from a standard type of motor-car jack of 7 tons capacity with a piston cross section of 2.0739 sq. in. The plunger is at the top and is stationary, being connected to the base by a vertical support on each side. The press surface is 5½ sq. in. in area. The core samples are placed in a removable inner cup which has an open bottom. This is surrounded by a watertight outer core sample cup which delivers the expressed juice to a jar suspended on the delivery spout. The outer cup has a flanged steel base which fits into a groove in the top of the hydraulic jack and is removable.

(3) A miniature Brix hydrometer with thermometer which requires only 60 mls. of raw juice to enable accurate and rapid Brix determinations to be made.

(4) A Zeiss hand refractometer, also used for the determination of Brix.

Sampling of a field is conducted by taking approximately 75 separate mid-stalk cores from each of the four sides of a field some distance inwards from the field edges. With fields of 40 or 80 acres in extent the distance from the edge is approximately 75 ft. The juice of each 75 stalk sample is immediately expressed in the field and preserved in a closed glass jar with a small quantity of mercuric chloride, the sugar analysis being completed


within a few hours. It was found that no deterioration of juices occurred after standing in the jars for seven hours at ordinary field temperatures, when expressed and preserved in that way. The calculations for the yield of 960 sugar are based on tables using the mill factors obtained from the Clewiston Factory.

A similar method used in Java is applied over a period of about 75 days at intervals of 15 days, being discontinued when the Brix, polarization and purity no longer show increases.

This work, whichever method is used, is best carried out by the factory chemist and his staff, though the hand-refractometer method is suitable for field operators as no laboratory is needed, the only instrument being the small refractometer, of which several different makes are readily available.

Basis of Cane Valuation Modern cane valuation is based on its sucrose content at the

time of delivery to the mill. Methods of determining the price payable to the planter vary considerably in detail, but the founda-tion of all is the market price of cane sugar, and the proportion of it present in the cane. Thus, quality and tonnage are the com-bined factors which regulate the farmer's share of the market value of the sugar in respect of his cane deliveries. It has not been an easy matter to convince all planters that cane quality is of prime importance, and there are still places where the growers judge their planting success by the weight of cane, and resist proposals that payments must be based on its quality in terms of sugar. Once seized of the true significance of cane quality, the planter endea-vours to get all his fields cut when they are in peak condition, and practical difficulties with the factory arise because the cropping period is limited and uniform flow of cane from all sources to the mill must be regulated.

Co-operation with Millers The rate of progress of harvesting operations is governed by the

daily sustained grinding or crushing capacity of the mill. The closest co-operation between the suppliers of cane and the staff of the mill is vital if losses of cane and sugar are to be reduced to a minimum, and confusion avoided. The object of the miller is to keep the factory working to its highest throughput consistent with


efficiency, on fresh cane of the best possible quality. These ideals are rarely achieved in practice except for short periods, largely because of delay and irregularity in the movements of the cane from the fields. In discussing these problems it is necessary to keep well in mind the paramount importance of efficient pro-cessing of cane, which is vital to the miller and to the planter alike. The planter's close contacts with the milling organization should be maintained immediately prior to, and during the " crop " period. He will have been requested at various times to provide estimates of the weight of cane expected to be delivered. The allocations of quantities of cane to be delivered daily to the mill will be made on the basis of returns from all sources of supply shortly before the commencement of crushing. As crop proceeds new estimates are prepared and revisions made of the daily cane delivery allocations. These arrangements apply to cane grown on land under the same control as that of the factory, and to planters who deliver their cane to the same factory. Adjustments are often made to the daily quantities allotted to the latter for special reasons such as avoidance of fractional loads for transport vehicles.

Railway Control A crop delivery scheme of this nature works well when the

railway transport is efficiently planned and operated, conditions which are difficult to meet unless it is owned and controlled by the factory company. Even then the movement of cane from the fields in fresh condition rarely approaches the ideal, which may be described as the sustained and regular flow from field to mill so that all cane is ground within 24 hrs. of being cut. When railway delivery is combined with road transport direct to the factory, the difficulties increase, but even so are much less than those entailed by railway transport not under the control of the factory staff. Actual quantities received from the various points differ considerably from the daily allocations for various reasons. Overages and shortages from different sections can easily be made up by adjustments elsewhere when all operations are under unified control which provides for the necessary flexibility of working. In cases where the whole or a high proportion comes from independent suppliers it is by no means an easy matter to effect such changes quickly. The organization and regulation of


cane deliveries from numerous places to a large central factory demands the services of a special officer with a competent staff in constant touch with all parts of the transport system. His orders and instructions based on information supplied regarding such matters as variation in grinding rate, quantities of cane in move-ment to the factory and awaiting transport, empty and loaded vehicles at different points, and all related matters must be put into effect promptly if confusion is to be avoided. Unforeseen factory stoppages call for action in relation to the estimated time needed to effect repairs or adjustments. Provision must be made to cope with the special conditions which arise from week-end and holiday shut-downs. Communication by telephone with all rail-way loading points, farm offices, the cane receiving station at the factory and field and factory executive offices is necessary.

These contacts must continue through to the supervisory staff in charge of reaping operations in the fields. A continuous record should be kept in respect of the whole rail or tramway system so that at any time the control office is aware of the numbers of cars, both empty and loaded at any point, those in transit to the factory with times of dispatch from loading stations, empty cars on the way out, and all matters relating to the railway operation. All movements should take place only with the authority of the control staff, except within the limits of a siding when cars are being loaded. A convenient practice is to review the cane delivery position at the close of each 24-hr. grinding period, ending say, at 6 a.m. This will include the quantity of cane ground by the mill during the previous period, the estimated tonnage delivered and loaded in railway cars in readiness for hauling to the mill, and the quantity required to maintain grinding for the succeeding period with adequate carry-over into the next one. These figures should be available for each loading point on the railway, supplemented by those referring to quantities received by road. It will quickly be seen whether any change is necessary for the daily quota already notified. Should that be the case information is at once sent out to the fields and action taken.

Regulation of Reaping Whatever the method of control may be, the reaping should be

most carefully regulated and controlled by the planter's own


organization in accordance with the requirements of the factory, of which he is kept advised. The cane begins to deteriorate from the moment it is cut, and though the perceptible effect on mill process and recovery is negligible during the first 24 hrs., cane quality declines rapidly after that, burnt cane being affected to a much greater extent than cane cut " green." When all harvesting is mechanized the planter experiences little difficulty in getting the cane off the fields and on its way to the mill. Delays often happen after he has lost control of the movement of the cane, but their effect over a crop can be minimized by an efficient system on the lines mentioned which is operated by the milling organization, and by full co-operation by the planter with it. Manual reaping is less easy to regulate. The cane cutters soon develop a rate of cutting suited to their own convenience and the field conditions in which they work. They like to see the cane moving from the field quickly, and delays in field transport are soon succeeded by a slowing of the cutting. On the other hand they may work faster or for a longer time to cope with occasional shortages. Much depends on the method of payment for the cane cut. When teams or gangs of cutters work together and share the proceeds the field control is simplified as the supervisor deals only with the head man of the team, who is selected by the members of it (Fig. 23). If cutters are paid on a basis of weight of cane reaped, the usual practice in many places, there is an incentive to cut more cane than may be immediately wanted. This happens frequently with men working individually and in pairs, with the result that some of the cane has to remain for a longer time than normal before it reaches the mill. Estimation of the weight of cane cut in the field is subject to considerable error, though it is surprising how close an experi-enced field man can be to the figures ascertained by weighing.

It is almost inevitable that cane in the field, cut and lying on the ground, is in excess of the quantity actually needed to carry over the night grinding to the time that the succeeding daylight move-ment of cane reaches the factory. Field men dislike being blamed in the mill reports for stoppages of grinding, and will go almost to any length to avoid giving cause for the use of the term " out of cane" in the daily records. This causes the field to keep up deliveries in such a manner that the railway or road transport system is more likely to be heavily congested than the factory is


to get short of cane. This is one of several matters related to har-vesting which requires close supervision as it may easily lead to quantities of cane becoming stale because of prolonged delay between reaping and crushing. Trouble is caused in the clarifica-tion plant and boiling house, with the result that the factory reporting staff record another objectionable term, " stale cane."

Stale Cane, and Railway Delays Unfortunately stale cane is a common, almost a standard con-

dition when dual transport is involved, such as a railway inde-pendent of the planter on the one hand and the factory on the other, which receives cane from the former for delivery to the mill. In such circumstances it is not unusual for a week or even more to elapse between reaping and grinding. Sucrose recovery becomes difficult and more costly, while both planter and miller experience loss. It is not always an easy matter to correct such conditions. A public railway company must maintain services for all kinds of traffic, and though rolling stock may be allocated in adequate amount for cane transport, cars cannot always be moved promptly, and are in any event subject to delays for various reasons, which would not occur on a plantation railway or tram-way. When the transport system is under the direct control of the milling company, cane traffic is the only activity for practical purposes during the crop period and all energies are bent to keep it moving. Under such conditions it is not always necessary to await a full train load before moving off to the mill; indeed it is often expedient to convey a few loaded cars in order to keep the mill supplied or to relieve congestion. With a public railway, cars are usually only moved in full trains, being shunted into sidings and held up there if the system becomes locally congested. A further difficulty arises in some places because the public railway organization will not allow any but its own employees to move cars. Thus loaded cars may sometimes wait for long periods in sidings near to the mill receiving point because of lack of an engine to move them, or of staff to do the shunting.

These difficulties have been overcome in some places by a mutual arrangement with proper safeguards whereby the factory organization controls all movements within a prescribed area, which may be the sidings in the mill yard, or the branch track

HARVESTING THE CANE 2 0 r

which leads to the mill, from the main line, including the factory sidings. It is usual for the milling company to have its own loco-motives for such purposes.

Keep the Cane Moving Efficiency of transport depends upon co-ordination of all stages

from the field to the mill so that cane is not held up for a longer time than is necessary to complete without delay the particular operations at any point. Put in another way, transport should be kept moving except for the times required for loading and dis-charge, both of which should be performed in the least time con-sistent with safe and efficient working. Idle time during actual working periods should be reduced to a minimum for all units employed. It will be found helpful to make accurate observations of elapsed times for all operations involved in the movement of cane, differentiating between the times actually required to com-plete each job, and times occupied by waiting. This should be done at a number of different points, and at varying times. Analysis of the data will disclose interesting information of great use in plan-ning and control. It will be found that certain groups of operatives are consistently better workers than others ; and that the amount of lost and idle time varies remarkably. Improvements will be suggested by these comparisons and by persistent effort the weight of cane per vehicle for each working period will be progressively increased until a satisfactory maximum is reached. It may be found necessary to improve the equipment at certain points, to increase supervision, to regulate the number of vehicles in trains, or to provide additional incentives to operators.

Supervision The reaping of the cane whether done mechanically or by hand

needs supervision. When payment is made on weight cut, manual workers will naturally adopt the easiest way to complete their day's job, and cane will often be severed above ground level leaving a considerable amount of millable uncut stubs in the field. This causes loss to the planter because of lower yields, and adversely effects the sprouting of the succeeding ratoon crop. The actual affect on yield may easily amount to 2% from this cause alone, which in some places represents one quarter of the cost of reaping.


Careless topping may be another source of loss. If the cane is topped too high, the amount of immature top remaining adds a little to the weight, but reduces the average sucrose content. The removal of too much has the contrary effect.

" T r a s h y " a n d D i r t y C a n e

The vexed question of " trashy" cane is often the cause of differ-ences between the planter and the milling company. The two extremes of the matter occur in the West Indies and Hawaii, though there are local differences in those areas. In the former, where manual reaping only is practised, the cane is topped and stripped of trash in the field by the cutter. Burning prior to reaping is done in Trinidad and British Guiana, and cutters there have only the charred top to remove. In Jamaica the legal definition of reaped cane delivered for sale to a factory refers to cane of the usual quality and varieties, clean, free from trash dirt and other foreign matter, and suitable for milling. Generally throughout the West Indies the cane delivered to the mills is remarkably clean. This is due to custom and to constant supervision. Attention is promptly called to trashy cane and every endeavour made to ensure that the cane cutters do their work properly.

The labour difficulties which were experienced in Hawaii a few years ago made it necessary to mechanize rapidly all possible field operations, including reaping. Much improvisation had to be used, particularly in harvesting operations as no specially designed reaping machines had been devised. Dozers and grabs were em-ployed to push over or pull up the cane, which was loaded mechanically into transport vehicles. These methods, which still continue, result in a mixture of cane with adhering trash and tops, earth, stones, cane roots and other miscellaneous foreign matter, being delivered to the factories, which are equipped with special cleaning plant for separating the rubbish before the cane enters the mill. The amount of soil actually removed from fields in this manner is so great that it is transported and put back on the land.

Intermediate between these extremes are the practices of other countries where the removal of trash and tops is not so carefully carried out as in Jamaica for example, but where the methods used avoid the cane becoming mixed with the other objectionable foreign


matter as in Hawaii. The principal effects of " dirty " cane, which for the present consideration includes trash and tops, are to in-crease the cost and reduce the efficiency of mill recovery. The total weight of the cane is increased in proportion to the amount of the trash and tops, but the sucrose is not augmented though it becomes more difficult to extract. The value of the cane is im-paired, and it is a debatable point whether the planter derives any advantage from the neglect to supply the cleanest possible cane except when cane is cheaply reaped by mechanical means.

Mechanical reaping is discussed in Chapter 14 but there is a point which calls for further consideration in relation to observa-tions on the " trashiness " of cane, and its effect on recovery. One of the great difficulties of mechanized reaping is the removal of the tops. Moreover, machines do not work well in standing cane with adhering trash, so that burning is practised. If the cane were cut whole, with no attempt at cleaning in the field, it might be delivered to the factory in that condition; and there put through a preliminary process to remove trash and tops. This could be done in the manner suggested on p. 290, by cutting up the cane into pieces a few inches long and separating the trash and tops by air blast. The cane pieces would immediately pass to the first stage of the milling process, with no deterioration of quality. Further reflections on this proposal from the milling viewpoint are beyond the scope of the present work, but there would ob-viously be important effects to the planter. Reaping would be simplified, loading, and transport might be a little more difficult and expensive, and some changes might be necessary in the assess-ment of the value of the cane, though these would not be great if payment were made on a basis of sucrose content of the whole cane, as in Natal. The rate of deterioration of the cane would be reduced. There appears no reason to suppose that the gross amount received by the grower would be in any way reduced, while his net return might possibly be increased. Cane tops usually cut from ripe cane for planting would have to be got from cane specially topped, or replaced by setts from immature standing cane.

Identification of Load The identification system for reaped cane which applies to all

stages from field to mill is an important detail. Methods vary


with differences in reaping systems and transport practice. Cane reaped manually by cutters working individually or in pairs, with a two-stage transport system using field carts and estate railway, with payment for all labour on a tonnage basis offers one example. With this system the operations of cutting, loading, transporting to the railway receiving point, and transferring by hoist to rail cars are separate and distinct, being carred out by different work-people paid at various rates. Weighing, which occurs at the railway receiving point is done by men paid at daily or weekly rates. The identity of the cutters and loaders with the cane they deal with must be maintained until the weights are ascertained. To effect this, all cane cut by the one, or more men when they work in partnership, is loaded by the same gang and kept unmixed with other cane until it is discharged from the vehicle conveying it to the railway. The success of the method depends upon a field super-visor who issues a ticket in respect of each heap of cut cane, which is put into a split cane on the heap. Upon that cane being loaded, the ticket is taken with the vehicle to the weighing station, where it is handed to the scale clerk, who records on his weigh ticket the necessary references. The tickets recording the weights are made out with sufficient carbon copies to provide one each for the trans-port man, the field office, and for permanent record. They are used for ascertaining the weights of cane handled by the various operators and the amount of pay due to each group, the total weight received and loaded at the railway and the yield of cane from each field. The identity of the individual groups of workers who have been concerned in the movement of the cane up to the time it is transferred to the railway car is not always preserved right through to the factory, though it can usually be traced with the help of the loading card which is attached to each car. This gives the name of the loading station, the variety of cane, the date and time of load-ing, and any supplementary particulars which may be required. It is important that the cane should be identified with the field in which it has been grown right through to the factory so that field records can include the juice characteristics and the sucrose con-tent, to enable yields of sugar per acre to be calculated. On arrival at the factory, the cane is weighed in the cars. This pro-vides a check on railway receiving stations. At the close of each week a statement is compiled in respect of each point, giving the

HARVESTING THE CANE 2 0 5

total tons of cane weighed at that point, and the corresponding figure derived from the factory scale records. Differences almost invariably occur as deficiencies at the factory, which by careful weighing at all points, good loading, and strict supervision, can be kept below 0.5% calculated on original weights. An individual figure of 1% or more calls for investigation and report. Cane losses may be apparent or real, the former due to inaccurate weight records, the latter caused by physical loss of cane by theft or by dropping from cars.

This system of identification is a development from earlier methods which pre-date mechanization. It could be simplified by the use of one gang of cutters for a field and one gang of loaders, each group sharing the proceeds of their collective work. No doubt the simpler method will evolve, but the strongly individualistic outlook of the sugar-cane field worker in many places is difficult to mould into one of group co-operation. The cost of supervision and accounting is high, and cutters do not always work regularly, which further increases the trouble of recording the work per-formed.

Working Groups Manual reaping by gangs of men combined with mechanical

loading and transport gives the impression of being more efficient, and certainly avoids the complications of the procedure just described. Working groups in multiples of eight are formed, and usually consist of 16 cutters, each group appointing a leader from amongst its members. One group reaps, and other groups deal with loading and transport. The proceeds of each operation in respect of a complete field are paid to the group and shared among the members by the leader. A spirit of competition is engendered by posting results for the groups who earn the most in a work-ing week. With this system continuous supervision is not re-quired. A field, say of 40 acres, estimated to yield 1,600 tons, is allotted to the gangs of cutters, loaders and transport men. The cane is weighed at the delivery point, and on completing the field, the amount due to each group is calculated and paid to the. leaders who give each man in their gang his proper share. After work has begun, an occasional visit by a field officer is all that is necessary and one man can take care of the work in a number of fields. The


identification of the cane with the field and the workers is quite simple.

H a r v e s t i n g S i d e l i g h t s

The omissions and mistakes made previously become apparent at harvest, not only on the weight and quality of the crop, but in their effect upon reaping and transport. The cumulative effect of such neglect may be serious, and cause among other things an increase in the cost of harvesting. Failure to control weeds in the early stages of the cane growth results in a tangled mass of inter-twined vines and cane to which manual cutters strongly object, and with which machines can only cope with great difficulty even after fire has been used. A further consequence is the trouble encountered in subsequent attempts to deal with weeds. Shortly before the commencement of the harvesting, attention should be devoted to all roads, intervals and traces over which vehicles have to move, and all repair and maintenance work completed in good time. Portable bridges are often required to enable vehicles to move over drains, irrigation channels, and other obstructions at points not permanently bridged. Equipment of this nature should be ready when wanted. Major repairs and alterations to field works may have to be undertaken during the crop period, when dry weather prevails. It is essential to plan these so as to avoid traffic obstructions and extensive diversions. The care with which all off season repair and maintenance work has been carried out on the full range of equipment and in harvesting operations will be well rewarded by smooth and regular movement of cane.

Cane Losses Losses of cane between the times of cutting and arrival at the

mill can occur through neglect in the field to load all cane reaped, by shedding from road and rail vehicles, and by theft. The extent of such losses is greater if the stalks are divided by cutters into two or more pieces—a traditional method which still persists to a small extent. Theft of cane from the field before reaping, and during all harvest operations may be a serious cause of loss. It has been estimated by observations in Jamaica that each worker accounted for 1 ton of cane per crop, which under the conditions prevailing at that time on the particular plantations concerned was equivalent


to approximately 1.5% of the total sugar produced. The softer canes then being grown have been progressively replaced by hard-rind varieties, which are less popular for chewing, though there is still considerable loss by this cause. Shedding from vehicles will be greatest at and near starting points, and at stopping places, that is at the field, the railway siding, and the factory yard. Regular picking up of such cane is worth while when the condition is serious.

CHAPTER 13

IRRIGATION

Primary Requirements Sugar-cane can be induced to yield heavily in suitable land where

rainfall is deficient or badly distributed, but where other climatic factors favour the crop, by the practice of irrigation. The term irrigation in this connection may be defined as the controlled application of water to crops on an extensive sale. The primary requirements for success are soils of satisfactory types and per-manent sources yielding large volumes of suitable water, which can be conveyed and applied to the land in regulated quantities at an economic cost. Though great variations are possible in the soil types in which irrigation can with advantage be practised, certain basic conditions are essential, and carefully conducted soil studies must precede the planning of an irrigation system. The primary requirement is the suitability of the land for sugar-cane as a continuing crop with or without rotation. The soil should possess good cultural characteristics, offer resistance to erosion, be well aerated and capable of storing moisture. Satis-factory quantities of essential plant nutrients should be present, and responses to the artificial application of deficient nutrients should be good, while it should be free from harmful chemical compounds. Good drainage is most important. As these are the characteristics of the best sugar-cane soils under conditions of adequate natural rainfall, it will be realized that with the exception of heavy clays there is no fundamental difference between those giving good crop yields under both conditions. Heavy clays dis-play adverse characters which result in poor response of the crop to irrigation. Aeration is deficient, and the penetration of water to the root zone is retarded so that continuous application to the surface for a sufficient time for it to get well down is necessary. In consequence evaporation losses are unusually high, and risks of damage to the soil increased.

208

IRRIGATION 209

The best soils for irrigation are deep alluvial deposits with good drainage. Such soils have high capacities for moisture storage, offer the most favourable conditions for good root development, and possess ample reserves of essential plant nutrients. Open sandy soils respond to irrigation, but percolation is rapid and moisture storage poor. As with shallow soils, frequent applications of water are necessary, and total water requirements high.

Quality of Water The quality of the water is highly important. Before establish-

ing irrigation works it is necessary to ascertain the quantity and composition of the dissolved salts in the proposed supply, and any seasonal variations which may occur, more particularly with waters obtained from underground supplies. Surface waters may occa-sionally alter in solid content and in the composition of the dis-solved solids. Of these the principal constituents which should be carefully and regularly checked are chlorides and sulphates. In general, waters containing not more than 600 parts of sodium chloride per million are safe ; 600 to 1,000 parts risky, and over 1,000 parts dangerous to the crop. These figures are, however, only approximate, as there are other considerations which affect the reactions of sugar-cane to irrigation water. Sodium carbonate is particularly dangerous, especially to loams and clays. Other factors are the nature, texture, and mineral composition of the soil, varietal tolerance, the frequency and amount of natural rainfall, the volumes of irrigation water applied, and soil drainage. The accumulation of salts, especially chlorides, in the soil will adversely affect the yield and composition of the cane, and lead to lower mill recoveries, thus reducing the value of the crop and the financial returns to the farmer.

Occasionally it will be found that certain toxic compounds de-rived from natural or artificial sources are present in excess of the tolerance of the crop. The micro-nutrient elements Boron, Zinc, Manganese, Copper and Molybdenum, which are so necessary in traces, become dangerous if present in still minute but greater concentrations than those actually required for the healthy development of the cane. There are still other elements which may cause damage to the crop. Arsenic, Barium, Chromium, Fluorine, Lead, Nickel, Selenium, Strontium, and Thallium


should be entirely absent in any soluble form, or present in ex-ceedingly minute quantities. The important significance of these facts is to emphasize the necessity of examining the sources of the water and of maintaining a constant and effective check upon its composition. If there is any suspicion that harmful industrial effluent or trade waste is discharged in such places that it may be introduced into the water used, even closer controls are essential.

Quantity Considerations The total quantity of water available, and its seasonal variation

will largely determine the area of land to be brought into an irriga-tion scheme. Factors to be taken into account are the minimum dry-season flow of water, the total effective rainfall and its distri-bution, and the water requirements of the cane. With surface supplies from rivers, streams and springs, gaugings over a mini-mum period of three years are advisable if there is any doubt about the total volume available per unit of time in relation to the area of land over which it can be efficiently distributed in adequate amount. Underground supplies are assessed by sinking bore-holes and pumping continuously under test conditions for pro-longed periods, or as is occasionally possible, by direct examina-tion when access to natural subterranean reservoirs is available.

In the absence of irrigation, sugar-cane requires a minimum effective rainfall of 60 in. to attain good yields. Effective rainfall implies well distributed precipitation in quantities which penetrate the soil to a sufficient depth to be available to the root system of the cane. Individual falls of rain which fulfil these conditions vary in quantity according to their frequency, and the permeability and nature of the soil. For practical purposes 0.5 to 0.75 in. in 24 hrs., except when the soil is saturated by previous rains, may be ac-cepted as the minimum effective precipitation. Total annual rainfall of 50 in. or more distributed over defined rainy seasons will provide in ordinary circumstances the full requirement of the crop, though if water is readily and cheaply available, it will even then be found advantageous to irrigate suitable soils in dry periods.

It is not possible to define closely the quantities of irrigation water required per unit area to supplement natural rainfall for all conditions ; each case must be considered in relation to a number of factors, and no generalized formula can be devised. Moreover,

IRRIGATION 211

it will be clear that unusual weather may bring about greater or lesser demand for irrigation water, and that the capacity of the supply and distribution system on the one hand, and of the drainage on the other, should be capable of providing within reasonable limits for such contingencies. When surface methods of water application are used as contrasted with sub-surface and overhead systems, the total water required for plant cane is from no to 120 in. over a growing period of 12 to 14 months. For ratoons, 90 to no in. during a period of 10 to 12 months will normally prove adequate. Surface irrigation to be effective con-sumes more water than the crop would need under natural rainfall to give the same result. Overhead watering is also accompanied by considerable loss and ineffective dissipation of water. For various reasons discussed later, surface irrigation schemes are relatively inefficient when judged on the proportion of the water taken from the supply which is actually made available to the plant. Individual applications need to be at the rate of 3 to 4 acre in. of water delivered to the field. Time intervals between succes-sive irrigations will range from 10 to 21 days during dry seasons, and will be governed by the rainfall and the condition of the crop during rainy periods.

As a general rule the total quantity of water required will vary inversely with the rainfall, but no rigid mathematical formula can be applied. The proportion of these quantities which will actually prove beneficial to the crop depends upon a range of conditions which will be appreciated from a consideration of the various causes of loss of water. These may conveniently be divided into line losses, that is those which occur between the water source and the field, and field losses. They include evaporation, absorption, and seepage or percolation.

Evaporation Losses Evaporation from open canals varies considerably, being in-

fluenced by temperature, and by movement of the water as well as by the air in contact with it. The higher the temperature of the air above the dew-point, the greater the rate of evaporation. This single loss, regarded as the least important of many causes of loss may account for as much as 10.3 gal. per 100 sq. ft. of surface per 34 hrs., calculated on a daily evaporation rate of 0.2 in. which is


by no means an unusual figure. Using the close approximation of 1 gal. loss per day for each 10 sq. ft. of water surface, a canal 10 miles long carrying a stream 5 ft. in width will lose 26,400 gal. by evaporation alone each day. The measurement of the rate of evaporation from a free water surface is referred to in Chapter 16. Though the data thus obtained refer to a particular meteorological element in respect of a free, exposed, but static surface of water, except for ripples induced by air movement, the figures can be used to give an approximation of the loss by evaporation of flowing water in irrigation canals, which is appreciably greater. Using the figure of 1 in. per week, which is commonly encountered, dry seasons amounting to 40 weeks in a year will be accompanied by a loss due to this single cause of 333 cu. ft. (20,636 gal.) of water for each 100 sq. ft. of surface.

Absorption and Percolation

Absorption and seepage or percolation cause much higher losses than this in earth canals. When such channels are used occasionally much greater amounts are lost than when they are in constant use. The former condition often applies to subsidiary canals of comparatively small capacity. The loss may amount to more than one-third of the total water received at the intake. In one extreme case involving long earthen canals, only one-half of the water entering the main canal reached the fields. The losses may be reduced by careful priming of new canals ; that is by allowing the water to enter and flow very slowly at first, and by clay puddling which brings about the deposit of a moist lining of clay which resists the passage of water through it. If a clay-lined canal is used intermittently, it must be carefully primed whenever it is brought into service.

Prevention of Losses

Losses by absorption and percolation in all permanent channels —main, distribution and subsidiary canals—are prevented by lining them with impervious material such as concrete for high rates of flow and cement plaster reinforced with mesh wire for small ones. Concrete slabs are used for large canals. Expansion joints of asphalt or other suitable material are necessary. In some

IRRIGATION 213

places old irrigation works with brick canals l ined (faced) with cement mortar, and brick arched aqueduc t s a re still in use. Apart from the serious water losses in ea r then canals, their high maintenance is costly, and must be taken into account when considering capital expenditure on the d i s t r ibu t ion system, as well as in determining the recurrent operating expenses of irrigation. To these causes of loss may be added t h a t b rought about by leakage, as contrasted with seepage or percolat ion, from defective parts of the system constructed with impervious materials.

Water is conveyed over depressions by me ta l fluming on wooden framework, embankments carrying ear then or concrete channels and by inverted siphons for which cement p ipe is often used. Obstacles such as roads and tramways are passed by siphons for which concrete formed on the site, or p ip ing of concrete or metal, is used. Drains can be by-passed in a similar manner , or by flum-ing or piping. Galvanized iron and a l u m i n i u m sheet are exten-sively used for permanent flumes, and for movab le channels in the field. The former may deteriorate quickly by erosion and corrosion of the surface exposed to the flowing water, so that it requires a protective coating. Tar is often used for this purpose.

The list of losses and wastage is by no m e a n s exhausted. Eva-poration from exposed soil in the early stages of establishing the crop is of the order of 0.5 in. for each irr igation, to which is added the further loss by the same cause during the pe r iod of drying out of the surface layer of the soil. The total loss in th i s manner may amount to more than 1 in. of water for each application until the plant has formed a protective canopy. F u r t h e r to this is the percolation of water through the small channels , apertures and crevices of the soil, which carry it beyond t h e roo t zone and thus render it unavailable to the plant. T h e object of an irrigation system is to get water to the fields in requ i red quantities at times when it is wanted. When water is available in amounts surplus to actual needs, from gravity sources, l ine losses a r e not a major consideration so long as waste causes no damage , b u t when it has to be pumped the cost of the water per un i t v o l u m e at the pump outflow point becomes a basic charge wh ich is increased in pro-portion to the quantities lost by evaporation, seepage, absorption, and leakage during its passage to the field in w h i c h it is to be used. The layout of main, subsidiary and minor d is t r ibut ion canals, the


design of the channels and the materials with which they are con-structed, must be carried out with these considerations in mind. In general, high cost water in limited supply should be conveyed by impervious mains and subsidiaries, with piped distribution to field supply points, or lined channels to take-off points at the fields. The use of cement-asbestos piping whenever comparative costs are in its favour is strongly to be recommended. In com-puting such comparative costs, maintenance charges and water losses must be taken into account. Accurate water measurement at points of discharge to the fields is essential, and much easier to arrange with pipes than with open channels.

Surface streams carry varying amounts of solids, or silt, and miscellaneous debris consisting mainly of vegetable matter such as fallen leaves, and floating water weeds. The latter is removed by screening at the intake. The silt, composed of clay and sand, of which the finer portions are in suspension and the coarse particles rolled along the bottom of the water course, can cause much trouble in an irrigation system. With gravity distribution direct from a stream level intake, deposition of much of the silt can be effected by the provision of basins or silt chambers of suit-able size in which the rate of flow, calculated in linear feet per unit of time, as contrasted with volume, is reduced to a minimum. The deposited solids can be removed by flushing out through low level controllable vents, or dug out by hand or mechanical means at convenient times. Where unlined earthen canals are used, water containing silt, of which a high proportion is clay, will soon pro-vide a less pervious inner coating and so seal off the canal surface exposed to the water with reduction of loss by absorption and seepage. This process should, however, be controlled by t h e means discussed to prevent reduction in capacity by the gradual filling of the channel.

Silt When the water supply has to be lifted to a distribution point

above the actual source, whether from streams or underground supplies, turbid water will cause heavy erosive wear on p u m p impellers, and other parts exposed to the water, particularly w h e n the silt is of a sandy nature. The apparent density of such waters is greater than that of pure water, and pump efficiencies will be

IRRIGATION 215

reduced by this factor as well as by unusual wear. A weight as high as 75 lb. per cu. ft. has been recorded for water heavily charged with silt.

Protection Against Floods Another danger with gravity systems from surface streams is

that of flooding during periods of unusually high flow caused by heavy rains. Head works must be protected in such a manner as to prevent the ingress of more water than the system is designed to carry and to close off the supply entirely if necessary. In any event, provision for regulating or stopping the water supply entering the system under normal conditions is needed, and it must be so designed as to cope with spates and floods. The effec-tive arrangement of suitable works for the safe by-passing of flood flow depends largely upon studies of the conditions over long periods. In the absence of accurately recorded data, accumulated local knowledge may be used, though except in areas remote from some modern form of reliable observation, there are probably few places where sufficient information has not been collected.

Erosion Soil erosion risks in an irrigation system should be avoided by

careful planning in the first instance, and by strict supervision and control of all operations. The presence of adequate organic matter in the soil is a helpful preventive factor. Points needing attention are correct field subdivisions, and short irrigation runs along very gentle slopes. During periods of irrigation, the flow of water must be effectively controlled and too rapid delivery avoided. Irrigators should be carefully selected and trained, and only supplied with volumes of water which they can use efficiently.

Surface Layout in Fields Initial preparation of land for planting must be carefully

arranged in relation to contours to give field supply or head ditch furrow slopes of 1 in 300 or less. From this the water is led into " twigs " or actual field furrows, which may have a slope of 1 in 75, but never more than 1 in 50. The " field supply " furrow or channel receives measured water from the main system. It may

p

2 l 6 AGRICULTURE OF THE SUGAR-CANE

be along one side of the field, serving several fields, or run across the field at an angle to the planted lines of cane. Constant gradients should be maintained in such field channels and for this reason it will be obvious that they cannot always be straight. These different slopes or gradients of ditches and furrows will vary with local factors. In general the more gradual the slope the less the danger of water getting out of control. Field furrows or " twigs " should be steeper than supply furrows or ditches to enable water to pass safely and quickly along the rows in order to give even distribu-tion.

Irrigation and Drainage Although irrigation systems originally developed for other crops

are now in many cases being successfully used for sugar-cane, the special needs of that crop require to be provided. It is true that the basic principles outlined apply to most economic crops cap-able of giving good responses to irrigation, but with the exception of orchard crops they are normally of a short life from planting to maturity, and are usually members of a rotational series with intervals between the plantings of successive and different crops which provide opportunities for correcting errors in original design and layout. Sugar-cane must be regarded as a permanent crop. A cycle of plant cane and one or more ratoons may be followed by a legume planted as a green manure crop to assist in maintaining and improving soil fertility for the main and continuing culture of sugar-cane. Initial mistakes in the planning of an irrigation system for sugar-cane are therefore not readily corrected, and since the basic consideration is the maintenance of soil conditions favourable to sugar production, even more care is essential in the preparatory stages. Apart from meeting the requirements already briefly outlined, the closest possible attention should be paid to drainage. Indeed irrigation and drainage are strictly comple-mentary and the former cannot successfully continue in the absence of the latter. Irreparable damage may be caused in many ways by ignoring this fundamental consideration.

The soil structure can be impaired ; the concentration of harm-ful salts increased in the upper horizons of the soil; the plant may be wholly or partially suffocated ; its growth checked rather than stimulated ; and ripening retarded or even entirely prevented.

IRRIGATION 217

Conditions must favour the retention by the soil of water for the use of the plant in the form of what is termed " soil moisture "— the extremely thin film of water tenaciously retained on the surface of each particle of soil. The saturation of the soil, brought about by the filling of the pores or spaces between individual soil particles, should only persist for a very short time after irrigation, though it is far better to avoid it entirely by control of applied water in such a manner that constant movement of water surplus to the " soil moisture " capacity takes place through the soil to the drains. A severe check to growth can occur by temporary water-logging or saturation of the soil.

Prevention of Salt Accumulation

The downward movement of water through the soil followed by percolation through the small and intricate channels to the drains is also important in preventing accumulations of dangerous salts in the upper layers. If this passage be retarded or prevented, the water evaporated from the surface of the land will leave a deposit of the salts it contained, to which will be added the evaporation residues of more water passing to the surface layers by capillary action. While this effect normally occurs with the evaporation of water on the surface, it is essential to keep it within safe limits. This can be done by drainage and by further irrigation, or rainfall, which will dissolve and remove the excess soluble salts.

Planning for Irrigation

It is clear that the basic needs for an irrigation project are suit-able land, and an adequate and suitable permanent water supply which can be used in controllable quantities where and when it is required. With these provisions in existence, the first step in planning is to map the area capable of being irrigated, showing contours and existing natural drainage. These factors being known, the water distribution scheme can be devised so as to supply the crop in a controlled manner, while necessarily avoiding any obstruction of the natural drainage system by main and distribu-tion canals and allowing free movement of percolation, waste and storm water to drains. The provision of necessary roads should be considered in the primary plan so that all flumes and siphons


needed to convey water over or under drains, roadways, and other works may be envisaged and planned for at the outset.

The general design of this scheme will depend upon whether a single water source providing ample volumes for an extensive area is available, or the water is to be obtained from several points, which may be wells or streams. If the whole or part of the total water is to be derived from wells, drilling and testing should pre-cede the construction of distribution works and field layouts. It is clearly desirable to make borings and to assess the quality and volume of the water available from each drilling during the period of the initial survey.

In many cases irrigation schemes are projected after land has been growing cane. Fields, roadways, intervals, drains and ancillary works exist already, and it is often difficult to superim-pose satisfactory water distribution without some modification of the original layout. In any event the irrigation water is led in at the higher points, applied to the land by graded channels, and the surplus, including run-off and percolation water discharged to the drainage system. It is often found possible to relift a proportion of the drainage water and to use it for further irrigation. When relift water is used there may be danger of an excess of harmful salts brought into solution during its previous passage through the soil.

Measuring Devices Measuring devices should be carefully located at all points from

which records are necessary. In their absence controls of water applications and costs are impossible. Apart from their value in this connection they provide a check upon loss and waste, and enable protective measures to be taken promptly. Various methods for water measurement are used including weirs with rectangular, trapezoidal and V apertures or notches, submerged vents, and modified Venturi flumes known as Parshall flumes. Weirs are suitable where there is a sufficient fall of water below the point at which measurement is to take place. Submerged vents need a smaller difference in level, while Parshall flumes can be con-veniently placed in most distribution and subsidiary channels, the dimensions being regulated by the volume rate of water flow. They give readings within 5% of true flow, a standard regarded as

IRRIGATION 219

being sufficiently close in irrigation work. The principles and practice of water measurement are described in various works which deal specifically with the subject of irrigation as an im-portant branch of civil engineering, and though applicable to the present discussion are more appropriately dealt with in detail in other publications, to which reference should be made.

220 AGRICULTURE OF T H E SUGAR-CANE

TABLE I FREE-FLOW DISCHARGE OF PARSHALL MEASURING FLUME

(Letters Ha and W refer to Fig. A.)

TABLE II DIMENSIONS AND CAPACITIES OF THE PARSHALL MEASURING FLUME, FOR VARIOUS THROAT WIDTHS (W)

IRRIGATION 221

FLOW OVER CONTRACTED, RECTANGULAR WEIR The following table is based on the King Formula for rectangular-notch

weir with end contractions :— Gal. (Amer.) per Minute = 449 X 3.34 (L — .2H) Ht.il

L = length of notch in ft. H = head above weir crest in ft.

When an empirical formula such as this is used for accurate measurement the weir must be constructed according to the dimensions used when securing the original experimental data. Whenever the King Formula is used the following requirements should be met :

1. The head above the weir crest must be measured accurately and at a distance of 2.5 times the weir head upstream from the weir, and pre-ferably at the side of the channel.

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2. The length of the weir notch must be at least three times the maximum value of the weir head to be measured.

3. The distance from the notch to the sides and bottom of the channel must be at least 2.5 times the maximum head to be measured.

4. The weir head should be at least 0.2 ft., and preferably less than 2.0 ft. 5. The nappe, or sheet of water falling from the weir, must be completely

surrounded by air. 6. The weir must be set with its crest level and its plane vertical. 7. The crest and sides of the notch must be smooth, sharp (900), and not

more than 1/16 in. wide. The upstream face of the weir plate should be smooth and set flush with the end of the supporting weir box.

Irrigation Methods There are several methods of applying irrigation water to the

land, but in the case of sugar-cane these are limited by practical considerations to :—

(a) furrow (b) overhead (c) sub-surface systems.

The latter two are at present used only to a very limited extent, overhead methods for this crop being still in the experimental stage, and sub-surface application confined to areas where special local conditions prevail.

Furrow irrigation may in some circumstances closely approach flood irrigation in which the whole area is covered with water and is confined by low embankments or bunds at the field edges. Though with heavy watering on almost level land the water over-flows the furrows and covers practically the whole area, the effect is to get most of the water into the ground by way of the furrows. Flood irrigation methods used for other crops such as rice, which involve the use of large volumes of inexpensive water, are not suited to the requirements of sugar-cane irrigation. Flood fallow-ing as practised in British Guiana is an operation distinct from the application of water to the growing crop.

Furrow Irrigation Surface irrigation along furrows is, then, generally practised.

It fits in well with standard methods of cane planting, and under proper working gets the maximum proportion of the water used to the root zone of the cane. Plantation and field layout must be such as to conform to the requirements of controlled movement of water to and through the fields in adequate quantity with uniform

IRRIGATION 223

wetting. The field furrows in which cane is planted must be graded by a slope which allows the water to move freely along them without erosive effect at a rate which can be regulated and controlled by the irrigators. The water reaches the field by a minor distributory, the field ditch, running along its highest side, which can be damned or checked at various points to divert water into the row furrows, or in some cases to larger field furrows which in turn feed into them. The planted furrows receive the water only in the earliest stages of cane growth, furrows being made between the rows in the ordinary course of cultivation as the cane develops. The irrigator works several furrows at a time, checking and releasing the water by the use of temporary earth dams made by abroad-bladed heavy hoe, in such a manner as to wet the soil as uniformly as possible. Sufficient water is needed to penetrate below the root zone and to effect this the time of contact of the water is regulated in relation to the rate of water movement down-wards into the soil. This is done by the skill born of long practice of the irrigators. In porous soils the water is absorbed quickly, while in clay loams and clays a longer time is taken to penetrate to a sufficient depth. Thus the grade of the furrows should be greater in porous soils than in other types to permit more rapid movement of water over the surface and to avoid waste. Uniform wetting is not easy to achieve and care is necessary to avoid giving too much water to the parts of the field nearest the field ditch. Thus the irrigators must be active in keeping the water moving, avoiding the formation of small ponds, and getting the water across the field in such a manner as to ensure adequate application through-out. As the first section of wetted furrows becomes saturated, the next section is opened, the water flowing over the saturated portion with little absorption there and so on until the edge of the field farthest from the ditch has been properly wetted. The depth of water penetration can be readily checked by an auger used in the manner described on p. 67.

Inter-Row Cultivation. As soon as possible after a field of newly planted, or young cane,

has been irrigated, the surface soil should be cultivated lightly. In the early stages this would be done as a normal operation including the " breaking of the bank," i.e., filling in the furrow in


which the cane is planted, and making new furrows near to the cane rows for subsequent irrigations. Just before the cane " covers down," that is, forms a complete canopy, row cultivation stops, and the field is left with shallow furrows between the rows. Later irrigations tend to fill these with soil so that in the final waterings conditions approaching those of flood irrigation may prevail in fields which are almost level.

Intervals Between Irrigation The intervals between irrigations vary from about 10 to 21

days, in accordance with general weather conditions and crop requirements. Visual examination of samples of soil withdrawn by the soil auger to a depth of 2 ft. or more in 6-in. stages and related to the appearance of the cane will prove of great help in deciding upon the need for irrigation. Growth rate measurements of selected canes in the field have been used to determine when further water application is necessary. Plotted against time, the growth rate curve shows a falling off when available soil moisture becomes depleted to the point of requiring replenishment if the cane is not to suffer from drought. At this stage irrigation restores the rate of growth, which continues until soil moisture again drops below the point requisite for normal plant growth. Reliable aids to water requirement diagnosis become of increased im-portance when water is costly and in limited supply. Various devices have been used for determining the soil moisture level at which irrigation becomes necessary.

The Crop Log Dr. H. F. Clements has evolved a graphic method of indicating the development of a crop of sugar-cane which is now widely used in Hawaii for production and ripening control under irrigated conditions. Fields are sampled at 35-day intervals after the age of about 3 months. The observations entered in the crop log kept for each field are related to atmospheric conditions, including temper-ature and sunlight, growth measurement, and moisture, nitrogen, potash and phosphoric acid status of leaf tissue. The index materials for total sugars, moisture, potash and phosphoric acid are the young leaf sheaths, the green weight of the sample being taken as a measure of general vigour. The tissue used for nitrogen

IRRIGATION 225

determination is the middle third of the young leaves. Applica-tions of fertilizer by this system are now controlled to the extent of more than one-third of the total production in Hawaii. The ripening control is effected by gradual reduction of the moisture in the leaf sheath from about 83 to 73 % brought about by regula-ting the application of irrigation water during the 7 months before harvest, during which period weekly samples of leaf sheaths are taken for determination of moisture. In this way the frequency and amount of irrigation are controlled in accordance with the indications of the cane itself. It has been found that the juice quality is improved, and that cane can be reaped at optimum maturity. The system has proved its value in the conduct of the controllable features of crop production in Hawaii, and has been used with success elsewhere, notably in some irrigated areas of Jamaica. It cannot, however, be safely applied generally in accordance with the established standards determined for Hawaii, and local investigation to ascertain such details must be under-taken before using it for commercial field control.

Conditions for Ripening Irrigation is discontinued some 6 weeks before a field is to be

reaped. The actual period varies with soil and climate, the object being to induce the cane to ripen or mature, and to yield the maximum return of recoverable sugar when milled. A prede-termined schedule of irrigation followed by a ripening period may be interfered with by the incidence of rain, or cloudy weather. The maturing process proceeds best under conditions of bright sunshine, comparatively low humidity, cool nights, and dry weather.

Overhead Irrigation Overhead irrigation simulating natural rainfall has been success-

fully developed for numerous crops, most of which are of short life and low growing habit. Truck crops as they are called respond to this system of watering. With sugar-cane the method appears promising under favourable conditions. It consists in spraying water above the growth level on to the crop and the land in which it is growing. The equipment used is of various types, but for sugar-cane consists of a pressure pumping system which supplies


the water through piping to rotating nozzles mounted on risers at a height sufficient to enable the water to be discharged above the cane. The pump and pipe system can be permanently installed, supply pipes to nozzles being buried in the ground below the cultivation level, that is, about 2 ft. 6 in. beneath the surface. Outlets are arranged at intervals so that risers with their rotating heads can be readily fixed and removed.

A portable system comprises a mobile power pump feeding into light alloy quick jointing portable pipes which supply the risers and rotating heads. While cheaper in first cost, this is more expensive to use, involving as it does skilled labour for moving and resetting the pipes and their ancillary equipment. Mobile pumps can be used with the permanent pipe system.

The rising pipes or risers connecting the rotating spray heads to the water mains must be stayed in position to keep them up-right, and of sufficient height to keep the emerging jet of water well above the cane. Should the jet be allowed to impinge directly on the cane, the force of water will cause damage. The length of riser used will vary from about 3 ft. for very young cane to 12 ft. for cane nearing full growth. Under ideal conditions the water is delivered evenly over the radius of a circle from the head as the centre to the limit of trajectory, which depends upon the type of nozzle and the pressure of the water. The head is mechanically rotated by the main or a supplementary water jet at a very slow speed. With some systems an acre or more is irrigated from a single head, the rate of water application being up to 1 in. or more per hr. Several heads are operated at one time, the distances between them being such that the circles of wetting overlap sufficiently to ensure that no part of the land is missed. This influences the distance apart of permanent mains and the intervals between the risers.

Some Disadvantages

From a consideration of the growth cycle of sugar-cane, certain disadvantages of the overhead method of irrigation will become apparent. The presence of adequate soil moisture is essential for the germination of the cane setts or " seed pieces," as it is for later growth and full development of the plant. It is evident that the overhead application of water will wet the whole area of the

IRRIGATION 227

field, and that an adequate quantity must be applied to the rows in which the cane is planted, so that a high proportion will fall on parts where it is not required, and where indeed it is undesirable to irrigate. The growth of weeds will thereby be encouraged, and apart from the cost of the extra water used, there will be additional trouble and expense for their control and eradication. At later stages similar conditions will prevail until the cane has formed a canopy, but in addition to watering the whole area as compared with the soil in the immediate vicinity of the growing plant by the furrow irrigation method, there will be interception of the falling drops by the leaves and stem, little of which will reach the ground, by far the greater proportion being evaporated. This effect will increase as the cane grows higher so that as much as 20% of the water leaving the sprinklers may be held by the leaves and stems. This quantity is reduced by movement caused by the wind, but on the other hand overhead watering is highly sensitive to air movement, and cannot be carried out efficiently in the manner described, except in still air or very light wind. The effect of wind is to disturb the pattern of water deposition which instead of being circular, as it is in calm air, becomes ovoid, with most of the water tailing on the leeward side of the rotating head. As the wind increases, some of the water becomes fine spray, much of which does not settle. Loss by evaporation is also increased. In these conditions it is not possible to get even distribution, and it is better not to attempt regular overhead irrigation in windy weather.

Whatever method is used, it is essential that the soil is wetted to the correct depth, so as to avoid the concentration of salts, by upward capillary movement of water followed by its evaporation, in the manner previously described. Thus while overhead systems which do simulate natural rainfall, appear to provide the best substitute for it, they possess certain drawbacks which must be considered before expensive installations are decided upon. There are, however, important advantages of the method, now to be discussed.

Important Advantages Irrigation of sugar-cane by the furrow method creates condi-

tions in the usually comparatively dry climate in which the plants


are growing, which while increasing the growth rate, stimulate transpiration. The plant at and for some days after irrigation has its root system amply supplied with water while its upper portions are in dry air, so that the rate of evapo-transpiration as it is called, is rapid, the plant acting, as it were, like a pump. With overhead watering a micro climate with more uniform humidity envelopes the whole plant, so that during and for an appreciable time after-wards transpiration is checked. For the remainder of the interval between successive irrigations similar conditions prevail with both systems.

When there is little or no movement of the air, overhead watering gives a far more uniform wetting to the whole land surface than does furrow irrigation. The comparative slowness of water application in the former case is a further important advan-tage. This ensures the thorough moistening of the soil to the proper depth before losses by seepage or percolation begin to be serious. Indeed by careful working it is possible to reduce these to a negligible minimum. Under good working conditions, closer control of water applied is possible and much less wastage occurs.

Added to these factors which favour an overhead system in suitable circumstances, is the avoidance of much of the damage to the physical condition of the surface soil which occurs with furrow irrigation, and which as has been shown requires inter-row cultivation as soon as possible after wetting in order to correct it. The effect is caused in three ways—by the trampling of the irrigators, the unavoidable puddling of loams and clays, leading subsequently to caking of the soil and upward capillary movement of water to an excessive extent, and the displacement of air. Over-head wetting involves far less movement of workpeople over the land, and with correct rates of sprinkling almost entirely avoids the second effect described.

The Irrigation of Ratoon Cane The Overhead Method for Ratoons

So far conditions which apply only to plant cane have been discussed. The succeeding ratoon crops differ in their require-ments at the outset of their growth. When the plant cane has been reaped, the land is left with a covering of dried cane trash consisting of leaves and such of the tops as are not used for cattle

IRRIGATION 229

food or for planting. The rows of cane stumps from which the ratoon crop grows lie beneath this covering and cannot be watered by the furrow method unless the trash is moved to one side and new furrows made to carry and apply the water. The mat of trash can be cut by an implement of which the essential part is a notched disc, and a furrow made by a furrower or middle buster attached behind the disc. Surface watering can then be conducted. With overhead application, no cutting or movement of the trash is necessary, but the volume of water used must be sufficient thor-oughly to wet the ground to the necessary depth, and in the course of this the trash will intercept and hold a high proportion of it. On the other hand the trash acts as a mulch which checks evaporation from the soil surface and suppresses the growth of weeds. The thorough wetting of the trash with each sprinkling causes it to settle into a compact mat over the land surface, and brings about its more rapid decomposition. The solution and movement into the soil of artificial fertilizers, necessary to vigor-ous growth of the cane, is efficiently effected by overhead watering. Furrow irrigation usually involves the placing of the fertilizers in or on the soil, though it is possible to apply them in solution in the irrigation water. With overhead sprinkling they can be applied over the rows on the trash, or not necessarily on the land surface itself, as the effect of watering will be to get the material on and into the soil by solution and mechanical transference followed by solution. Though in some cases it is preferable to get fertilizers under the soil surface at the time they are applied, it is necessary to compute the comparative costs in relation to the ultimate effect on the crop and the financial returns derived from it, when it will often be found that the additional labour and expense of more intricate, though more effective methods, are unwarranted.

Factors Affecting Overhead Systems Overhead irrigation involves the delivery of water from an

irrigation ditch or other source of supply through the distribution pipes to rotating heads under pressure in sufficient volume to operate the system at its rated capacity. There are various types of sprinkler heads differing in construction and capacity and range of delivery. The volume-pressure relation to serve a group of


heads must be correct and constant to make sure that the full circle of wetting is attained and the delivery rate of water on the land conforms to the operating specification. This is especially important when a permanent field piping system is installed. The various heads have individual pressure-volume characteristics typical examples of which are given in the table, which also shows the rate of wetting in terms of inches of water per hour. Pump capacity and power, pipe size, and sprinkler-head rating must be carefully integrated if the work is to be performed efficiently and at the lowest possible cost. The initial cost of the water at the suction side of the pump is increased by the expense of raising it to the pressure required for efficient operation of the rotating heads. Thus a pressure of 80 p.s.i. at the head, using water that has already been lifted from a well with a 150-ft. static level, will rather more than double the actual cost of the water reaching the soil by way of the sprinkler, while the cost of applied gravity water—that is, water not previously pumped—will be increased in greater proportion, as compared with surface irrigation methods. The additional capital cost of pressure sprinkler insallations with their standing and maintenance charges must also be taken into account when assessing the cost of irrigation by overhead methods. As has been shown, there are compensating advantages for these higher costs. These favour the use of overhead methods when the initial cost of the water is high, as with high lift pumping, and when the configuration of the land renders furrow watering difficult and highly wasteful. For nursery work in the growth and testing of new cane varieties, and field experimental work under irrigated conditions, overhead watering is preferable as it is capable of closer control and more uniform distribution of the water used.

Overhead Irrigation in Puerto Rico The nature and extent of the experimental work required for the

investigation of an overhead irrigation system for sugar-cane is indicated by an article recently published in the International Sugar Journal*:. A section of sugar-cane land of 80 acres in extent was selected for the trial, and of this 77.5 acres were actually covered—6 in. transite pipes were laid 44 in. below the surface forming a permanent water distribution system well below the

* I.S.J. July, 1951.

-.ring and

rider able Lsed.

: the Le is onal tent tally face the

IRRIGATION 231


cultivation level and safe from damage by tractors. The total length of pipe was 9,000 ft. Galvanized 4-in. " T " connections were provided on approximately 375-ft. centres, and above these risers standing 12 ft. above ground level were mounted, being supported by 4 X 4 ft. concrete blocks at the base, which was the level of the underground pipe, rising to 2 ft. above the ground where they tapered to 2 X 2 ft. The risers had flanges at the top, to which nozzles could be bolted as required. The total number of risers was 31, of which 2 were operated at a time. A diesel pumping system drawing its supply from a 10,000 gal. sump which received water from an irrigation main ditch, was located at the centre, providing an average pressure at the nozzles of 120 p.s.i. and delivering 750 g.p.m. (American), per nozzle. Two nozzles were operated at a time for 90 minutes at each irrigation, supplying 0.98 to 1 acre/in. during that period. In the absence of wind each nozzle covered z\ acres, making one revolution in 10 to 15 minutes. Under these conditions the stream was discharged for a distance of 240 ft. Rotation of the nozzles was effected by an incorporated water motor and it was found necessary to carry out irrigation at night because of the prevalence of wind during day-light hours. In still air the nozzle design permitted the discharge of a stream which fell in the form of a curtain throughout its length, giving a satisfactorily even distribution.

The indicated efficiency of the overhead irrigation method was 77% as compared with 50% for surface application made on other parts of the estate. A total of 41.028 acre/ in. was pumped in 13 months, during which there were 32.18 in. of rain. An increase of 9 tons of cane per acre and 1.6 short tons of sugar per acre were recorded in comparison with surrounding fields which were furrow irrigated. The elimination of all irrigation ditches brought about a saving of 5 acres over the total area, a factor which ac-counted for a part of the increase in yield. It was observed that the surface soil was in much better condition than when surface irrigation was practised.

Application of Fertilizers in Irrigation Water Some success has been achieved in the application of readily

soluble artificial fertilizers to sugar-cane through the medium of the irrigation water, and provided that field conditions and the

IRRIGATION 233

irrigation method used permit of uniform distribution of the water, the system has much to commend it. Disadvantages are that with furrow irrigation methods it is not possible by this means alone to regulate the dosage so as to provide for the special needs of known spots of lower or higher than average fertility. Distribution by surface watering in this way is, however, more likely to give a uniform distribution than hand methods, though the whole of the surface receives fertilizer instead of places immediately above or near to the root zone, particularly in the case of young cane.

Overhead irrigation appears to offer a much more promising method as a vehicle for the supply of fertilizers to the land and the crop, more particularly with nitrogenous types. The attention now being given to the distribution of nitrogenous fertilizers by aeroplanes in order to get absorption of nitrogen compounds through the leaves of the cane, could well be replaced by irrigating through overhead systems using water containing the rated quantity of nitrogenous compound. Distribution of such material by aeroplanes is very expensive and subject to the risk of irregular application. The recent introduction of liquid ammonia as an artificial nitrogenous fertilizer has already brought about changes not only in the material of nitrogenous manures, but in their method of application, and the possibilities of distributing diluted ammonia solution by overhead irrigation offers great promise.

Subsoil Irrigation Subsoil irrigation is practised for some crops under special

conditions where a pervious soil overlies an impervious layer just below the root zone. Channels dug at intervals through the fields are filled with water which penetrates the soil below the surface and supplies the needs of the growing crops. The method is not suitable for sugar-cane, though subsoil watering can be used in certain circumstances, as for example, in the cane growing districts of the Everglades in Florida where there are vast areas of almost level deep organic soil of high fertility. This land has been most carefully drained by an extensive main system of canals and feeder drains which are controlled and regulated by sluices and high volume low-lift pumps. The cane fields each 40 acres in extent are mole-drained, the channels being made 3 ft. below the surface at 15-ft. intervals. These mole-channels discharge drainage


water into the head drains at the side of the field and then to the main system. When the soil becomes dry and the cane insuffi-ciently supplied with moisture, the water level in the head drains is raised so that water flows from them into the moles and thus reaches the root zone of the cane. The water thus applied is not measured. The cost of the subsoil method is negligible as the drainage system is essential to successful cane production, and no other special arrangements are required to regulate the water.

Dry Season Irrigation Many places where sugar-cane is grown would benefit from

irrigation given adequate supplies of water at the time it is most needed at an economic cost. Annual weather cycles usually fall into well-defined wet and dry seasons, and the rate of growth of the cane conforms to a similar pattern. The sequence of planta-tion operations depends so much on water for the crop in sufficient quantity at the right time that some irrigation is of profitable assistance to supplement rainfall even when the latter may appear to approach the total optimum needs of the crop when judged by annual figures. With irrigation under low rainfall conditions planting and reaping can be carried on almost at will during the greater part of the year, while with higher rainfall, crops can be planted and induced to grow during the dry season, and ratoons stimulated to yield more heavily. Under favourable conditions where high uniformity of water application is attainable, artificial fertilizers can be carried in solution in the irrigation water and the separate operations of fertilizer distribution avoided. Similarly, factory residues, such as filter mud, can be discharged into the irrigation water and thus deposited in the fields.

Design of Irrigation Schemes Having discussed the merits of irrigation, compared the relative

advantages of the surface and overhead methods of watering, and described important points of detail, the subject of general planning remains to be considered with respect to the special needs of irrigation. It will be clear that the main aspects of this must conform to the principles laid down in the- Chapters dealing with drainage and plantation and field planning. Particular attention must be paid to the initial survey work especially to

IRRIGATION 235

contouring, which should be meticulously carried out, vertical intervals being not more than 2 ft., and preferably 1 ft. In almost level land the latter is essential.

The next step will depend upon the nature of the water supply. If a high volume and adequate quantity of water is available, whether from a gravity or an underground source, the whole area will be planned as an individual unit, or as a part of several independently owned plantations to which water is supplied by a central authority. The latter will be discussed later. Should the water be pumped, the water supply characters of the available underground source having already been tested, well sites are selected and wells constructed as already described, the extent of the area commanded by each then being determined.

With the sources and volumes of water available thus known, the main and distributory canal system can be set out on plan, together with field boundaries, main and internal roadways and intervals, tramways, the drainage system, and other services among which is included the electrical transmission system if electric pumping from well is to be practised. The points at which measurement of water is to be made, and the type of device used for this purpose at each should as far as possible be decided so that the construction of the distribution system will include the necessary installation. The position and nature of regulating apparatus, such as sluices, gates, valves, distribution boxes and canal drops in high gradient sections, will also be planned in advance. Too much care cannot be devoted to the preparation of plans, which should depict pro-posed future development as well as that contemplated for im-mediate execution.

It will be seen that so far the procedure described applies to areas which are to be developed, rather than those where cane is already grown but in which the installation of an irrigation system is proposed. There is a third case—that of an existing sugar-cane plantation with adjoining land capable of development.

Special Considerations Affecting Land Already in Cane

The second type of project, the application of irrigation to land in which cane has previously been grown under natural rainfall conditions, requires the preliminary detailed survey work which


has been described. In many of the older plantations any existing survey is often confined to a picturesque depiction of the boun-daries with major subdivisions and decorative but inaccurate indications of a few main features. With land already in cane surface survey will be difficult and protracted, though an aerial photographic survey can be rapidly made. Contouring can only be properly carried out when the crop is off the land and may take several years to complete. Much, however, can be accomplished by observations made in the intervals, roadways and in fields just reaped, newly planted, or under fallow, the final details being filled in when opportunity offers. It will often be found that the reform-ing of fields, relocation of intervals, and modification of the drainage system are necessary—indeed it would be surprising if they were not! The cost of altering irrigation water distribution is heavy, particularly if impervious canal lining is used or the land levels vary considerably. Every endeavour should therefore be made to locate the water distribution system on a permanent basis.

Existing natural drainage, which determines to a great extent the main drainage of the land, must not be impeded by canals or other works, and therefore should be shown on the original plans on which the whole layout is to be plotted. Other matters have been already discussed in detail, but as they are of importance in planning as well as operation, a brief recapitulation is helpful. Field design should take into account the desirability of short irrigation runs along very gentle slopes with the object of ease of control and uniformity of application of water. Fields should therefore be preferably rectangular with the field supply ditch running along a longer side. "Where a trapezoidal layout is neces-sary the ditch should be on one of the longer sides. The head drain will then usually be best sited on the opposite side of the field, the location and extent of the drains in the field depending upon the nature of the soil and subsoil, so that the general move-ment of water in the soil is in the direction from the irrigation ditch to the field drain. It is essential that the irrigation and drainage be separate systems, the latter being designed with rela-tion to the former. The possibility of relifting drainage water is a matter for later investigation when the system is in operation as a whole.

IRRIGATION 237

Field Design and Grouping Field grouping in such a manner that a feeder canal can supply

a number of field ditches is important in regard to water economy, and ease of supervision. The total area of a field group depends on the water-carrying capacity of the feeder canal, the rate of applica-tion and the frequency of irrigation. An ideal arrangement is a group which can be so watered that when the lowest in the group has been irrigated, the highest is ready to receive its next watering, the cycle of watering being in the direction of the highest to the lowest. It will be obvious that such a group will at the same time usually be a drainage unit.

Similar considerations apply to the cropping cycle—the sequence of plants and ratoons. Each group or block of fields should be in the same stage of a cycle at the same time, again with the object of economy and efficiency in the use of water, as well as for other important considerations discussed in detail in Chapter 8, notably the organization, supervision and control of all other field operations.

Legal Considerations The use and disposal of water involves relations with public

authorities and other land owners. While details of legislation and methods of administration vary in different countries, the main principles of water conservancy underlie them all. These are the protection of public water supplies which affect the interests of communities, legal control of the use of such water, and the regulation of drainage. Other matters relate to riparian rights, pollution and fouling, irrigation and drainage services and rates, and rights of way. An essential preliminary to the consideration of a private irrigation scheme is a determination of the planter's legal position with respect to these and all related matters. There is an increasing and justifiable tendency to extend public interest and control even in respect of springs and wells on privately owned property. The basis of this is the fact that the water which supplies them is derived from rain and snow deposited elsewhere, while the outflow affects the amenities of other land through which it passes. With wells, such as those which have been described, there is in some cases a risk of over-exploitation of the under-ground supply, leading to reduced pumping discharge and in


extreme cases to increases in salinity, or complete failure of one or more of them. Thus in an extensive fertile plan with good quality water beneath it, yielding heavy crops of cane, it has been found that some of the tube wells interfere with each other when more than one is pumped at the same time. The nature of the interference is reduction of capacity, increase of static head and rise in salinity, all of which point to the fact that maximum pump-ing from such wells in any area may easily attain limits which it is dangerous to exceed. This reveals the necessity for some effective control of well boring in such localities where the land is farmed by more than one owner, and the keeping of proper records of all wells in use in the individual interests of the planter as well as to safeguard those of a water using community.

Daylight Working and Night Storage The important question of what may be termed " night water "

remains to be considered. It is one which affects initial planning and subsequent operation of an irrigation system. Experience has shown that the use of surface methods of irrigation during the hours of darkness is wasteful, inefficient, costly and dangerous. Overhead methods except in very favourable circumstances have the same drawbacks, perhaps to a lesser extent. Waste occurs because of the ease with which water can get out of control, a situation which becomes more probable when irrigators cannot see distinctly. Inefficiency arises from irregular distribution through the field. Increased costs are due to these causes, to the necessity for stricter supervision and the need for artificial light. When night working was practised hurricane lamps burning kerosene were used. The light emitted was insufficient to enable good work to be done, and accidents from overturned lanterns which caused firing of the cane were of frequent occurrence. There has been, therefore, a general tendency to confine the actual application of water to the fields to daylight working only. T h e problem is simple when the water is derived from a gravity source, provided it is shut off at night in the subsidiary feeders and at the intake so that the whole canal system is kept full and working can be resumed in the morning without waiting for water. Large pumped volumes are more troublesome. Apart from tube wells serving small compact field groups, the solution is to pump con-

IRRIGATION 239

tinuously and to store the water during the night in dams or reservoirs from which it can be released to the feeder distribution system and the field ditches with the minimum of loss and delay (Fig. 24). This has been successfully arranged with large schemes. It results in pumping plant being used to its maximum efficient output, and in a limitation of pump size and main canal capacity in relation to the total area commanded, since for practical pur-poses, the pumps and main canal system are operating as if the water obtained were being continuous applied to the fields.

Where such storage dams or reservoirs have not been estab-lished, pump and canal capacities must be at least doubled to serve the same area with irrigation during the day only. Similarly, for a given installation, daylight working halves the area capable of receiving water from it unless storage for night water is provided. Where the topography lends itself to the construction and use of night storage, endeavours should be made to include provision for it when planning a scheme.

Underground Water The use of underground water supplies for irrigation has

developed in a notable manner during recent years. Methods originally devised for orchard and truck crops are now applied with success to sugar-cane. In broad outline they involve well sinking and the pumping of the water to the surface where it is discharged into a feeder canal for distribution throughout a system, the extent of which is governed by the volume of the water and the crop for which it is used. Civil engineering problems are encountered in the construction of such wells, which includes sinking, lining, developing, proving and the installation of pump-ing units. Before embarking upon well projects it is essential to have prior knowledge of the water bearing strata, the permanence of the water supply and its quality, the depth at which adequate supplies are likely to be obtained, and other relevant matters. Geological surveys are of the greatest assistance in indicating the existence of supplies and the prospects of their successful exploita-tion. Trial borings made under the advice and supervision of an experienced civil engineer who has specialized in hydraulics should always be the preliminary step in the exploration of under-ground supplies. In selecting sites for wells in a known and


proved area, preference should be given to places which satis-factorily command the land to be irrigated without being higher than will provide for satisfactory gravity distribution of the water.

Open and Closed Wells The types of well may conveniently be classified as open and

closed. The typical example of an open type well is a shallow excavated shaft of circular section lined with masonry. Such wells, while easily constructed to small depths, cannot be sunk more than a few feet below the water level, though they can be supplemented by mechanical boring at lower levels and the use of perforated linings as for tube wells.

The " closed " type—a term used for convenience, consists of a shaft sunk mechanically and lined with a metal tube, the lower sections of which are perforated with apertures of a size related to the nature of the strata encountered in the lower levels of the well. Such wells are usually sunk to depths considerably greater than that at which water first begins to flow into the shaft, the object being to tap the supplies available in permanent water bearing strata (Fig. 28). They are best located where porous rock, particu-larly limestone occurs at lower levels in large basins through which water flows underground from extensive hilly catchments. In such cases the water is usually of high quality, and more constant in composition, while the supply is normally reliable in regard to volume. Wells sunk in clay with occasional horizons of sand and gravel are liable to fluctuate considerably in quality and volume of the water, the variations being related to periods of heavy rain and dry weather, both in the immediate area in which they are situated, and in the more distant catchment from which the main supply of water is derived.

Developing and Proving a Well The development of a tube well is the process by which the

finer particles of material surrounding the screened portions of the casing within the water bearing strata are removed so that the flow of water into the well is assisted. This is done by alternate surging and baling. The surging effect may be produced by a solid plunger worked up and down in the water, by compressed

IRRIGATION 241

air suddenly released in the water in large volumes, or by back washing the well. Back washing may be done by pumping to maximum capacity, and then stopping the pump. The water in the pump column falls back into the well, creating a surge. There are other methods which depend on the same principle. This has the effect of causing the fine material to pass through the screen, when it is removed by baling. The surging and baling are con-tinued until no more fine particles pass through and may occupy periods ranging from a few hours to several weeks. The well is proved or tested by continuous pumping, during which measure-ments are made of the volume of discharge, the depression of water level and the pumping depth at various rates of pumping. The period of such testing may extend to several days, the final stage being steady pumping at the optimum discharge rate indi-cated by the earlier tests.

Characteristics of a Well An important feature of the characteristics of such a well is the

draw down, or the depression of the water level in the well caused by pumping. The two factors are related in that the former should be steady for given rates of pumping until the flow of water into the well is at a maximum consistent with safe pumping. It may be found that the draw down is excessive in which event a lower sustained pumping rate will be decided upon. It is desirable that the draw down should be kept low, i.e., at a minimum as otherwise the hydraulic gradient in the water bearing strata becomes too steep, with the attendant risk of movement of loose particles towards the screen of the well tube and a reduction of yield which may in extreme cases damage the well. Knowledge of the char-acteristics of a well is essential to determine the pump capacity and power required to lift the water and the area which can be irrigated by it.

The results of the testing determine the specification of the pump and the power unit to drive it, which cannot be ordered until certain essential data are known. These are the static water level, which is the head of water in the well before pumping is started ; the draw down, or the depression of the water in the well caused by pumping ; and the volume of discharge per unit of time when pumping from that level.

FIG. 25.—Pomona

[Courtesy of Fairbanks, Morse & Co. Deep-well pump.


Pumps The pumps most suitable for irrigation wells are the horizontal

shaft centrifugal and vertical shaft turbine types. The former is limited to suction lifts not exceeding 25 ft. at sea level. A varied selection is available, and efficiency is high. In order to take advantage of the better performance of centrifugal pumps, they may in suitable circumstances be placed in an underground chamber so as to be at an economic working height above the level in the well. The water can be forced above the pump level to a considerable height if necessary. The specification of the pump for any particular set of conditions depends upon the suction lift, volume to be pumped per second, height of delivery outlet above the pump level, and the nature of the driving power.

The turbine pump employs an immersed rotating impeller to lift the water (Fig. 25). The impeller, of which the blades are so designed as to force the water upwards by their movement through it, is fixed to a vertical shaft with bearings at intervals, the drive being effected at the top. The whole is mounted in a tubed casing having a strainer chamber surrounding the impeller, suspended in the well. The casing provides support for the pump and a rising main for the water which is discharged at the top. The efficiency of turbine pumps is lower than that of centrifugal pumps. The latter can be readily examined and if necessary easily dismantled and repaired, while the turbine pump has to be completely with-drawn from the well for such purposes. Impellers need regular examination to ascertain the extent of wear and to determine when repairs or replacements are necessary. This is rather troublesome and there is therefore a tendency to run such pumps for long periods without overhaul. Efficiency drops and pumping costs are thereby increased. Turbine pumps, however, have the advantage of ability to lift water from considerable depths, the present accepted limit being 500 ft. (Fig. 26).

The most convenient and easily controlled power for such pumps is electricity. Automatic control is then possible, and maintenance is simple. With turbine pumps, the motor is usually mounted vertically on the shaft thus providing direct drive. Internal combustion engines are widely used for both types of pump, power being transmitted by belt and pulley. Suction gas engines have been used where suitable fuel was plentiful and

IRRIGATION 245

cheap, but the modern diesel and electric power units have replaced them. Steam plants for high volume pumping still exist, but are now usually standby units for use only in emergency.

Economic Pumping Depth The economical depth from which water can be profitably

lifted for sugar-cane irrigation depends upon a number of factors the principal ones being the increases in yield and value of the crop, the cost of power, and the actual cost of the water per unit of production. The last item should be reduced to terms both of cane and sugar. It includes all charges related to the total irrigation water used to grow the crop. It will be realized that where other costs of production are comparatively low, i.e., general field charges including land operations, planting, manuring, weeding and reaping, more can be spent on water. The converse is also true. Thus in some areas the economic pumping limit is 80 ft. and then many of the other costs of cane growing are relatively high. On the other hand, extensive irrigation of sugar-cane is carried out profitably with lifts up to 500 ft. The necessity for careful cost analysis and control is apparent.

Power The power required to lift water may be readily ascertained from

known data. The basic unit of 1 h.p. is equivalent to 33,000 ft. lb. of work per minute of time, or in other words, a weight of 33,000 lb. lifted through a vertical height of 1 ft. in each minute; 1 cu. ft. of water at 62º F. weighs 62.4 lb. very nearly, so that 1 h.p. will lift 528.8 (say 530) cu. ft. of water to a height of 1 ft. in 1 minute. Assuming 100% pump efficiency h.p. will lift 60 X 530 = 31,800 cu. ft. in 1 hr. The power required to lift a given number of cubic feet of water per minute (C.F.M.) through a vertical distance (H) is therefore :—

(i) at 100% pump efficiency.

It is necessary to know the pump h.p. hours required to lift a total volume of V cubic feet, as from this can be calculated the cost of the water delivered at the pump :—

again at 100% pump efficiency.


The efficiency rating of pumps varies considerably, the maximum being about 75%. With turbine pumps it may drop to below 50%. Assuming 70% pump efficiency, the formulae quoted become:—

(i) Actual power required

(ii) h.p. hrs. for total volume V

It should be noted that the figure 530 is an approximation for 528.8 and 31,800 for the more correct figure of 31,728. In practice the approximate figures are satisfactory.

Horsepower required to pump 1 cu. ft. of water per sec. (1 cusec) through a height of 1 to 100 ft. at 70% pump efficiency :—

Height in ft. h.p. Height in ft. h.p. 1 .162 50 8.1 5 .81 60 9.72

10 1.62 70 11.34 20 3.24 80 12.96 30 4.86 90 14.58 40 6.48 100 16.2

Electric power is measured in kilowatt hours, 1 KWH being 1,000 watts applied for 1 hr. equivalent to 1.34 h.p. hrs. One KWH is commonly called one electrical unit of power, or one "unit," being the basis on which charges for electric power are calculated. Assuming that electric motors have an efficiency of 88%, 1 KWH provides 1.18 h.p. From a knowledge of the cost per unit of electricity at the pump site it is a simple matter to calculate the cost of pumping a given volume of water. An example will illustrate the method :—

Volume to be pumped .. 2½ cusecs Lift 35 ft. Pump efficiency .. .. 75 % Electric motor efficiency .. 88% CFM

h.p. required

IRRIGATION 247

KWH required at 88% motor efficiency

Cost per hour for 2½ cusecs = 11.2 x 0.33d. at 0.33d. per KWH = 3-7d. 2½ cu. sec. == 9,000 cu. ft. per hour. Cost of pumping per 1,000 cu. ft. = o.4d. very nearly. Cost of pumping per 1,000 imp.

gal. .. .. .. .. = o.o66d. Cost of pumping per cu. ft. for

1,000 hrs. . . . . . . = £6 3s. 4d. NOTE.—1 cu. sec. = 3734 imp. gal. per min.

= 448.8 U.S. gal. per min. 375 imp. gal. and 450 U.S. gal. are the close approximations generally used.

Comparison Between Electric Motor at 88% Efficiency and Diesel Engine

Volume to be pumped .. .. 5 cusec. Pumping lift . . . . . . . . 100 ft. h.p. required .. .. .. .. 80 (very nearly) Fuel consumption for diesel (0.42 lb.

per h.p. hr.) . . . . . . 33.6 lb. per hr. Cost of electric power .. .. o.35d. KWH

KWH required = 68

Cost of electric power per hr. .. 68 x .35d. = 23.8d.

This is equivalent to diesel fuel at o.7o8d. per lb., or £6 12s. per ton.

Height of Discharge It is important that pumps should discharge at the actual height

required to provide a surface level supply of water to the receiving basin or main canal and not higher. In many cases the pump orifice is observed to be from 1 to 3 ft. higher than this, the result being that additional pumping costs are incurred with no advantage, as the energy of the water in its fall to the basin or canal level is wasted. The cost of pumping is very closely proportional to the lift so that in the example just quoted, if the required lift of 35 ft.

R


is increased by 2 ft., the cost of the water is nearly 6% greater than it need be. An argument against discharging from the pump orifice at the same level as the water in the receiving basin or canal is that the surging inflow when the pump stops may cause damage. This may be easily overcome by a simple check valve or gate which automatically closes immediately the flow from the pump stops.

Selection of Pumps The selection of a pump and its power unit for any given set of

operating conditions requires the careful consideration of an expert in such matters. It will be found that the type, make and capacity of the pump decided upon will provide economic working under certain limiting conditions which will be described in information supplied by the manufacturers. As well as operating and maintenance instructions, an important part of the data will be the " pump characteristics." These differ for various sizes and makes, and show diagrammatically the performance of the pump and the power required over a range of working conditions. A typical pump characteristic diagram is shown in Fig. 27.

Maintenance and Operation It is essential that all working parts of the pump be properly

maintained in first-class order if the characteristic diagram is to be of continuing value. Worn impellers and bearings, and poor shaft alignment are common causes of efficiency drops. An independent check on the general condition of the installation is provided by regular study of recorded operating data, including power consumed and volume of water lifted, both of which must be determined by actual measurement, times of operation, and rate of pumping per hour.

A pump in normal working condition should conform to its " characteristics," but it is unwise to assume that for a given head and power consumption, the water delivered is the amount indicated by a scrutiny of the diagram, as the efficiency may have changed. The importance of measuring irrigation water at its source, and at other points has been discussed. This applies to water delivered by pumps, which should be metered in some accurate and convenient manner as soon as possible after it leaves the pump, and the agitation caused by inflow from the discharge


has subsided. Such records should be made at fixed times, the power consumption and static head readings being also taken. From this data a constant check can be kept on pumping efficiency as well as on other important requirements of control. In addition to these points, the constant and regular observations made will give indications of any abnormal behaviour of the well itself, which if encountered must be promptly investigated—again a job for the expert.

Natural Reservoirs In some countries underground water supplies occur in caverns

and natural subterranean reservoirs where conditions enable pumping machinery to be erected in underground chambers near to the water surface. In such circumstances it is often convenient to use horizontal shaft centrifugal pumps with rising mains to convey the water to the surface through open shafts. The complications of tube wells are avoided, efficiency is higher, and the water can be forced to any required height by single or multiple stage pumps.

A High-Lift High-Volume System An interesting high-lift surface pumping and irrigation system

covering 12,000 acres of cane land is owned and operated by Natal Estates Ltd., in Natal, South Africa. Water is taken from the Umgeni River and lifted by six 600 h.p. five-stage electrically-driven rotary pumps to a height of 498 ft. through a pipe 3 ft. in diameter and 1,000 ft. long, being delivered to a concrete main canal 14 miles long. The pumps deliver a total of 42 cusecs or 943,500 gal./hr. There are, in addition, subsidiary pumps taking water from various streams, and providing an additional 31 cusecs. equivalent to 696,400 gal./hr. Electric power is generated by a 9,000-kW. plant at the sugar factory. The distribution system includes secondary concrete canals, cement-plaster subsidiary canals with wire-netting reinforcement, asbestos-cement pipes and inverted syphons. There are 39 dams or reservoirs with capacities ranging from 3 million to 250,000 gal. These are used to impound water pumped during the night, as actual irrigation of the land is only carried out during daylight. During irrigation periods the pumps run continuously.


To those accustomed to irrigation works on flat lands, the application of large volumes of water to cane by surface methods in rolling country with steep hillsides is rather startling. Great care is taken to keep the water under control at all times, and to prevent erosion. Measurement is made at every take-off point on the main canal, using rectangular weirs, and at other places. Filter mud is applied to the land through the medium of the irrigation water. At various convenient spots on the tramway system there are mud or " scum " chutes below the track into which special rail-cars discharge the material into swiftly running water. The floor of the steeply constructed chute contains projecting hard rocks to break up the masses of mud as it is water-borne to the fields.

The rolling terrain and the nature of the soil, which is 9 in. deep on the average overlying porous shale, make it necessary to regulate with extreme care the slope of planting furrows, which are laid on grades ranging from 1 in 75 to 1 in 150. A few lines used as markers are set out in each field using a dumpy level, being marked by reeds at approximately 50-ft. intervals to serve as guides for the furrowing operation. The water from the supply canal at the top of the field is brought in by furrows called water lines spaced 200 to 300 ft. apart. These are cut by a tractor-drawn ridging plough to a grade of 1 in 300. The survey work required for the correct grading of planting furrows and water lines is only needed once in a complete planting cycle, and is well repaid by the protection afforded to the land by the careful regulation of the flow of water thus made possible. Irrigators are trained, and four of them on the average work 1 cusec of water, each watering amounting to about 4 in.

It is not possible to deal exhaustively with the subject of water supplies in a work devoted to a particular crop, but the outline given describes briefly the more important points. Detailed information can be found in various publications, some of which are mentioned in the appendix. Hydraulic engineering, a branch of civil engineering, is highly specialized, and for anything beyond quite small and localized projects, it will be wise to consult an authority on the subject.

CHAPTER 14

MECHANIZATION OF SUGAR-CANE AGRICULTURE

Definition The term mechanization implies the use of implements with

steam, internal combustion engine motor, or electrically-operated tractive and power units. In its broader sense, it includes a range of animal-drawn machines for the operations of land preparation, cultivation, weeding and fertilizer application. Consideration of mechanization here will be confined to the use of mechanical power for cane farm work.

Evolution The evolution of modern systems is traceable to the expansion

and intensification of production of the cane on the one hand, and the replacement through successive stages of small mills driven by animal, wind, water and even manual power, by larger and ever larger multiple units worked by steam and electricity, and dealing with the cane from many thousands of acres of land. Earlier methods depended on a plentiful supply of docile hand labour. All work on the land, from initial clearing, to reaping and loading were thus performed. Animals were used for conveying the cane from field to mill. Donkeys and mules carried packs of cane and cattle hauled carts. High value was attached to farmyard manure and chemical or artificial manures were unknown. The slave trade of the eighteenth and early nineteenth century kept many of the sugar plantations of those days well supplied with labour, but its abolition in various countries at different times made it increasingly difficult for cane planters, in common with others in tropical and sub-tropical countries, to obtain sufficient workers for their needs. Thus the field labourers, both male and female, with their heavy hoes were supplemented to an increasing extent by animal-drawn ploughs and other cultivation implements, most of which were designed originally for farming practice in

253


Britain and Europe, and in later years in the U.S.A. The application of steam power to the major land operations of ploughing, harrowing and draining soon brought about the limited use of heavy steam engines and their cumbersome cable-hauled implements on some of the larger sugar estates, so that by 1863 the age of mechanization of sugar-cane planting was fairly started by the importation of the first steam ploughing set into Antigua. Though this was followed by others in St. Kitts, Jamaica, Trinidad and elsewhere, it is clear from the records that they were not in all cases successful, some of them being discarded for many years and brought into service again at the turn of the century. Working in the heavy clay which is characteristic of many fertile sugar-cane lands, ploughs stalled, turned up the subsoil, and in 1906 in Antigua could only be used for work across the beds. The result was that drains were filled, with disastrous results when rain fell immediately afterwards, although the land was subsoiled twice to a depth of 2 ft. The ploughed area became completely waterlogged and was only reclaimed at great cost and trouble. The importance of maintaining the drainage system in working order at all times was recognized, and though expensive at the time the experience has paid handsome dividends since I Although they were used for many years and in some instances were not discarded until the diesel-engined track-type tractor became available, there was continuous investigation with the object of devising more efficient power cultivation methods. This work proceeded rapidly during the closing years of the nineteenth century and gained impetus in the twentieth by the development of the internal combustion engine for farm purposes.

The wheeled internal combustion-engined tractor made its appearance early in the century. Motor tillage for sugar estates was advertised by an Edinburgh firm in 1904. The iron-tyred wheels of those days limited both the life and usefulness of these prototypes of the modern rubber-tyred machines which now perform a variety of work formerly done by animals, as well as numerous new tasks made possible by modern mechanical aids. The cable ploughs with their steam engines, succeeded by similar diesel-powered units are now replaced by track-type and rubber-tyred wheeled tractors with hitched or direct coupled implements, while hydraulic gear for lifting on the turn and depth control of

MECHANIZATION OF SUGAR-CANE AGRICULTURE 255

cut is standard. The advantages of pneumatic tyres for sugar estates haulage vehicles were recognized about 25 years ago. They have come into increasing use until now by far the greater portion of the cane crops which are hauled over roadways move on rubber. In parallel with this the designs of cane carts and tractor trailers have been improved.

The Track-Type Tractor The track laying tractor owes its development to the needs of

wheat harvesting and log hauling in the U.S.A. It evolved from the steam traction engine; in fact, the first track-type machine built at Stockton, California, in 1904, was steam-driven (Fig. 29). The track shoes were of wood, the drive being by sprockets and long, exposed chains. An interesting feature of this and later models for some years was the tiller wheel which persisted until about 1915, even with the machines powered by internal combustion engines which made their first appearance in 1908. One of these was in use on a sugar plantation in Hawaii in 1912-13 (Fig. 30). The first diesel track-type tractor appeared in 1931. It is interesting to find that the steering clutch device was patented in 1891, some years before the track-type tractor made its appearance.

The track-type tractor rapidly came into favour for agricultural purposes, and stimulated the design of implements suited for use with it. The U.S.A. led in these developments, and soon a range of machines was available with implements designed to be used with them.

The diesel engine as a power unit for agricultural tractors, has proved one of the great advances of modern times in its application to all operations on and immediately below the surface of the land which involve the movement of earth, the pumping of water, the application of sprays, the haulage of crops, well sinking, mole draining, excavation work, and numerous other activities. In parallel with the improvement in the design and range of mobile power units and the implements used with them, are the advances made in wheeled tractors, which are now complementary to the track-type machines, each having its special sphere of usefulness, and both being suitable for certain purposes. This feature has developed mainly from the application of rubber tyres to land


work, as well as from improvements in the machines themselves. All this progress has been brought about by research in many branches of science and the application of its results to industry, work which is still continuing. The first world war which saw the introduction of the tank was directly responsible for much improvement in design and performance of the track-type tractor. Between the wars American manufacturers, with their enormous home market, and immense schemes of development involving earth movement, produced a wide range of ever improving machines with a variety of specially designed equipment. In the United Kingdom progress was not so marked though wheeled-and track-type machines of comparatively low power were made for general agricultural purposes. The second world war of 1939 to 1945 brought into use every available type of track-layer and equipment in enormous numbers, and further stimulated and extended the general use of this type of tractor. During the past 10 years progress in the tractor field is remarkable. British as well as American manufacturers now produce a range of machines from miniature to high power with an extensive variety of equipment and implements.

Aircraf t

The use of aircraft for special purposes on sugar estates is a modern development, though it is recorded that the U.S. army carried out experiments on the control of insect pests by aeroplane in the Philippines in 1925. Aerial photographic surveys for civilian purposes were being conducted in East Africa in 1928. Improvements in technique and equipment since then are remarkable, so that now it is possible to obtain a degree of accuracy comparable with surface surveys at a very much lower cost. In Florida the distribution of poison bait for rats is effected from the air, and cane areas are inspected. The application to crops of insecticides and fungicides by specially equipped fixed and rotating wing aircraft is rapidly increasing in other countries. Chemical weed control in the same manner is a likely possibility.

Development and Effect of Mechanization The sugar-cane planter to-day has a choice of machines suited

to his particular needs, whatever the size of his cultivations may


be. Mechanization of field operations from initial clearing of the land right through to transport of the reaped cane is now commonplace, with the exception of reaping, which, however, is now done by machine in some countries. On the older plantations the change from hand labour and animal draft to the use of mechanical power has been gradual in the initial stages and more rapid during the past 15 years. Recently established sugar-cane areas planned on more modern lines have been highly mechanized from the outset. Thus, parts of the British West Indies and the Everglades region of Florida may be contrasted in that way. Though manual and animal power is still extensively used on peasant cultivations and to a comparatively small extent for certain work on plantations in some countries, mechanized sugar-cane farming has become standard practice in all territories where the crop is grown on an extensive scale. The former limitation on production and expansion imposed by the labour factor has disappeared, and even when labour is reasonably plentiful, mechanization of sugar estate operations has proved of advantage to planters and workpeople alike. Social advances in colonial sugar producing countries have brought about great changes in the outlook of plantation workers. Many of the operations entirely performed manually in the past have become increasingly distasteful to labour, and though the bustling activities of the cane harvest are in most places cheerfully and energetically undertaken, the necessary preparation for planting and the cutting and cleaning of drains are unpopular. Indeed, after a natural and understandable resistance to the introduction of new methods, the incursion of machines has rapidly been welcomed, and their advantages appreciated even by the humblest worker. The speed and efficiency brought about by mechanization removes the most serious anxiety of the planter—that of getting the work on the land completed at the most favourable time, as well as in the harvest or " crop " time, of moving the reaped cane to the factory with the minimum of loss in quantity and quality.

The increasing use of farm machinery has had an inspiring effect on all concerned. The ambition of workers has been stimulated, and the desire to become the operator of a machine instead of an unskilled labourer is widely apparent. Workers of all classes are benefiting from the increased and more efficient production brought about by cane estate mechanization, and the


land devoted to this crop is giving markedly better returns. This factor is of the highest economic and social importance in view of threatened world shortage of food, which amongst other things makes it vital to raise the productivity of the land to the highest possible levels, consistent with the maintenance of soil fertility, in all agricultural industry. Methods vary considerably in detail in accordance with local conditions, including the available supply of labour at certain periods of the year. The effect of mechanization in bringing about increased production is remarkable, a point discussed in more detail later.

TYPICAL LABOUR REQUIREMENTS FOR PRODUCING SUGAR-CANE IN LOUISIANA U N D E R NON-MECHANICAL AND COMPLETELY

MECHANIZED CONDITIONS

Operation

Planting : Ploughing rows Opening furrow Cutting seed cane Hauling and drop

ping cane Covering Rolling Opening drains

Total

Growing : Cultivating

Fertilizing

Hoeing Opening drains Cleaning ditches

Total

Harvesting : Cutting Loading and haul

ing

Total

Total, all operations

Non-Mechanised

Equipment

2-mule plough 2-mule plough By hand

2-mule wagon 2-mule harrow 2-mule roller By hand

2-mule plough or cultivator

By hand

By hand By hand By hand

By hand

2-mule wagon

Hours per acre

9.0 1.2

13.2

7.0 1.2 0.6 1.8

34.o

30.0

2.7

24.5 7-5 6.3

71.0

70.0

26.0

96.0

201.0

Completely Mechanized

Equipment

Tractor plough Tractor plough Cane harvester

Tractor wagon Tractor harrow Tractor roller Tractor plough

Tractor rotary hoe and disc cultivator

Tractor box and disc

By hand Mule plough By hand

Cane harvester Loader and tractor

wagon

Hours per acre

1.4 0.6 0.6

6.5 0.6 0 . 2 1.2

11 .1

5-o

0.8 9.0 3-6 4.0

22.4

6.8

16.6

23.4

56.9


The decision of a planter as to the nature and extent of mechanization he will adopt, and the rate at which he can introduce mechanical methods will be influenced by personal and material factors. Diminution or irregularity in the labour supply can only be met by the use of machines unless production is to decline. Fertile land thus becomes neglected, as if cane planting is impossible it is highly improbable that any other crop can be profitably grown. In countries where alternative and more attractive opportunities have developed for employment, labour soon displays a desire to leave the unattractive work of the cane field, a condition which has become increasingly manifest. Wages have risen at a greater rate than sugar prices, which of course govern the value of cane, wi th the result that the more efficient operations made possible by mechanization become very attractive to the planter. For a given output, the number of persons employed on the land is remarkably reduced by mechanization, an advantage which has the further effects of reducing cost of supervision, and of the special provisions grouped under the general head " labour welfare."

Planning for Mechanization As with all other phases of the industry, careful planning is

required to decide the types of equipment to be used, and their sizes and numbers. Consideration of these matters should include :—

(a) Climate and weather. (b) Soil. (c) Seasonal requirements of the crop. (d) The planting cycle. (e) The total and subdivisional areas of land to undergo

various treatments. (f) Estimated weights of crop and materials to be moved. (g) The topography of the plantation. (h) The cost a n d availability of tractor fuel. (t) Maintenance facilities. (j) Supplies of spare parts. (k) The general requirements, other than those immediately

related to sugar-cane agriculture, which can be effectively met by mechanical devices.


The range and variety of these now available render it essential to integrate carefully the complete mechanical equipment of a farm in such a manner as to provide for all services which can be efficiently performed in this way and to avoid as far as possible acquiring major items which are only occasionally needed.

There are three types of organization to be considered, each subdivided into that for non-irrigated and irrigated crop production. In discussing the establishment for each of them, it is assumed that the highest possible degree of mechanization consistent with efficient plantation operation is desired. The main types may be described as :—

(a) An entirely new project. (b) An existing cane plantation with an extensive area of un

developed land suited to the crop. (c) A cane farm or plantation having no additional land available.

How then will the governing factors outlined affect these typical groups ?

New Projects and Extension A new project and the extension of an existing one will require

the clearing of the land; the excavation of main drains ; the alignment and grading of roads and field intervals ; the movement of constructional material for bridges, culverts and other works. Under high rainfall conditions it will only be possible to use heavy machines on the land for limited periods each year ; while the inclusion of an irrigation scheme will involve additional operations for canals and main irrigation works, but with much longer dry seasons, relatively less equipment will be needed.

The whole of these operations can be efficiently and cheaply performed mechanically and at much greater speed than by manual labour. The equipment is expensive, but much of it is used for normal work on a large plantation. The decision whether to purchase will largely depend on existing and future needs, and the availability of machines which can be hired. In some instances work of this nature can be done by contract. With large schemes extending to areas of the order of 5,000 acres upwards for new projects, and 1,000 acres for expansion jobs, it is best to acquire what is needed and engage the operators to work it so as to have the whole project under control.


Clearing of Bush and Woodland Clearing of bush, with medium sized trees up to a foot or so in

diameter is readily carried out by heavy crawler tractors and dozers. These machines will uproot and push the trees over, dealing with scrub and undergrowth. Trees too big for the dozer may have to be felled or dynamited. Possibly some stumps will need to be excavated and pulled out by a tractor and wire rope. Useful trees can be sawn into convenient lengths by portable power saws. All useless material is pushed by the tractor-dozer into large heaps, and burnt at a convenient time. When the surface has thus been cleared, the same type of tractor is used with a heavy rooter to break up and pull out the roots left in the soil. At this stage survey details will be rechecked and amplified where necessary on the results of which the field layout, including drains, irrigation ditches if needed, field intervals and roadways will be finally settled.

Any levelling of land can be done by the dozer or by graders, after the rooter has completed its task. This field levelling or grading may be left until after the first ploughing. It is not necessary unless surface irrigation is to be practised, and even then is only carried out in land with deep soil and slight differences in level, as there is risk of destroying fertility by cutting into infertile subsoil.

Roadways Roads and field intervals are formed with the same machines

using first the dozer. Modern graders are self-powered, being mounted on the same wheeled frame as the engine which moves them (Fig. 53). Formerly they were separate implements hauled by an independent tractor. The angular setting of the grader blade is highly important. The machine is designed to finish the surface of roadways and embankments by skimming or scraping the surface and moving loose earth to the side. The angle made by the blade to the fore and aft centre line of the machine should be greater than the angle of repose of the soil in which it is working, so that the loose soil flows along the blade and is deposited at the trailing end. If the angle of setting be less the soil will be carried in a forward direction, and unless there are depressions in the line


of movement, will have to be released by lifting the blade or adjusting the angle. The former results in heaps of earth left in the track, which will need to be moved.

Embankments, Drains and Irrigation Canals Graders also can be used for the formation of embankments

and the excavation of drains of limited width and depth. In the former case the blade is set in a side position the bottom end leading, the angle adjusted as described and the earth moving upwards along the blade and being deposited along the line of the trailing end. Though not designed for drains and irrigation ditches, graders have been successfully used for making them in more easily worked soils. They are better fitted for widening an existing cut than for carrying out the whole of the construction. Smaller drainage and irrigation channels are constructed by tractor hauled furrowers fitted with side blades or sweeps to move the excavated soil away from the cut. These machines may differ only in size from those used for ordinary field operations, though heavy machines of special design working on the same principle are extensively used. For deeper cuts of limited width, powered ditchers with excavating buckets mounted on a large revolving wheel, or on a heavy chain belt carried by a rear frame, are available. They are more suitable for making channels for tile drains, or for water pipes, though they have been used with success for surface drains in cane fields.

Larger channels for main drains and irrigation canals are excavated with drag lines and power shovels. The bridges and culverts required to over-pass drainage and irrigation channels must be of adequate strength to support the heaviest load which has to pass over them.

Transport Transport equipment for materials required to construct small

bridges and culverts, tramways, fences, the lining of irrigation canals and other works and for removing debris not otherwise disposable from the cleared land, should be stricdy related to the recurrent field operations for normal cane growing. If these include the use of mobile cranes, as they do in many places, loading and unloading will be made easier.


It will be realized that with few exceptions the machines mentioned are standard equipment for mechanized sugar-cane agriculture, a point more clearly demonstrated by a summary.

TRACTORS, IMPLEMENTS AND THEIR WORK

Machine and Equipment New Project or Ex- Ordinary Recurrent tension Operations Farm Operations

A.i. Tractors :—Heavy wide- Required for all 80 to 120 h.p. re-track-type 80 to 150 draw- heavy work. quired for the bar h.p. with diesel heavy work of engines, fitted with power ploughing and take-off and lifting gear ; subsoiling. winch and wire rope. Canopy over driver's position. Automatic recording clock. Lighting.

2. Angle Dozer. Bush clearing, Occasionally used levelling, road for similar pur-forming earth poses ; a lighter movement. type may suffice,

refer. B.2.

3. Rooter. Breaking up and Not normally bringing to sur- wanted. face of roots, loose rock and stones. Opens up the subsoil, and facilitates ploughing.

4. Heavy draining plough Subsidiary drains and minor irriga-(Cuthbertson type). tion canals.

5. Multiple disc or mould- Ploughing to a depth of 12 to 14 in. board ploughs.

6. Heavy subsoilers (pan- For subsoil work to a depth of 21 to breakers) or knifers. 24 in.

7. Moling plough (in For opening of mole drains, localities suited to mole draining) for 6 or 8 in. mole channel. s

iiliSik


B.1. Tractors:—Medium 35 to Required. Required for 60 drawbar h.p. and low- general purposes. powered under 30 drawbar h.p. track-type, with diesel engines, canopy, recording clock power take-off, hydraulic lift and lighting. Medium sizes should have winches and wire rope.

2. Angle Dozers. Lighter work of earth and material moving; bed formation.

3. Disc and Mouldboard Ploughing, ploughs.

4. Subsoilers. Light machines, useful. Single, twin or three panbreakers working to 21-in. depth.

5. Furrowers. For cane furrows, drainage work and field ditches.

6. Cultivators, rigid and For inter-row cultivation and weed-spring toothed, sweeps, ing. Preferably used with a hydrauli-chisellers, disc harrows. cally controlled tool bar mounted on

a " U " frame with fore ends carried by bearings on tractor frame to give maximum lift.

7. Steel-bodied rubber-tyred General material Cane and general trailers. transport. transport.

Trailers should be designed with open bodies for cane, and adapted for other material as required.

8. Centrifugal pumps port- Water pumping Fire control, able type, with suction and from foundation Temporary delivery piping. work. pumping to

assist drainage.

C.1. Tractors:—Wheeled, General light fast haulage work, with rubber tyres, diesel or Furrowing, spraying, inter-row gasoline engines, hydraulic cultivation work, lifting gear for tool bar, power take-off, lights, recording clocks. Implements and other equipment


will depend upon farming methods, soil and climatic conditions. For working under heavy conditions, twin rear wheels are desirable. High clearance machines are needed for the bank and furrow planting system. Width of track should be adjustable within limits, the normal being 6 ft. In some cases the three-point suspension is preferable to the normal front axle which gives the same width of tread to front and rear wheels.

2. General cultivation tools, Lighter types of land cultivation, including ploughs, adapted to the particular make of tractor.

3. Cane planters, with fur- Cane planting, rower, planting box and chute, fertilizer attachment, furrow closing blades or discs and roller.

4. Miscellaneous machinery: An extensive and useful range of circular saw, post-hole such equipment is available. Selec-borer, blade terracer, tion should be made with reference scoop, grass mower, crane to suitability for attachment to the loader. tractors used, and local require

ments.

5. Cane carts or trailers, Required for road haulage of cane, steel bodies, low hung on Not needed if portable tramway steel axles and 4 rubber- tracks are used. Can be fitted with tyred wheels, large at rear, temporary linings to the body, smaller in front; specially made of wood or metal, for trans-stiffened body for rough port of miscellaneous material, work; flared sides, draw- The carts are best suited for load-bar ; gooseneck to enable ing and carrying cane, which is front axle to turn under lifted in chained bundles. the body so that the cart can be turned round in its own length ; arranged


for coupling in trains. Boxes for loading chains are useful. Machines far Special Work Nature of Work Performed Usually self-contained units adapted for movement and operation under their own power.

D.i. Traction Ditchers, and For cutting trenches for the laying bucket excavators. of water pipes, tile drains, and for

irrigation and drainage canals. Various types and makes are available suited to particular conditions of working and different widths and depths of cut.

2. Power Shovels. For excavation of large canals, deep foundations, and quarrying. Loading of earth, stone, coal and similar material.

3. Draglines. For construction and cleaning of large drains, irrigation canals and waterways. Used with grabs, they can be used for loading and unloading cane and miscellaneous material.

4. Transport Cranes. Different sizes and lifting capacity. Widely used for cane loading in the field.

5. Power Grader. Construction and maintenance of earth roads, field intervals, cambered beds, embankments. Useful for part construction of large earth drains and canals.

6. Rotary Hoes. (Rototillers For inter-row weeding and cultiva-and similar implements can tion work under favourable condi-be used as required with tions. any suitable type of tractor.)

7. Concrete Mixer. Bridges, culverts, main irrigation canals, and miscellaneous construction work.

8. Dump Truck. A convenient form of self-discharging transport.


Comparative Tractor-Power Requirements for High and Low Rainfall Areas

Plantation in high rainfall area (80 to 90 in. per annum) with high proportion of heavy land, and

widely varying lighter types. Cambered bed system with drains on 22 to 24 ft. centres. One-fifth of cane area capable of being gravity irrigated in about 16 weeks yearly. Average planting cycle 4 years. Area reaped annually 7,250 acres. Total area in cane, approximately 10,000 acres. Annual replanting 1,750 acres fall plants, 400 to 600 acres spring plants. The area displays great variations in soil types and level of fertility. Annual average production of cane per acre from reaped area has ranged from 31 to 38 tons. Harvesting season limited by weather conditions to ± 135 days. A considerable amount of land work is done by manual and animal power.

Heavy Track-type Tractors 1 to 1,250 acres. ± 120 h.p. Used for ploughing, subsoiling and

subsidiary drainage for land to be replanted. Tractor rating provides for 1 reserve machine for the whole of each area.

Medium Power Track-type 1 to 1,250 acres. Tractors ± 40 h.p. For cultivation. Wheeled Tractors, rubber-tyred, 1 to 1,250 acres. with cultivation implements ± 35 h.p. Low Power Track-type Tractors 15 total number. ± 25 h.p. For haulage of cane trailers between

field and interval in the more difficult areas.

Wheeled Tractors, rubber-tyred, 15 total number. for cane haulage Power Graders:—Light (or 1 to 1,250 acres. detachable machines for use For reforming cambered beds. behind a medium tractor) 8-ft. blade. Power Graders :—Heavy, 12-ft. 2 for whole area, blade. Roads and intervals.

Irrigated Plantation in low rainfall area with high proportion of easily worked free draining soils, and some heavy clays. Mechanical work on the land usually possible for 8 or 9 months each yar. General land working conditions easier, except that heavy trash retards work in ratoon fields. Planting can continue over long periods, assisted by irrigation. Cane yields average 35 to 45 t.p.a. Harvesting season 140 to 180 days. More heavy and medium h.p. track-type tractors are used, there


being no need for low-powered ones as the terrain permits movement of heavier loads. The cropped and total areas may be considered closely comparable to the high rainfall plantation for the present purpose.

Heavy Track-type Tractors 1 to 1,650 acres. ± 120 h.p. Land operations are almost com

pletely mechanized.

Heavy Track-type Tractors 1 to 2,000 acres. ± 80 h.p. Used for ploughing, subsoiling and

subsidiary drainage for land to be replanted. Tractor rating provides for 1 reserve machine for the whole of each area.

Medium Power Track-type 1 to 450/500 acres. Tractors ± 40 h.p. For cultivation and cane haulage. Wheeled Tractors, rubber-tyred, 1 to 2,000 acres, with cultivation implements ± 35 h.p. Wheeled Tractors, rubber-tyred, 13 total number. for cane haulage. Power Graders :— 1 to 2,000 acres. Light (or detachable machines For re-forming cambered beds. for use behind a medium tractor) 8-ft. blade. Power Graders :— 1 for whole area. Heavy, 12-ft. blade. Roads and intervals.

The number, size and power of the various units will be determined by the extent and urgency of the work to be done. Smaller schemes of the order of hundreds of acres can be completed mechanically, and lower powered units with corresponding implements are available for most of the work. The desirability of relating the initial selection of equipment to the continuing needs of normal operation is obvious.

Preparation for Planting After the completion of these operations in new land, the later

stages of preparation, planting and cultivation of the crop follow the same pattern for all three cases, with modifications for irrigated land, and differences rendered necessary by variations of soil type, rainfall and topography. The present object is to discuss


mechanization rather than differences in practice which are dealt with in Chapter g. The usual sequence of mechanized operations is ploughing, subsoiling, bed forming and field draining. When necessary, furrowing, planting, inter-row cultivation and weed control involve the use of tractors. As a general rule these machines themselves move over the fields in the course of their work as contrasted with diesel engined cable sets which are employed to a limited extent in some countries. A wide range of tractors is available to choose from. They fall into two classes, track type, and wheeled with rubber tyres ; with models in each class differing in design, power, and related characteristics. Careful selection should be made in the light of the conditions under which they are to work, the periods of the year when work on the land can best be undertaken, and the amount of work normally to be done. Similar considerations apply to the implements which are to be used. Initial preparation of land for cane planting is heavy work requiring ample power for the implements used, and it is an advantage to complete it quickly, especially where the crop is grown under natural rainfall conditions.

Crawler or Track-Type Tractors For ploughing and subsoiling, track-type diesel tractors of 80

h.p. and upwards have proved their value, though in light, free-draining soils machines of lower power can be used. Track-type machines exert a surprisingly small pressure per unit area on the soil, while exerting high tractive effort.

TYPICAL GROUND PRESSURES OF TRACK-TYPE TRACTORS

Drawbar h.p. Pressure on Ground p.s.i.

150 6.5 120 7.9

80 6.3

55 6.2 35 6.5 25 5.2

Pressures quoted are for standard widths of track. Some makers supply machines with wider track shoes to order, and pressures are correspondingly reduced.


The track itself is laid on the ground by the machine, which moves over it, the portion in contact with the soil remaining stationary. Thus the tractor moves on a flexible support which is part of the machine. The track on each side of the machine is a continuous chain constructed of rectangular links each of which is capable of movement in the plane of the whole track which enables it to pass round the spockets of the tractor and to support the weight of the machine transmitted by them and by track rollers carried by an underframe. The track plates are fixed to the chain one to each link. Near the leading edge is the " grouser," a right-angled projection which provides additional grip on the land. The track plates or shoes are bored so that road plates can readily be fitted. Steering is effected by checking the driving wheel on the side towards which it is desired to turn, change of direction being brought about by the difference in t h e power applied to the tracks causing the tractor to swing round on the slower moving side. The effect is to bring about a difference in the rate of laying the track, which results in the turn. There are various methods of doing this depending on the make of machine involving one or both of the operations of partial or complete declutching and braking.

Considerations of Tractor Power A question often posed is whether it is desirable to concentrate

tractor power in a small number of high-powered machines, or to use more smaller ones, bearing in mind that for certain work powerful tractors are in any event necessary. The basic consideration here is the result of lost time caused by mechanical breakdown. It thus appears desirable, though not always economically possible, to have more machines than the bare requirements for the completion of work in the available time. The matter is related to servicing, overhauls and repairs. Modern tractors are highly reliable if these matters receive proper attention, though there is always risk of breakdown by mechanical failure, accident or faulty operation. Upon being satisfied that lower-powered machines can perform the work there appears to be an advantage in using them on the grounds that the effect of a tractor not capable of working must be judged in terms both of t ime and power, and not by time alone, bearing in mind that the implements


designed for use with a unit of given power cannot be effectively used with one of lower power. Moreover the capital charges continue at a higher rate during lost time for the more powerful machine. On the other hand the distance travelled over the fields to accomplish the same amount of work is proportionally greater for a low- than for a high-powered machine, but the small machines are more manoeuvrable, turn more easily at headlands, and are capable of faster movement when not under load.

As an example a comparison between machines of different power ratings, for conditions under which the smaller can operate efficiently, results as follows :—

Operating Requirements Apart from the implements needed, the auxiliary services and

equipment for tractors have to be considered. It is vital to provide all reasonable measures which will reduce lost time to a minimum. Obviously competent operators are the first essential, who are not only capable of high skill in using the machine and its implements, but of diagnosing faults, and effecting running adjustments. The latter should be limited by definite instructions so that major faults and breakdowns are corrected and repaired by special staff either in the field where that is convenient and possible, or in a well-equipped workshop. It is most undesirable to dismantle any but the very minor parts in the field. Operators should be supplied with essential tools, and regular checks on them should be carried out. Automatic recording of working and idle time should


be made for each machine by the special time clock recommended by the makers of the tractor, and operators should as routine be called upon to keep a log which amongst other matters contains brief explanations of unusual periods of idling. Lights should be standard in front and rear so that night working may be carried on under suitable conditions. Hydraulic and other lifting devices are referred to at this point in passing—they are discussed more fully later on. A power take-off is a modern device usually incorporated in the basic design of the tractor, enabling the engine power to be partly or wholly transmitted to some attached machine or implement. If the chassis permits the attachment of a winch and rope drum in such a manner as not to interfere with the ordinary work of the machine, it is an excellent thing to have one permanently fitted, drive being transmitted to it when necessary by the tractor engine. A few hundred feet of wire rope will enable the tractor to haul itself out of trouble or to pull other objects from positions which the machine itself cannot approach with safety closely enough for removal otherwise. For movement over hard roads the track plates or shoes should have road plates fitted, to increase the track-bearing surface and avoid damage to both tractor and road. In their absence the edges of the up-turned grousers on the plates provide the only surface contact. Road plates may be of steel, wood or hard rubber.

Movement on Highways Tractors of this type are designed for working on comparatively

soft ground, rather than on hard surfaced highways. If, therefore, it is necessary to work them on such surfaces, road plates, preferably of wood or hard rubber, should be fitted. For movement from one place to another at a distance over hard roads, it is wise to transport the machine on a specially constructed trailer hauled by a tractor designed for highway travel—usually a rubber-tyred wheel machine. In the case of the smaller compact farms with no main highways traversing them, this would not be necessary, but it is advisable in the circumstances described to avoid unnecessary wear and the heavy shocks caused by travel under power over very hard ground.

The desirability of high clearance track tractors has been urged for inter-row work, and though there is no inherent difficulty in


designing and building such machines, manufacturers have been reluctant to make them because of the wide differences in suggested track centre distances brought about by variations in the spacing of cane rows. Unlike wheeled machines, the width between tracks cannot be varied, and makers want to fix a standard which can be widely used before embarking upon their production programmes. The great improvements in wheeled machines during recent years have provided tractors capable of doing most, if not all, the inter-row work for which high clearance track tractors were proposed.

Wheeled Tractors Many makes and sizes of wheeled tractors with rubber tyres are

available, operating on petrol, vaporizing fuel, and diesel oil. Low and high clearance types, with single and twin rear wheels, wide or very narrow forecarriage giving almost a three-point effect, and hydraulically operated tool bars and lifting gear for implements may be used according to farm and field conditions. Though desirable, it is not always possible to decide upon a single type for all work. Some of the field requirements involve high clearance machines, and while these can be of general service, low clearance models are more suited to open field work and haulage. No rule of choice can be given other than the basic considerations of ample power and suitability for the tasks to be performed. Obviously a triple track machine is useless for any field work after the cane is planted, since the front wheels as well as the rear ones must run between the rows and not over one of them ; while a low clearance machine has only limited use when the cane is in its early stages of growth if damage to the plants is to be avoided. It has been proved that tractive effort for a given power depends mainly upon the weight carried by the driven wheels. Tyre size and tread design are important in making this weight effective. Certain types of tyre can be water loaded, a practice found to be of additional advantage.

Driving Conditions and Equipment Driving comfort for operators is of prime importance for all

tractors whether track-type or wheeled. Close attention to this is well rewarded by longer tractor life, greater freedom from break-


downs, fewer accidents, and higher driving efficiency, because of the lesser strain on drivers. Support for the small of the back, and means of reducing the eifects of shock are needed, the design being such as to provide firm comfort at the sides and back as well as the seat, while giving ease of access to all controls and sufficient freedom of movement for driving purposes. A canopy over the driver's seat is a great advantage for all larger machines.

With the exception of the winch and drum, supplementary equipment should be as for track-type machines with the addition of a warning device mainly for use when the machine is working on roads and field intervals at speed.

Implements—Ploughs Variety in design of implements for each land operation is

greater than that of the tractors with which they are used. It may be asserted that all standard field work can be readily provided with tools to perform that work efficiently under the full range of conditions encountered, each unit being adapted to particular requirements. Individual choice can be exercised as to type and make for each job, and the merits of these provide topics for discussion by users. Among such subjects are the relative advantages of mouldboard and disc ploughs. Both are extensively used and give efficient service; and each has its place in the sequence of land preparation.

Mouldboard ploughs are used in soils free from major obstructions such as roots and stones. Disc ploughs can be used in these soils, as well as under conditions where those things are present. The mouldboard plough leaves the land looking neat and well ordered, while the disc causes an uneven broken surface of irregular clods and soil masses. Bad work with the mouldboard is readily visible; not so with the disc, though both produce the same effect when efficiently used in suitable land. An advantage of the disc plough as compared with the fixed ploughshare is the lower friction between the turning disc and the soil.

Mouldboard ploughs for the heavy work of deep ploughing have multiple shares, designed to turn the soil over to the depth required, the number depending on the tractor power used and the nature of the soil. The main frame and plough beams must be of adequate strength, and rolling coulters are preferable to the


knife type. Notched rolling coulters will more easily cut through surface material such as trash and weeds which might otherwise impede and clog the plough. Various types of tractor hitch are used, a very satisfactory one being a multiple linkage which allows of relative movement of plough and tractor in any plane. This enables a lifting device to be used so that the plough is taken out of cut at the edge of the field, lifted clear of the ground while the turn is made, and put into cut for the next run. This may be an " A " frame mounted over the tractor carrying a grooved pulley over which runs a wire rope attached at one end to the plough frame, and operated either by a drum which can be rotated by engine power in either direction, or by a hydraulic system.

Disc ploughs are of two types—those in which the mouldboards of multiple furrow ploughs are in effect replaced by large saucer-shaped discs (Figs. 31, 32), and those having two or four gangs each carrying a number of such discs (Fig. 33). The former are made with one disc, or two or more in echelon according to the power of the tractor by which they are hauled. Each disc cuts a separate furrow. Four gang machines with 24 x 28-in. diameter discs in groups of 6 to each gang weigh about 4 tons and are designed for use with powerful track-type tractors. Various makes with discs differing in size and number are available. The two leading gangs each turn their furrows outwards, while the discs on the rear gangs turn inwards. The effect is to break up and turn the soil to a depth of 12 in. with the maximum set leaving no appearance of lined furrows as with other types. The setting of the gangs can be varied from no cut, with the discs riding the surface, through stages of increasing depth of working to the maximum, the plough being thrown in and out of cut by control from the tractor. Lighter machines are available for lower powered tractors. Notched discs are an advantage as they cut through weeds, trash and other vegetable (plant) debris more easily, enabling this type of machine to work under conditions where mould-board ploughs would become fouled by loose material such as dead cane leaves on the surface of the land. The multiple gang machines, with their variable adjustment can be used first to cut through the cane trash, then to plough to maximum depth and finally to break up the clods by working at an intermediate setting. The three traverses over the field add to the cost, which may,


however, prove worth while when it is desired to complete the preparation of the seed bed quickly. Mouldboard and disc ploughs are available in a range of sizes suited to corresponding tractor power and their selection is governed by similar considerations to those discussed on p. 270.

Subsoil Ploughing Subsoiling, or knifing as it is sometimes called, is carried out in

land where the subsoil needs shattering to a depth of about 21 to 24 in. from the surface to improve drainage and aeration. The machines used have strong frames on which are mounted heavy tines, blades or standards, usually terminating at the bottom in a shoe projecting forwards. The whole, or the toe of this is renewable when worn. The blades, knives or tines—whichever term is used, are bolted to the main frame in such a manner that excessive strain caused by unusual obstructions in the soil ruptures the shear bolts and enables the knife to swing backwards and upwards, thus avoiding damage to the implement. The main frame is of heavy construction carried by two large land wheels, one at each side, with quadrant lifting gear controlled from the tractor seat. The machine can be set to work at different depths and is pulled into and out of cut at will when moving. While this description refers to a particular design of subsoiler or " panbreaker " the principles of construction and operation are generally applicable.

Rotary Plough In deep alluvium or other deep soils free from large stones and

tree roots, the gyro-tiller performs in one operation the combined work of ploughs and subsoilers to a depth of 20 to 24 in. The machine is built as a single unit with a powerful diesel engine to provide for movement over the land surface and to drive the rotating tillers mounted behind. The latter are two heavy circular heads to which are bolted a number of skyves or tiller blades, forming a rotary plough. The tiller unit is mounted on a shaft rotated by the tractor engine. The shafts are set at an angle to the vertical so that the rotation of the head and skyves is in an inclined plane. Two are fitted to the machine rotating in opposite directions, with the skyves of one passing between those of the other on their inward sides. Two bolts, one of which is a shear bolt, fasten each skyve


to its head, so that as with knifers a heavy obstruction does not damage the machine. The frame on which the tillers are carried can be raised and lowered hydraulically, the same means being used to control the depth of working and keep it uniform. The gyro-tiller operates by a combination of the forward movement of the machine as a whole, and the rotation of the tillers, which shatter the soil as they pass through it leaving it in a thoroughly tilled condition without altering the relative position of the layers of soil. The sequence of movements is first the forward movement of the complete machine and the starting up of the tillers, followed by the gradual lowering of the tiller unit, each of the two members being in rotation, to the required working depth. The forward motion continues as does the rotation of the tillers until just before the headland turn when the rear unit is lifted clear of the ground with the tillers still turning. The tips of the skyves pass through the soil in a spiral course, with a trace similar to that of an extended spring parallel with the ground surface and having its lowest part at a depth of 20 to 24 in. The skyves or blades cut through the soil within this space, their traces being similar to a closely twisted flat ribbon. Large machines have a working width of 11 ft. With this machine a high proportion of the power developed by the engine is transmitted to the tillers and so applied to the soil, as contrasted with ploughs and subsoilers of the types previously described, which derive their effect on the soil from the forward movement of the tractors which pull them. A single rotary plough of this type is used with a heavy track-type tractor, being driven by the power take-off. Raising and lowering is effected by a winch mounted at the forward end of the tractor with chains on each side passing over a jockey pulley and quadrant, and connected to the tiller frame which is hinged to the rear of the tractor.

A great variety of implements is available for the operations of weeding, inter-row cultivation and weedicidal spraying. The control of weeds by the use of herbicides has in many instances made it unnecessary to perform the work of inter-row cultivation which was essential in weeding of the cane. Rotary cultivating machines such as the rotary hoe and the Rotavator have come into prominence during recent years, and are now extensively used for the final stages of land preparation prior to planting as well as for weeding and inter-row cultivation. The latter machine is directly


attached behind a tractor. It consists of a number of blades of special design mounted on a central shaft which is rotated by the power take-off of the tractor in the same direction as the movement of the tractor. The rotating hoes chop and loosen the soil to a controllable depth. When the machine is used in fields which have been reaped, the rotating blades cut cleanly through the trash and incorporate it in the surface layers of the soil. By removing the middle hoe attachment the machine can straddle a row of young cane. The soil is thoroughly broken up but its structure is not destroyed.

Reaping The reaping of sugar-cane differs in major respects from that of

any other member of the plant family to which it belongs, or indeed from any other crop. It is desirable that the cane should be delivered to the factory mature, clean, free from tops, trash, dirt and other foreign matter and in every respect fit for milling. These characteristics are not always achieved with manual cutting, and are very difficult to realize when the crop is reaped mechanically. The conditions under which reaping is conducted vary widely, and include flat land with regular cane rows and few obstructions ; flat and rolling land with narrow beds and field drains at close intervals ; hillsides with cane rows following the contours; banks with intervening deep furrows ; and other field systems depending upon the soil, the terrain and the rainfall. Varieties of cane differ in their habit of growth, adding still other factors to the complexity of those which must be satisfactorily met if mechanical reaping is to succeed. Erect canes of regular growth are more easily dealt with, and free trashing of the stem is a great advantage. Some varieties, while giving good yields of rich cane have a spreading habit, and still others tend to lodge and offer a tangled mass to the human cutter and the machine. Neglect in early stages of the growth cycle results in weed infestation which offers still another objectionable obstruction.

It will thus be realized that cane reaping machines have to be designed to cope with the particular groups of conditions met with in the areas in which they are to work.

The Fairymead cane harvester, the successor of several proto-

F I G . 29.—The original track-type tractor, 1904.

[Photos by courtesy of Caterpillar Tractor Co.

FtG. 30.—An early track-type tractor, 1912 (as used in Hawaii, 1912-13).

FIG. 31.—Shugadise TD9A Plough.

Photos by courtesy of Ramonies, Sims & Jefferies Ltd.

F I G . 32.—Ploughing in Natal.


types, has been in commercial use in Queensland since 1940. Cutting one row at a time at the rate of 200 tons or more a day, it is mounted on a high clearance McCormick International Farmall tractor fitted with heavy duty tyres. The cutting blade is fixed, and the machine has few moving parts. It works well in erect cane which has been burnt prior to reaping, but is not designed for lodged or tangled growth. The cane is not individually topped, the topping device being controlled by one of the two operators so as to give an average result, which has been found satisfactory. The machine drops bundles weighing about 400 lb. along the row, which are picked up by grab loaders, of which several types are used including the " Castagnos." In 1945 a two-row machine was developed, mounted on an International Farmall. This cuts 400 tons per 8-hr. day, and drops bundles of ¼ to ½ ton. The larger unit working with 4 grab loaders and standard tramway cane cars is operated by 14 men, of whom 2 are on the harvester, 4 drivers for the loaders and 8 groundsmen who work the grabs and move the portable track. The machine can enter a field without any preliminary hand cutting of cane.

The Toft harvester is a self-propelled, three-wheeled machine, which cuts the cane by two overlapping rotating discs, 24 in. and 30 in. in diameter. The cane is moved up an inclined plane by endless chains, and the tops aligned by iron paddles attached to a moving belt. The cane is topped by a rotating disc, the tops being thrown off by the paddles. The cane falls into a two compartment container which can be rotated longitudinally to discharge the cane in bundles.

A new type of cane harvester developed in Natal, South Africa, under the auspices of the S.A. Sugar Association, is designed to work on sloping land, cutting, trashing, and topping one row at a time. Attached to a track-type tractor, it is operated by the power take-off, and can be worked on either side of the tractor. The cane is guided into the machine by two continuous claw-chains which can be brought together at adjustable heights thus gripping the cane near the top. A cutting disc revolving at 300 r.p.m. severs the cane at ground level when it is in an upright position, the gripping effect of the "zip-fastener" chains carrying it past stripping drums with spring-loaded tines which remove the trash. A topping device cuts off the tops and the cleaned cane is dropped

T


on to a receiving platform, whence it is transferred to the transport vehicle. The prototype machine has been tested with satisfactory results.

The Thomson " Hurrycane " Harvester (Fig. 43), which has been progressively developed during a period of more than 10 years of successful operation in Louisiana, cuts the cane at the top and bottom and leaves heaps on the field. The machine which is of 65 h.p. has 2 engines, one of which is used for propulsion. It is mounted on 3 wheels of which 2 are on one side so that the single bed of cane to be cut is straddled. There are top and bottom double gathering chains which collect and hold the cane as the machine moves forward. Both the lower rotating cutting disc and the topping knife are adjustable. The harvester operates at the rate of 1¼ acres per hr. and requires 2 men.

Loading and Transport There remain the operations of loading and transport of the

reaped cane to the factory, all stages of which can be, and in many places are, completely mechanized. Great variations exist in the methods and equipment employed. In some cases manual loading of hand or mechanically cut cane is practised, with mechanical transport conveying the cane afterwards. In others the hand-cut cane is both mechanically loaded and transported while some mechanical reaping machines are designed to deliver the cane to a road transport vehicle. The types of equipment used for the three methods vary considerably and can best be appreciated from a description of a typical example of each.

Manual Loading, Mechanical Transport (Figs. 46, 47, 48, 49). The cane left in heaps by the cutters is picked up by hand, and

loaded into the transport vehicle. Men on the ground throw small bundles of cane to one or more men in the vehicle, who roughly pack it, or when portable tramways are used, the men pick up and load the cane into the cars. Road vehicles of various types are used, ranging from 2- or 4-wheeled wagons carrying 3 to 5 tons to heavy motor trucks and trailers with a total load of 15 tons or more. The normal condition of the land during the cane harvest period largely determines the type and capacity of the vehicles

MECHANIZATION OF SUGAR-CANE AGRICULTURE 2 8 1

used. Dry firm ground in the fields enables trailer carts to be hauled in and out by tractors, and motor trucks to be used. Where transport vehicles are limited to these types, wet conditions render it necessary to carry lighter loads, or to load on the trace or interval at the side of the field.

Under widely varying conditions it has been found as a result of the comparative testing of various types of vehicle, that the most satisfactory for general conditions is a 4-wheeled steel-bodied trailer cart, with rubber tyres, having a capacity of 3 to 5 tons of cane (Fig. 45). The rear wheels, which carry most of the load should be large in comparison with the front ones. The body consists of an open framework of welded mild steel sections 8 ft. or more in length, the sides being flared and stayed to members projecting from the bottom. The length should be related to the size of rail truck compartment when loads are to be transferred to railway cars. The base frame is strengthened by diagonal pieces, and firmly joined to a gooseneck under which the front axle is mounted. This design of forecarriage enables the front wheels to pass easily underneath so that the cart can turn in its own length. The open floor should be as low as working conditions permit in order to reduce the vertical height to which the cane must be lifted during loading. Carts are connected by the usual drawbar and pin, the former being strongly constructed to withstand arduous working conditions. Semi-circular guards welded to the cart sides nearest the upper half of the rear wheels will prevent damage to tyres by projecting cane. It should be noted that loading by hand results in the cane being more compactly packed, or in other words the weight per cubic foot is greater than with mechanical loading. Similar weights of load, therefore, require different body capacities. Loose cane weighs about 25 lb. per cu. ft., equivalent to approximately 90 cu. ft. per ton.

Operating Procedure A 35 h.p. wheeled tractor will haul 4 to 6 of these loaded carts

over farm roads. The advantages of the type are strength, low weight in relation to load carried, and comparatively low cost. They can be individually weighed on a platform scale without disconnecting them from the tractor or from each other. Under dry working conditions the trailers can be taken into the fields, and


hauled out singly when loaded, " trains " being connected up on the interval or roadway. In practice it has been found better to use a small track-type machine for this part of the movement sequence, the mode of working under a particular group of conditions being as follows:—

Cane cut by hand and thrown into heaps. Cane to be carried to a railway loading station with transfer hoist having a capacity of 3 tons. Rail cars, 36-in. gauge, two compartments each 12 ft. long, maximum capacity 15 tons, usual load 10 to 12 tons. Distance from field to rail hoist 3 miles. Roads, maximum gradient 1 in 25. Transport equipment 18 trailers, each having 1 pair of loading chains; one 35 h.p. rubber tyred wheel tractor; one small track-type tractor. Drivers and labour as required.

The pattern of procedure is always to have trailers in the field being loaded so that field labour is kept busy, and to maintain the movements of the 2 machines so as to reduce idle time to a minimum. First the 18 trailers are taken to the roadway nearest the fields where cane is being cut. It is an advantage to have two adjoining fields operating at the same time. The crawler tractor moves the trailers singly or in pairs to points in the field where heaps of cut cane are ready for loading, taking them when required to other spots. As soon as 2 or 3 are loaded, they are drawn to the roadway, linked together and taken off by the wheeled machine to the hoist, where they are weighed and unloaded. They are hauled back to the field, by which time a full load of 6 carts should be ready on the roadway. They are moved to the hoist, weighed, discharged and returned in the same manner. For quick working at the hoist it is desirable to place the 2 chains in position within the body of the empty cart, so that they surround three sides of the loaded cane mass when the cart is filled. The chain hitch is then used to link the ends with the ring end of the chains lying on the top of the load ready to be engaged with the hooks of the spreader at the hoist. Experienced judgment will keep each load within the limit of hoist lifting capacity.

This system keeps 12 or more carts or trailers at or near the field, the wheeled tractor shuttling between field and hoist, with little idle time. In good weather, other conditions being favourable, a set of equipment such as that described can deliver 150 tons of cane in a working day to a hoist on a railway system or


direct to a factory. The key operation is the rate of loading, which if too slow will prevent the road tractor from moving full train loads, or keep it idling for considerable periods.

It is of interest to record actual observations on the hand loading of vehicles. The weight of cane for each lift was found to range from 16 to 30 lb. The time required to load a ton of cane into a trailer varied from 20 to 28 min., similar figures being recorded for motor trucks. The number of individual cane lifts per ton was from 95 to 114, in the case of tractor-hauled trailers, and an average of 76 for small motor trucks with a mean load of 3½ tons. These figures are indicative of the human effort expended in loading and should be considered in relation to the time occupied in the operation, quoted below :—

Total cane loaded 14,000 tons Average load per trailer 2.8 tons Average lifts per trailer 288 Time required to load one trailer 66.5 min. Number of men employed 4

Mechanical Loading and Transport

An example of this system is that used by the United States Sugar Corporation, Clewiston, Florida. The cane, cut by manual labour, is left in windrows, the gang of cutters working in almost a straight line across the field. Track tractors fitted with a forward rake consisting of long horizontal tines mounted on a frame, push the cane into heaps. Mobile cranes with grabs pick up the cane and load it into large trailer carts which are then hauled to a railway siding and discharged (Fig. 51). The carts are of the track-type as contrasted with the wheeled machines already described.

Mobile cranes used for this work are of various types, designed for use with particular makes of tractor. A disadvantage of their use for cane loading is that they pick up trash, earth and other foreign matter with the cane, which give rise to difficulties in the factory. They are speedy in action, and save man-power, which are highly important advantages in places where labour is in short supply.

The "Tournahauler" is a heavy duty, rubber-tyred cane haulage unit with a capacity of 40 to 50 short tons of cane. In


some areas of Hawaii this method of transport is replacing the plantation railways. The body is fitted with a chain net attached to one side and capable of being lifted by crane tackle at the other to discharge the load. Loading in the field is done by mechanical grabs. It is reported that one machine is capable of transporting cane over a one-way distance of 5½ miles at the sustained rate of 35 tons per hr., equivalent to over 9,000 ton miles in 24 hrs.

Another interesting development is the Portacana system first used in Cuba in 1949. The principle is the use of a detachable cane transport body with a three-axle drive truck. Movement on and off the truck is controlled from the truck body by a power-operated winch with steel cable mounted immediately behind the cab. The underframe of the detachable body is so arranged that it can slide off or on to the truck chassis. The equipment is used by sliding off the body by slacking the cable, moving the truck forward if necessary. Several bodies, or skids as they are called, can be spotted about the field and hauled back on to the chassis for conveyance to the factory.. The capacity is 5 tons per load, and it is reported that one power unit can operate 5 to 10 skids, working at an average rate of delivery of 15 tons of cane per hr.

Plantation Railways Tramway and railway systems for cane haulage range from

24-in. gauge light track with cars loaded transversely carrying about 3 tons, to standard gauge line using two compartment open cars with side discharge gates hinged at the top, capable of carrying 15 tons or more. Tramways and light railways only, with their auxiliary equipment, come properly within the scope of the present work. These can be used with portable track laid into the fields so that the cars are loaded in the field, being hauled to the permanent system by tractors, and thence to the factory by steam or diesel engines. The portable track units can be loaded by light cranes, which may also be used for cane loading in the field, and moved in cars over the track which can be lifted section by section behind the cars until the permanent line is reached. After reaching the next take-off point, the reverse procedure can put the portable line into its new position. Another method is to move the portable track by road trucks or tractor-hauled trailers (Fig. 52).


Some Pros and Cons It will thus be realized that all operations involved in the pro

duction of sugar-cane can be performed by mechanical means. Some are more difficult to deal with in this manner because of unfavourable local conditions, while in some circumstances it is more convenient to use manual labour and animals. The present trend is in the direction of further and more varied mechanical work. Mechanical methods are now successfully applied where in recent times they were considered impossible, and active development of new machines and methods is in progress. Investigations of the effects of replacing animals by machines, with the resultant reduction or entire disappearance of farmyard manure formerly applied to the land, have failed to disclose any harmful effects. Indeed it has been clearly demonstrated that under proper agricultural systems, mechanical methods produce better crops, while they certainly maintain, and in many cases help to improve, soil fertility. Assertions are sometimes made that the movement of tractors over the land has the harmful effect of packing the soil. Any temporary condition thus induced is immediately corrected by the action of the implement hauled or worked by the tractor. Where light tractors are used with non-cultivation equipment, sprayers for weeds, for example, there is no danger so long as the soil is in fit condition for movement over it. In any event, the destruction of surface tilth by track-laying and wheeled tractors is negligible compared with that caused by animals and labourers under similar field conditions. An important principle is to reduce movement over the land to a minimum when the major initial preparation and planting of the cane have been completed and until the crop is ready to be reaped.

Combined Operations Future developments are possible in the combination of two or

more field treatments now performed individually ; the omission of certain operations by modifications in others; the more effective use of tractor power ; and the use of electricity. It has been shown that there should be the least possible movement of machines, men and animals over the land after planting. This is in the interests of preservation of soil tilth. For reasons of economy, all movements should be kept down to a limit consistent with soil


and crop requirements ; and much can be done in this direction by more careful attention to the practical needs of sugar-cane production, rather than by a slavish adherence to complex systematized practices. There is still need for intensive investigation of the minimum safe cultural requirements of this crop, the term " safe " being used in the sense of general protection of the interests of the soil, the crop, the equipment, and the planter. Minimum requirements mean, not the least possible amount of work, but the nature and extent of the operations consistent with profitable returns and safety as just defined. One of the causes of excessive effort is the separation of types of work which could be carried out together. Thus furrowing, planting and manuring, still largely done by three distinct operations, involving three separate movements over the land, have been successfully combined. Still another treatment, that of applying weedicides, can be given at the same time by adding a low volume sprayer to the equipment of the planting machine. Subsequent weed control treatments would need other methods as will be seen.

Possible combinations of other operations are trash comminution, ploughing and harrowing; trash cutting, light cultivation, fertilizer application, and making an irrigation furrow; both groups being applicable to fields just reaped, with cane trash left on the ground. The former would result in the preparation of a seed bed for a green manure crop grown before replanting the land with cane; and the latter would be used to assist ratoon growth for fields to be kept in production. The trash left after reaping interferes with cultural treatment for the benefit of the succeeding crop, whether replanting or ratooning is to be conducted. Fields can be cleared of the trash by careful burning, a practice often necessary to enable work on the land to proceed without delay. If left for a few weeks without burning, some rotting will take place, and though the breaking down of the material will be incomplete, ploughing becomes possible. Burning on the one hand and waiting on the other might be avoided by running gangs of specially designed notched cutting discs in front of the plough. The flat notched discs might be preceded by small rollers or spring tines to press down the material so that they could rotate in the plane of the direction of movement of the whole machine. The action would be to cut the trash into pieces which would be to


a great extent turned under by the plough. A disc harrow behind the plough would break up the clods and leave the land in a suitable condition for early planting. It seems possible that this method could be used in deep loamy soils when in suitable condition, where subsoiling is not necessary.

Working in Trash After a plant or ratoon crop has been reaped, the trash makes it

impossible to do any work on the soil unless special means are used (Figs. 37, 39, 40, 41). The old system, still widely practised, involves the removal of the material from the cane rows by hand and piling it in alternate rows so that the cane lines are exposed and work can be done between rows from which the trash has been removed. The trash may be cut through mechanically and work done along the line of the cut. There is no apparent reason why the former method should prove difficult to carry out by a machine using modifications of implements employed for hay-making. A device for the second method consists of a 24-in. notched cutting disc in front of a subsoil standard with a removable chisel point behind which the fertilizer is dropped in regulated quantities from a hopper feed (Fig. 38). The furrow is cut by the side of the line of roots which may have to be located and indicated by markers. Two can be cut at the same time with a machine providing for adjustment of the distance between the standards to suit cane row spacing as illustrated in Fig. 38. The method gives light surface cultivation along the lines of the furrows up to a depth of 8 in., places fertilizers in correct dosage below the trash, and disturbs the trash very little so that its effect in keeping down weed growth is not impaired. The trash could easily be parted on each side of the cut by the same machine leaving an open furrow for irrigation.

Mechanical Planting The planting pieces or setts used for hand and mechanical

methods of cane planting are usually prepared manually from whole canes. In many places, the cut ends are dipped in a fungicide or otherwise specially treated, again by hand. The setts ready for planting are loaded into the bins of the planting machine, and put by hand into the shoot down which they drop to the furrow. Thus there is often much manual work included in so-called mechanical


cane planting, so that the term mechanically assisted planting would better describe present practice (Fig. 44).

Whether a different method of preparing seed pieces and a modification of the planting process are possible is worthy of investigation. At present the setts consist of a number of joints ranging from two or three, to five or more in each piece, while sometimes the whole cane is used, being dropped into the furrow in one piece. It is known that smaller portions of the cane, consisting of the joint or node, with the eye, root band and a small part of the internode on each side will germinate and grow in most circumstances just as satisfactorily as the large seed pieces. This suggests that these " nodal setts " could be used with advantage if they could be handled without damage. The procedure might be to prepare the " seed " material at a central place in the following manner. Whole cane selected for seed would be cut into nodal setts by machines using either revolving or guillotine knives. Operators would separate the internodal pieces, and the nodal seed portions would be moved on a travelling belt to a fungicidal bath, being inspected and culled in the course of this transference. From this bath they would pass along another perforated belt to drain surplus liquid, and then be surrounded individually with moist clay in such a manner as to form a rough sphere with the seed piece inside. These could be surface dried in warm air and wrapped in some suitable covering in which could also be put a small portion of the type of fertilizer used in the soil in which the cane was to be planted. Planting material of this description could be sown mechanically at correct spacings by a machine designed for the purpose, which would also apply the balance of the fertilizer and give the first weed control spraying.

So far as is known this method, here suggested for investigation, has not been tried though nodal setts prepared and planted by hand have been found to germinate and develop normally. Several variations appear possible, such as the omission of the wrapping and its contained manure. The cut setts after fungicidal treatment, could be dipped in a cream of clay and water several times, being air-dried between successive immersions. Different mixtures for the coating of the pieces might be tried. The effect of a clay coating would be to prevent rapid drying of the seed piece, thus preventing deterioration and assisting germination.


An alternative procedure would be to cut and treat the nodal setts, and wrap them mechanically in tough paper which would soften when wet and be easily penetrated by the growing shoots. By using appropriate lengths of twisted continuous band, the result would be a number of nodal seed pieces strung together at the predetermined planting distance. The fertilizer required would be wrapped in a portion of the paper between the setts so as not to be in actual contact with them. The clay dipping and partial drying might still be advisable. The planting machine, consisting of a sturdy furrow opener with a feed pipe behind it curved to the rear at the bottom, would carry the coils of seed band on drums and feed continuously behind the furrower. The device for covering in and rolling would be similar to that now used.

Objections to this apparently complex series of operations are possibly greater overall cost of planting, though this remains to be investigated with other details ; and the expense and trouble of establishing and operating a special seed-piece preparation unit. Advantages would be the more careful selection of seed ; greater ease and simplicity of the actual planting operation ; less loss of seed per ton of cane cut for the purpose; and availability of a considerable proportion of internodal parts of the cane for other purposes, particularly for feeding to animals. The careful control and supervision possible would reduce damage to seed pieces, and the effects of rough handling of naked setts in the field would be entirely avoided. Seed preparation would be centralized and the distribution of new varieties greatly facilitated. By any method developed from those suggested, a planting machine operated by 2 men (in place of 4 or more with existing models) would be able to carry seed for at least an acre at each loading.

Mechanical Reaping The mechanization of reaping, like that of planting seems to

have developed from attempts to imitate the manual worker rather than to achieve an effect by applying entirely new ideas. Mechanical planting as now understood is putting into the soil the same sort of seed pieces as are dibbled in or laid into a furrow by the manual planter, preparing and carrying those setts in exactly the same manner as before, with the possible exception of special additional treatment.


Mechanized cane reaping has with minor exceptions followed the pattern of devising a machine which under the conditions in which it is intended to work, will cut the cane, remove the top and take off the leaves (trash), loading or leaving each cane in one piece. There seems no reason why the cutting of the cane at the base should not be followed by chopping it up by the same machine, tops, leaves and all, into pieces a foot or so long, separating the unwanted material by air blast either in the field or immediately on arrival at the factory. An objection to this proposal is to be expected from the factory people that rapid deterioration would set in and sugar recovery be prejudiced. The extent of this, if any, would depend on the time interval between cutting and the arrival of the cane at the first point of treatment at the factory. With quick delivery there should be no " commercial " deterioration, that is the effect should be negligible from the point of view of factory recovery. Such a method would be useless if the cane were to be delayed after cutting and before reaching the factory process.

Weight per cubic foot of cane in trailers and rail cars would be greater than it is now. Mechanical handling would have to be adapted to the new form of the material, from field carts to factory carrier.

A system suggested by A. Maclean involves the mechanical cutting of the cane into short lengths in two operations, separation of trash by winnowing, and a suitable form of quick transport to the mill. The first cutting operation would sever the cane a foot or so above ground level, at the same time dividing it into short portions by rotating cutters on a vertical shaft, which would be carried into the machine by fingers working between the cutters. Additional cutters are proposed for tangled and recumbent cane not severed otherwise. The stubble would be cut by an adjustable angled rotary knife, with a device for collecting and elevating the short lengths, mounted at the rear. The cane, separated from trash and tops by air blast or in some other manner might be discharged into a large wire mesh basket suited to the handling and transport system used. The waste left on the field would be in a form which would make it easier to perform subsequent field operations.

The methods of mechanical harvesting used in Hawaii are

MECHANIZATION OF SUGAR-CANE AGRICULTURE 20,1

damaging to the land, large quantities of soil and cane roots being removed, and separated from the cane at the factories. The problem of soil conservation is present in acute form for these reasons. Attention is being devoted to new methods which will correct the situation.

Electric Power The application of electric power to sugar-cane agriculture

remains to be considered. Where cheap electric power is readily available and can be conveniently distributed to points where it can be tapped, there are numerous farm uses to which it can be put. Such conditions prevail on an irrigated plantation using water pumped by electricity from underground sources. In these circumstances high tension transmission lines are used to supply power to the pumps, a transformer being employed for each pump motor. In this way there are take-off places where low tension alternating current can be supplied for other purposes, provided that transformers of adequate capacity are installed. With such a transmission system already constructed for a primary essential service, minor feeders and transformers can be connected with it to extend the use of electric power. These considerations apply more particularly to larger plantations, but small farms can make use of electric power with advantage if connection to a supply can be made easily.

Weedicides are sprayed on the land both by portable and power machines. The modern portable sprayer is a strong metal cylinder capable of containing air under pressure and a corresponding quantity of liquid. After discharge by the operator, the sprayers are taken to the side of the field and recharged with air and spray liquid. The air compressors used could be electrically driven.

Minor repairs of field equipment could be assisted by small electric tools of various descriptions. Lights in the field roadways at convenient points are often needed, more especially during the harvest period when there is some night work and greater risk of fire. The method of checking the flowering of cane by overhead lights for short periods during hours of darkness is likely to bring about extended use of electricity in the cane fields for this and other purposes.

Electric power may be used to deliver water under pressure for


overhead irrigation to permanent or portable systems. It would appear worth while to consider putting in a pressure mains supply to the fields using asbestos cement pipes. One or more electrically powered central pumping plants would then provide all water for this form of irrigation. Surface minor canals and ditches within the area would be replaced by pipes. Evaporation, seepage and percolation losses would not occur. Transportable pumps would not be needed, and pumping costs would be lower. The expensive maintenance of open canals and ditches would be avoided, and water would be available under pressure for fire control. A distribution scheme of this nature could be used with portable field application units. The design and layout would necessarily have to provide and maintain the correct pressure at the sprinkler heads. Cane hoists for transferring loads from field carts or cars to a main railway system are conveniently powered by electric motor when this is possible, as also are electric winches for shunting rail cars at loading sidings.

The application of electric power to cultural work on the land is more speculative, though the future may bring about outstanding developments in favourably situated places. The major field operations of ploughing and subsoiling could be performed by electrically powered cable units in flat fields, as also could planting by machine under similar conditions. An extensive system of overhead feeder and return lines would be needed, which could supply power for cane transport during harvest. Implements now in use would have to be redesigned and changes made in plantation layout. Should any extension of the use of electricity in these directions take place, it would most likely commence on cane plantations where an internal transmission system already exists for other purposes. The possibilities also seem remote for the use of individually motored tractive units connected by armoured cable to power outlets at points near the fields.

General Considerations : Servicing, Maintenance and Repairs

The overall extent to which sugar-cane agriculture can be mechanized in a particular case is determined by the local conditions, which also influence the selection of power units, implements and methods. The integration of manual labour and the


use of animals with mechanically performed operations is often important. The constant aim is the economic production of sugar, consistent with the conservation of the soil, and these factors must be related to the description and cost of the equipment required. The choice of tractors should be such that the machines can be used for a variety of work, or in other words, kept fully employed. At the same time a reserve of tractor power should if possible be available. Strict adherence to makers' directions in regard to servicing and maintenance is essential. Regular overhauls and repairs are necessary. Spare parts required from time to time should be secured in advance so that when the overhaul is undertaken they can be installed without delay. "Where the extent of farm operations justifies a well-equipped workshop, all such work will be executed there, but full use should be made of the advisory services and repair facilities offered by most manufacturers and furnished by their representatives. A point to remember is that they, like the owner and user, are interested in making sure that the machines are maintained in efficient working order.

Tractors All power machines should be carefully examined, overhauled

and repaired where necessary immediately they have completed their seasonal work, so that when needed for the next job they are in reliable operating order. When fleets are of adequate size, each machine should go into the workshop at stated intervals for checking over, and for such repairs as are indicated by examination whether it appears necessary or not from the field operator's viewpoint. These matters have to be related to working requirements in the field, and close co-operation of staff in both is necessary.

Implements Similar considerations apply to implements, which also require

regular field servicing and seasonal overhaul. The power unit and the implement are strictly complementary. One is useless without the other, and similar degrees of care and attention are essential for both if they are to render good service. When implements have to be moved from one part of an area to another, particularly if metalled roads have to be traversed, they should be transported by truck or other suitable vehicle unless they are fitted with


rubber-tyred land transport wheels. Few implements are designed for idling movement in excess of that involved in performing the work on the land for which they are designed and even when land wheels are provided the shocks resulting from travel over hard ground may cause damage. In this respect an agricultural machine should be regarded like a racehorse—to be used to the best advantage in the sphere of work for which it is designed, and to be moved with great care to and from the places where that work is done. The same remarks apply to track-type tractors.

Apart from mechanized maintenance is the often neglected general care of implements, particularly when they are laid by for inoperative periods. Their efficient working depends very largely upon attention to greasing and oiling of all moving parts, to the cleaning and protection of working surfaces, and proper adjustments of settings. Bolts tend to work loose and should be regularly examined and tightened or replaced. Plough shares and discs need to be kept clean and sharp. At the end of the season's work, implements should be immediately overhauled and prepared for the next period of work. After being repaired, main frames," carriages, wheels and axles should be painted, and all parts coming into contact with the soil under working conditions coated with rust preventative. Weatherproof accommodation for off season storage is important. Land-tyred wheels, complete with the tyres, are removed, examined and repaired where necessary, and stored in a cool dark place after the tyres have been coated with a special tyre paint.

Field Servicing Large undertakings use service vehicles which convey

mechanics, materials and portable tools through the areas where machines are working, to make regular inspections of equipment, effect minor repairs and carry out field servicing. A similar arrangement for rubber-tyred tractors and vehicles is necessary if considerable numbers are in use. A competent man with a light motor vehicle carrying a tyre pressure gauge, tyre inflator worked by the engine, and other tools, should examine every tyre in use as frequently as possible. His work is to check and adjust tyre pressures, examine wheel alignments, correct faulty working where he can, look for damaged and worn tyres and bearings, ordering

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repairs or replacements as may be required, and generally to act as vehicle examiner and service man. With extensive plantations where numbers of tractors are working in various locations on different tasks, fuel and oil should be carried in suitable tank vehicles for supply to the machines at points as near as possible to their working places. This does not always apply to haulage tractors which convey cane to a railway or factory. In such cases it may be more convenient to have a fuel and oil station at or near the load discharge point. Unless very special care is taken the fuelling of machines by using drums in the field is wasteful and expensive. Any manual pouring of fuel oil should be avoided. Transference from container to tractor tank should be by pump with measurement of all quantities used.

The extent to which these methods are applicable to smaller areas depends upon the numbers and variety of equipment in use. The three separate units described can be combined, or centralized, as circumstances require. The important thing is so to organize inspection, servicing and field supplies, as to keep equipment working with the minimum of lost or idle times, and to detect and correct faults before they develop into stoppages and breakdowns.

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CHAPTER 15

MANAGEMENT, SUPERVISION AND STAFF

Basic Principles The success of any undertaking is mainly dependent upon a

defined policy which is given effect by careful direction and control of all operations connected with and related to it. Sugarcane agriculture is a continuing venture which may by modern standards be regarded as permanent. Indeed as has been shown, the crop has been grown in some lands without intermission, other than crop cycles associated with good planting practice, for 300 years. Some credit for this must be given to good methods of management. Though agricultural methods over this long period have undergone remarkable changes the basic principles of control are little altered. They include careful planning, the employment of capable and efficient staff and operatives and unremitting attention to all phases of the enterprise.

Operational Planning Operational planning, a corollary of farm and field planning, is

a primary requirement of good management. It includes all matters of land management and crop production. Equipment and materials of all kinds, personnel, and methods are the subjects which fall within the purview of management and supervising staff. These affairs are considered and determined within the policy which has previously been decided. The over-riding decisions which embody policy made by a board of directors or other supreme authority are interpreted and put into effect by the plantation manager, who must determine and approve how best to proceed. Staff consultations are conducted, proposals discussed, and conclusions reached which form the foundation of the operational plan. The general outline is given to the staff, each of whom works out the details which concern his particular sphere. Upon being satisfied that the completed proposals are in every way

296

MANAGEMENT, SUPERVISION AND STAFF 297

sound, and that they fulfil the requirements of the approved general programme, the manager signifies approval, and work proceeds.

M a n a g e r i a l Q u a l i t i e s

Managerial responsibility calls for much more than ability to plan, organize and administer. Wide acquaintance with general agricultural practice and specialized knowledge of sugar-cane production must be combined with competence to consider, discuss and criticize civil and mechanical engineering matters, as well as numerous other activities, which are essential to efficient crop production. Professional and technical ability should be combined with vision, determination, forbearance and sympathetic understanding of others. Indeed the personal human attributes are just as necessary to successful management as are the material ones associated with the actual conduct of the work of a sugar-cane plantation. The manager should command the complete confidence of his staff and of the work people, being at all times regarded with respect as an authority on the work under his control ; and as a person who may be consulted on points of detail, whose advice may also be sought on subjects of purely personal interest and difficulty. The quality of a manager is very quickly assessed and judged by the staff and employees. Failure to merit their esteem and regard will adversely affect the successful conduct of the business.

Staff The choice of staff is guided by similar considerations. The

responsibility for execution of the detailed work devolves upon them. They provide the controlling linkage between the management on the one hand, and the work people on the other. Not only should each of them know how every part of the work under his control should be done, but he should be able to perform it himself so as to demonstrate correct methods and check errors. The numbers of staff and their individual qualifications will depend upon the extent and variety of operations conducted. The requirements of large irrigated plantations using highly mechanized methods for agricultural operations will display remarkable differences from those with a similar output under conditions of


natural rainfall; and though smaller areas using those systems may need fewer men in staff positions, the same kind of services will be wanted, so that greater versatility on the part of each man is called for. One of the duties of a manager is to provide adequate qualified staff for all services, and to make certain that each of them is fully employed.

Plantation Organization—An Example It will be helpful to consider the staffing of an irrigated estate,

say 30,000 acres in extent, of which 16,000 acres are devoted to sugar-cane production, the remainder consisting of stony woodland, swamp, pastures and bush, some of which may later be put into cane. It is assumed that all possible operations are mechanized, with the exception of cane reaping and loading. The average cropping cycle is plant and two ratoon crops, involving replanting one quarter of the total cane area each year. A factory is situated on the area and is the focal point of the cane plantation. It is not included in the staff organization discussed here. Water for irrigation is obtained by electrical pumping, there being one large supply and a number of tube wells of varying output. The total volume of water pumped is 170 cusecs (27,500 million gal. per annum in 300 days). Electric power is not generated by the plantation. There are 40 miles of 2 ft. 6 in. gauge railway track with 15 sidings and hoists.

The activities of such a unit fall into four categories :—Agricultural production, and three branches of engineering— mechanical, electrical and civil, each being in charge of a senior man, responsible for the conduct of all work within his domain. It is essential that the four divisions work in consultation and cooperation with each other, and with the administration division as represented by the Chief Accountant and his staff. If this important feature is neglected, confusion occurs, accompanied by strained personal relationships and adverse effects upon general efficiency. The senior men are provided with assistants, of whom more are needed in the agricultural division than in the others. The Health and Welfare division also depends for success upon the maintenance of cordial relations throughout the organization. The medical officer and his staff can do much to promote goodwill and to smooth out difficulties arising from the clash of


the senior officer and his principal assistants. They should possess a practical outlook, combined with a deep knowledge of agricultural science, and the special personal attributes which earn the respect and co-operation of other plantation staff. The position of a scientist on a sugar plantation is not an easy one to hold. However brilliant a man may be, inability to command the confidence of the operational staff will retard the introduction of improvements, if indeed it does not prevent them. When the agricultural staff themselves have been scientifically trained these conditions may not arise, but the so-called practical man who is carrying out field work can be most ingenious in his methods of demonstrating that new ideas will not work, unless he has developed a personal esteem for the research man, and an admiration for his work. Having achieved this regard, the research division will rapidly succeed in securing the collaboration of all other staff and the application to field practice of the results of investigations.

Cultivation Division and Staff The agricultural, or cultivation division is the largest in numbers

as well as in extent and variety of activities. Although their main occupation is the work on the fields, the staff must be sufficiently versatile to conduct all operations related to the plantation in respect of roads, drains, minor irrigation works, transport, control of labour, field records and farm accounts. The other professional staff will be concerned with major works and their execution, though quite often the supervision of labour engaged on them may fall upon members of the cultivation division. The management and accountancy organization determine the form in which records are to be kept. The planting policy will be decided at a high level, as will other matters concerning crop production, the executive work devolving upon the field staff. The personnel of this division are the core of the whole structure. They are in the closest contact with work people, with the land and with the crop. Their mistakes are reflected in results and their standard of efficiency determines very largely the financial return of the undertaking. Their duties require physical strength and mental stature of a high order. The physical strength is needed to endure the exacting conditions of supervising work in the field ; the mental stature includes know-

MANAGEMENT, SUPERVISION AND STAFF 3OI

ledge of agricultural methods and a devotion to work on the land, amounting to a love of nature in its varied manifestations as they appear in the cane fields. Abilities of this kind are innate. Without a natural attraction to the land, the knowledge acquired by training, study and experience will not develop the attributes of a first-class sugar-cane field man, although these qualifications are essential to success.

Apart from ability as a farmer, members of field staff should be capable of carrying out elementary survey work including levelling, which is of special importance in connection with internal field lay-out for drains, irrigation furrows, and planting. Other related matters are line and area measurements, compass bearings, methods of laying out right angles, measurement of water and simple survey computations. Among the primary duties are the systematic planning and supervision of all work in the field, and the general control of the labour engaged upon it. The care of livestock where farm animals are used, and the operation of farm machinery and implements largely devolve on the agricultural staff.

Engineering Divisions Each of the three engineering divisions should have a specialist

in charge. The mechanical and electrical engineers require workshops, and the civil engineer a drawing office, which can serve the occasional needs of other departments. The responsibilities of these branches are indicated in the diagram. The secondary staff would include provision for the workshops, field survey, buildings, roads and bridges, railway and irrigation works, the numbers and their duties depending on the extent of the services required.

Materials Store There should be a well-organized materials store serving all the

operational departments. The stocks carried would vary with the availability of supplies from local business houses, and their cost. A materials store carrying all requirements is an expensive undertaking, only necessary when supply centres are remote and deliveries of requisitions are delayed for long periods. The extent and nature of stocks carried should therefore be carefully regulated in regard to estimated needs and the time taken to fulfil orders on suppliers.


The over-riding consideration is the ordered progress of all work related to the crop itself, for which necessities should receive priority of attention. Known essentials should be foreseen and ordered well in advance so that prompt issue of them can be made immediately they are wanted. The organization and conduct of the stores are highly important in the whole plantation system. They demand methodical care throughout, so that records show accurately the stock of any item, the consumption during previous periods and the cost; the position regarding orders placed and expected deliveries; the issues made, with dates and quantities. Stores represent money in material form, and must be properly controlled and accounted for, as they form a major item in crop costing.

The Accountant and His Responsibilities The divisions discussed so far are concerned with crop pro

duction and varied activities directly related to it. In order to exercise his authority in regard to operational control, the manager has an office staff of whom the principal officer is the Accountant. A large undertaking would employ a person of professional standing who is responsible for the organization of the office, its staff, records, and general working, particularly that related to finance and accounts. The accountant should also be in charge of stores records, in order to ensure that the stores control system is fully effective. This duty would not interfere with the purchase and issue of essential materials except in regard to procedure and accounts. Special attention should be given to the arrangements for paying work people. They should be such that the delay between completion of working periods and payments in respect of them is reduced to a minimum consistent with accuracy, while the actual amounts due to each worker should be handed to him with as little waiting as possible at the place of payment. Disputes regarding correctness of pay and tardiness in paying for work done are fruitful causes of labour unrest, which easily lead to interruption of operations, and even to more serious consequences.

It is not proposed to deal in any detail with the organization and duties of the accountant and the office, but there are certain matters of practical interest which may be usefully mentioned. In many places, sugar-cane plantations are at such a distance


from business centres, that special arrangements are necessary to provide members of the staff and their families with day to day necessities, including money. Various ways of meeting these requirements are adopted, in which the accounting branch often plays a dominant part, as indeed it must in all matters of estate finance. It is desirable that the more senior grades of employee, whose salaries are paid into their banking accounts should be permitted to draw their current cash requirements from the cashier. This is conveniently done by the encashment of cheques, limited in amount and frequency under staff regulations. On rare occasions it may be found that abuse of such arrangements may occur, but this can usually be prevented by surprise checks on cash, and insistence on strict observance of rules. It is desirable that the manager should exercise his authority when emergencies arise occasioning the need for drawing more than amounts provided by regulation, though any such sums should be less than the total emoluments for the member of the staff concerned for the particular period. Experience of misuse of cheques and absence of adequate accountancy control over the cashier have demonstrated the importance of this apparently minor aspect of management.

Financial Control Through the work of the accountant's office, the manager must

at all times be in a position to check and control expenditure, and to ascertain the cost of any item of work, whatever its nature. Financial control must reach to every part of the plantation and to every kind of operation. It is best exercised through a budget system under which annual estimates of the cost of all activities are prepared, discussed, amended and approved before the beginning of the period to which they relate. Information on which the budget is compiled is supplied by all divisions. The statement in its final form provides a picture in figures of the proposed working of the plantation with supplementary details showing the nature, extent and cost of each part, reduced to a summary of crop data and estimated cost. It furnishes a guide to the cash requirements at specified intervals, estimated receipts, and material supplies. Expenditure required for capital works including replacements of major items of equipment is shown in separate estimates, which


are usually subject to the approval of the directors or some other authority senior to the manager.

An annual budget of recurrent expenditure will need revision as the year passes, brought about by unforeseen and uncontrollable factors which inevitably arise with any plantation project. Constant scrutiny of accounts is necessary, and periodical comparative statements showing actual amounts spent against estimated disbursements, enable the manager to exercise financial supervision, and to decide upon the various changes which are required in the original estimates. Strict control of amendments of this nature is desirable and none should be permitted without authority. Operative staff sometimes find such careful regulation of expenditure irksome. They feel that certain work must be done, and that they should be the best judges of its necessity. However, on a large plantation it is essential to work as nearly as possible to a prearranged programme, with defined responsibilities for each grade of staff, under supreme general control. Only in grave emergency should unauthorized departures from it be permitted.

Qualities Required in Staff The conditions under which members of the staff of a sugar

plantation live and work require character, temperament, and ability of a special nature. They live in restricted communities formed of themselves and their families, often remote from large centres of population. Working and social activities bring the same people together almost constantly. Duties are exacting, and difficult to get away from during leisure hours. Tempers may easily become frayed; petty worries assume alarming proportions ; and unhappy relationships develop when people of opposing temperaments are brought into constant contact. Man is supposedly gregarious, but only under congenial circumstances of living and companionship will he display this human characteristic at its best. Great advances have been made in providing comfortable homes and pleasant amenities for all grades of staff on sugar plantations. Many of the antagonisms which developed under former conditions now rarely appear, but there still remains the need for careful selection of staff, with regard to personal attributes as well as ability. Among the important qualities are tolerance, good temper, and an attraction to the land. These apply


as much to office staff as they do to those who are engaged in the varied aspects of crop production. Physical fitness is essential and experience has demonstrated the wisdom of requiring prospective employees for all grades of staff posts to undergo a searching medical examination, which should be comparable with that required by an insurance company for a first-class life.

Medical and Health Services Large organizations maintain their own medical and health

division, which should provide for regular examination of members of the staff, and for the normal requirements of cases of illness amongst them and their families. The plantation health and sanitation services come under the general supervision of the medical officer, who in these matters acts in the capacity of adviser to the management, the necessary work being preferably conducted by plantation staff in accordance with approved instructions.

Staff Regulations Except for small plantations with very few staff grade employees,

it is desirable to compile regulations and instructions for the personal guidance of all members of the staff, including such variations as are required for different grades, some of which may be issued solely to persons in particular grades. Compliance with rules and instructions should be a condition of employment. They supplement the particular terms of engagement set out in the letter of appointment, or contractual agreement of every staff employee at the time of entering the service of the organization. Amendments and additions become necessary from time to time and may be issued in the form of slips to be pasted on to interleaved blank sheets in the original booklet of regulations given to each person.

The Selection and Training of Staff While the methods of selection and training of junior staff may

be said to be similar to those used with success in other industries, there are points of particular interest. It has been shown that the work of the agricultural branch is of leading importance, and unless the men engaged in the activities of that division are of a high standard of character and ability, the plantation will not be successful. Senior field staff should have had academic as well as


practical training, and should hold qualifications of a recognized educational institution. In general, it is preferable that they should gain experience of work on a plantation before proceeding to their higher institutional education. Though this principle applies to most industrial activities, its value has been recognized by experience of the cane sugar industry. Close co-operation between the industry, the schools, and agricultural colleges and similar higher educational establishments is necessary. A procedure which has been successful is to arrange with the headmasters of secondary or high schools for groups of boys of school-leaving age to undergo vacation training under the working conditions of a sugar plantation. A convenient number for each course is 12. The boys should have reached university entrance standard, and should be selected with regard to their apparent desire to adopt agriculture as a career. It is an advantage if arrangements can be made for them to live together in a hostel or similar establishment, under the general control of one of their masters, preferably on the plantation. The course of instruction, which should extend over 6 to 8 weeks should be planned in advance, and should include work, instruction and observation in the field with members of the agricultural staff, and lectures. The field training is most effective if the boys work in pairs, each pair being in charge of a member of the agricultural staff responsible for a particular part of the normal practice on the plantation. The pairs move from one such " tutor " to another in accordance with a pre-arranged scheme, so that all the boys gain some experience of every phase of the work which is receiving attention on the plantation at the time. The lectures are given by various members of the staff, and others, on subjects related to the field work done and to the industry generally. Each student keeps a notebook in which he records notes taken in the field, and at the lectures. At the conclusion of the course a written and oral examination takes place. All staff and lecturers taking part are required to record their opinion in respect of the traits displayed, the general conduct, and work accomplished by each student, which is considered with the results of the examination and the notebook. An assessment is thus made of his suitability generally, or for any special branch of plantation work.

The next step is to select some of the youths for temporary appointment to junior staff posts, conveniently termed " student


apprentices." Those who accept such an offer come tinder the same control and discipline as other junior staff grades, but are regarded as being in training. This stage is of particular importance in a successful staff recruitment scheme. It is desirable that junior employees of this type should be given every opportunity of showing their aptitude for various branches of plantation working. They should live under conditions which ensure good meals at regular hours, and be provided with facilities for study and instruction. If possible a hostel under capable management should be used. This aspect of initial training is of equivalent importance to the duties, study and instruction. The early formative period of plantation experience exercises a profound effect upon the future outlook and usefulness of young men, and something closely akin to home influence is necessary. Recreation and interesting occupation should be encouraged during periods of leisure, and compliance with rules of general conduct should be required. The phase of student apprenticeship should extend over at least one year, which will generally be found sufficient to determine the suitability of each individual for permanent employment when he becomes qualified, and the branch of work for which he displays special aptitude. At the same time the youths themselves will have gained sufficient experience to enable them to decide for or against a plantation career.

Higher Training The institutional training which follows should be such as to

give general instruction in agricultural science, providing for specialization in one or more subjects which are decided in regard to the desire of the student on the one hand and their practical utility in connection with plantation operations on the other. Students should be encouraged to return to their employers during part of their vacations, or to go to other plantations, in order to provide themselves with further practical experience, and if necessary, earn money to be devoted to defraying a part of their college fees. The extent, if any, to which employers provide the cost of such higher training does and will vary considerably. In many cases scholarships are awarded by Governments, public authorities, and employers, with conditions which may include an undertaking to accept engagement at not less than a stated salary


for a definite time after successful completion of the course of study.

The great advantage of practical experience under the normal working conditions of an industry between leaving school and undergoing higher training have been amply demonstrated. It has been found that the student apprenticeship period enables young men to secure greater advantage from their subsequent academic studies than would be possible by proceeding directly from school to college. The practical outlook becomes well developed, and in the cane sugar industry the application of scientific principles to farm operations follows naturally.

Staff Friction—The Old v. The New The method of appointing and training junior staff varies con

siderably in the different sugar producing countries. It is only in recent years that the importance of the scientific approach to practical farm work has been recognized, and the necessity for it is not yet fully appreciated. Many of the " practical men " whose whole experience has been in cane as they say, and who have attained high executive authority still remain unconvinced of the importance of institutional as well as practical training. They often point to failures to justify their views, not realizing that in most cases they have arisen from faults of selection on the part of the employer, lack of experience of farm conditions and work, and other essentials, which must supplement academic education. Passive resistance developing in some instances to active hostility is occasionally displayed by staff, who have had no training apart from practical experience, to the system described, and to those who have been appointed after successfully passing through such courses as combine practice with scientific instruction and achievement. This attitude creates difficulties for all concerned, particularly the management, and the young men against whom it is directed. It can be countered to some extent by an educational campaign to assist those who have not enjoyed the more advanced opportunities available under modern conditions. If that fails, the remedy is a programme of gradual but certain replacement of the die-hard element. The increasing need for efficiency in all phases of agricultural production demands the services of highly trained staff in all grades. Opportunities for those who are not so


qualified and who do not display the personal and mental characteristics essential for success in their work, are becoming less, and will in time almost disappear with the changing practices of sugar-cane production.

Smaller estates and plantations have staff requirements differing in extent, and variety, though equivalent qualifications and experience are necessary. In many cases men have to be more versatile. Specialist staff is not required constantly and is called in when needed. Methods of management and control should be similar in nature to those used for larger undertakings.

The Colleges and Their Policy

The ideal combination of practical ability and the application of science to the every-day work of a sugar-cane plantation is not easy to achieve. Apart from the basic considerations of temperament, character, and attraction to an agricultural career on the part of the student, the curriculum of the college, as well as its policy, and the quality of its staff are of great importance. Unless the whole plan of institutional training is such as to inspire as well as educate, bringing out the best attributes of students, and affording opportunity for the display of individual personality and choice within the broad scheme of training provided, it will fail in its object. There must be the closest association between the college and the industry. The staff must at all times be fully aware of progress and trends in the various spheres of agricultural production, commanding the respect and confidence of those actually engaged in that work. At the same time research should form an important part of the college work, with the main object of studying field problems of practical utility. Though fundamental research may also be conducted, the extent to which agricultural students intending to take up a plantation career participate in such investigations should be carefully regulated. Individual interest, and the ultimate object of the course of instruction are taken into account, but it must not be forgotten that the latter will determine the success of the training, reflected as it should be in later results in plantation management and production. These observations apply with minor variations to all phases of agriculture, but the present purpose is to stress their importance to the future progress of the cane sugar industry.

CHAPTER 16

FARM AND FIELD RECORDS

The Value of Field Records The business of efficient plantation management includes the

compilation in a systematic manner of all data relating to the individual fields to provide basic information for the interpretation of crop results ; the determination of costs, and financial returns ; and the variations in productivity from crop to crop. The detailed records from which such summarized statements are abstracted include those of the accounting division and the farms, the result being a compact return in respect of each field.

Survey Plans The first requirement is a detailed survey plan depicting the

plantation as a whole with all permanent features including field subdivisions and their areas. This master plan should be supplemented by sectional plans on a larger scale, of which more than one copy may be required for each in order to show in a convenient manner permanent and temporary or variable data. The former include areas, soil types, contours and physical features, while the latter refer to variety of cane, dates of planting and reaping, stage of crop cycle, and similar matters. An accurate knowledge of areas is the foundation of all field records, as well as of normal farm operations.

It will be helpful to state briefly the relative merits, and mode of using plans and maps obtained from surface and aerial surveys. These matters are more fully discussed in Chapter 8. Ground or surface survey work is expensive, and difficult to carry out in areas of standing cane. Though boundary surveys will in almost all cases be available and need not be repeated, supplementary work may be necessary to demarcate and determine the areas of fields. Aerial photographic surveys are low in cost and of a standard of accuracy amply sufficient for all plantation purposes. A great advantage is that they include all permanent and temporary features, visible from the air at the time of survey. When

310

FARM AND FIELD RECORDS 311 the final photo-plan has been compiled, the areas of fields can be determined by a planimeter and this information supplied to the planter with other mensuration data.

The Field Ledger Field records are conveniently kept in the form of a ledger with

separate sheets for each field of adequate size to provide space for entries for several years. The head of each sheet bears the name of the plantation, the name or designation and location of the field, and essential data regarding permanent features, prominence being given to the total, and the net or plantable area.

Information to be Recorded Special characteristics such as the presence of exposed rock,

groups of trees, roads and tracks, and the areas occupied by them are noted. The nature of the soil and subsoil is briefly recorded with the type of drainage. These, with any other matters of importance, are followed by crop data, which include the variety of cane, the stage of crop cycle or class of cane, i.e., whether plants, or 1st, 2nd, etc., ratoons, and the main operations carried out on the land and the crop in order of performance, described as far as possible in printed sub-heads, with sufficient space for inserting important details, with dates and costs. Provision in the sheet should be made for reference to special operations and to unusual occurrences affecting the work in the field, or the cane. When the crop is reaped the yield of cane and of sucrose (obtained from mill returns) are included, the field figures for yield per acre, and cost per acre and per ton being ascertained. These cost figures will obviously apply to field operations only, and will differ from final all-in costs. The age of the cane at reaping and production data, such as sucrose per month, may readily be derived from the record.

A specimen field ledger sheet is shown. The form used and information recorded can be varied and simplified to meet the needs of those who find the system helpful, but the value of the method as a help in management and control should be the main consideration. The minimum of useful data would be :—

(i) Name, location and net area of field. (ii) Variety and class of cane,

x


(iii) Date of planting. (iv) Date of reaping and age of cane (from planting or last

reaping), (v) Total tons of cane and of sucrose,

(vi) Tons of cane and of sucrose per acre.

All entries must be kept up to date so that after the close of any period a picture of the work done in each field, and its cost, when such data is recorded, can readily be ascertained. Various methods are used to collect the items of information required. The best sources for most of them are the field pocket books kept by the farm operational staff, abstracted in a manner suited to the form of field ledger used and supplemented by figures from the plantation accounts.

Advantages of the Field Ledger System The utility of the field ledger increases with time. Apart from

the immediate advantages which will be apparent from the description of the system, a historical record of each field is provided. Variations in yield from crop to crop, and field to field are indicated ; failing fertility is disclosed for which appropriate corrective measures can be promptly taken ; a helpful competitive spirit amongst farm staff is introduced, and assistance given towards more efficient and profitable field husbandry. Readily available data for annual crop surveys is provided, which may be compiled for the plantation, and for all units engaged in cane production within the territory concerned. Under modern conditions these compilations have become essential to the welfare of sugar-cane planters and to the industry as a whole.

Annual Crop Surveys The detailed information recorded for individual fields by the

field ledger system or other convenient method should be compiled in a summarized form for the plantation as a whole. The resulting statement is an abstract of production and cost data,' which should be prepared in the same manner each year and carefully studied by operational and managerial staff. Considerable variations in the form of such compilations occur, brought about by different field practice, production with or without irrigation,


and varied systems of management. The example quoted below is in respect of a plantation made up of five main divisions each being further subdivided into farms. The areas of cane reaped annually in respect of single farms range from 325 to 600 acres, with an average of about 450 acres for the 16 farms. A return is compiled for each farm from the field records, the same form being used for all. The completed summary includes data for each farm, for the groups of farms forming wach division, and for the whole five divisions which comprise the plantation.

The production information is shown in five main sections :—

(i) Area reaped, (ii) Tons cane reaped,

(iii) Tons cane per acre. (iv) Cane/Sugar ratio. (Tons cane per ton 960 sugar.) (v) Tons sugar per acre.

The figures for the last two are derived from data supplied by the mill. In each of the five sections separate figures are given for:—

(a) Fall plants. (b) Spring plants. (c) 1st ratoons. (d) 2nd ratoons. (e) 3rd and older ratoons including standover cane.

Area reaped is recorded in acres, and percentage of the total. Totals are entered for areas, and averages for all other figures in respect of each farm, division, and for the whole plantation. The statement should be compiled immediately harvesting has been completed, from data recorded in the ordinary course of the work of the cultivation office.

Cost Record The production record prepared in this manner is accompanied

on the same sheet by the abridged cost data for each division, and for the whole plantation under main accounting heads. This portion concludes with the total cost per ton cane, and per ton sugar, including reaping and cartage. All farm and divisional costs are accounted for, including staff, but excluding management and central office charges.

FARM AND FIELD RECORDS 315

Territorial Production Surveys The type of record just described meets the requirements of a

large single plantation, but where a number of such units are established within a country, some form of annual regional production survey is necessary. The collection and compilation of the returns which are needed for the preparation of these reports usually devolves upon some authority who may be appointed by the Government, or act under the aegis of an association representing the whole industry, or a definite and sufficiently important section of it. The annual " Cane Yield Survey " conducted in Jamaica since 1934 for plantations with which mills are associated is an example of this type. It provides a yearly summary of cane production for two-thirds of the total output, the other one-third being grown by farmers who are registered as suppliers to particular factories but who in most cases cannot submit sufficiently accurate returns to enable acreage yields and other data to be computed.

Cane Farmers ' Records—Jamaica Records of individual farmers' deliveries to the mills are used to

complete the annual statistical representation of cane and sugar production. Under the provisions of the Sugar Industry Control Law, the millers are required to supply to the Control Board a statement showing the total amount of cane received from each registered farmer. These figures are then used for the compilation of returns which divide the suppliers to each mill into categories arranged in quantity groups—less than 50 tons, over 50 and less than 100 tons, and so on. The final statement shows the number of suppliers in each group, the deliveries of cane for the group, and the total number of suppliers and their deliveries, in respect of each mill. Grand totals of fanners and deliveries for each quantity group are also shown. Mill figures enable the quantity of sugar obtained from farmers' canes to be computed. The object of this work is to maintain a check upon the registration of farmers and the contribution they make individually, by quantity groups, and as a body, to the production of cane and sugar. The absence of any information regarding the actual area cropped by each grower makes it impossible to determine the cane yields per acre. It would be of great advantage if growers delivering 100


tons or more were required to state the actual area cropped. Some arrangement would be necessary to make checks on the ground of a proportion of the areas, but any expenditure of effort for this would be amply compensated by the value of the information obtained. It should not be difficult to ascertain the varieties cropped by the farmers by noting them on the weight tickets issued at the time of receipt of the cane. The further desirable step of securing records of quantities of plant and ratoon cane would soon follow, especially for the larger farmers.

Value of Statistical Records Reports based on compilations of the types discussed are of

inestimable value to all engaged in the industry. The figures have a practical importance which impinges upon the individual planter, farmer, or grower, affecting his programme of production. Those charged with duties related to research, investigation, and instruction plan much of their activities on the trends of the industry disclosed by study of the statistical data thus obtained. Planters' associations are greatly assisted in their work, and official administration of agricultural industry in its relation to cane sugar production and disposal cannot effectively proceed without this knowledge.

Cane Yield Survey—Jamaica The annual cane yield survey is now conducted by the Research

Department of the Sugar Manufacturers' Association, with the co-operation of their members who own or represent the owners of the 24 operating " estates." The management of each estate is supplied with books of printed forms, on which the required particulars for each field are entered. The completed statements are forwarded to the statistician of the Research Department as soon as possible after the finish of the crop. They are carefully examined and doubtful figures questioned before the statistical abstracts are compiled. The information supplied for each reaped field is comprehensive, and includes :—

(i) Field identification, and area in acres and decimals of an acre,

(ii) Variety of cane. (iii) Class of cane. (Fall or spring plants ; or 1st, 2nd, etc.,

ratoons.)


From mill data reduced to 960 pol.

(iv) Date of planting, date of reaping, and age in months at reaping,

(v) Manures used, nature and quantity, (vi) Tons of cane reaped,

(vii) Tons of cane per acre, (viii) Tons sugar extracted

(ix) Tons cane per ton sugar (x) Tons sugar per acre

Item (v), manures, includes farm yard manure, filter mud and artificials. Item (vi) is the weight recorded at the first weighing station, which may be at a loading station or at the mill. It is not always the same as the mill or factory weight because of line losses. Hence No. (vi) divided by No. (viii) does not in every instance give the figure for item (ix). It will be observed that properly recorded field weights are essential. The cane figures are, however, readily compiled because all harvesting operations—reaping, loading and transport—are paid for at rates per long ton, so that the necessary figures for determining field yields of cane are available.

Method of Presenting Data—Jamaica The mass of data thus obtained is compressed into a number of

tables which provide data in respect of each estate, and totals and averages for the whole. These tables are supplemented by diagrams and brief commentaries on important points. The survey excludes all matters of cost, nor is it concerned with operational details. It does, however, present all material information regarding varieties, yields and fertilizer practice, and provides over the years a history in figures in an easily understood form. The tables include 10-year period comparisons of cane crops for estates and purchased cane; proportion of area under different varieties; tons of cane per acre ; and fertilizer practice. Shorter period comparisons of sugar yield are given with annual statements regarding varieties grown on each estate ; ratooning power of varieties ; percentage of averages in fall plants, spring plants and ratoons ; and yields of principal varieties.

Agricultural Intelligence Service The planter often views with distaste the increasing multiplicity

of returns he is compelled or invited to supply to various

310 -AGRICULTURE OF THE SUGAR-CANE

authorities. He naturally regards information relating to his plantation as his own personal affair, and is sometimes reluctant to disclose much of it to anyone else, even if he has data available to do so. This outlook has undergone progressive change during recent years as a result of economic pressure which has impelled state action for the protection, encouragement, assistance and development of agricultural industries, and has brought about the formation of numerous associations for the help and protection of their members. Neither the State nor the associations can serve planters to the greatest advantage unless they are kept supplied with essential, accurate and up-to-date facts about planters' operations and results. The effective conduct of international negotiations and the operation of trade agreements are dependent upon recorded statistics and descriptive reports compiled from large numbers of returns, and derived from observations and investigations made by competent officers. Internal administration in relation to agriculture and associated industries is also dependent upon the ready supply of correct information by those engaged in them.

Under the two main heads—external and internal affairs— there are numerous ramifications which lead to and from the planter. The channel of contact is often through a recognized association, a method which has proved of the highest value. The basis of the whole agricultural intelligence service is a detailed knowledge of the planters' affairs recorded and available in a form helpful to himself as well as to those to whom it should be supplied. Farming has always been an art which later developed into a business. In modern times it has become an applied science, which may be termed the practical use of organized knowledge. If continuous, accurate and properly planned records are not kept the planter may be sadly deceived as to his real profit or loss, and lack essential information about waste of effort and material, while possibilities of improvement will tend to be overlooked and advancement retarded.

Weather and Climate Among the numerous factors which affect the growth of cane

and the production of sugar are those comprised in the terms, weather and climate. Apart from their influence on the growing


crop, they have to be taken into account in connection with agricultural practices designed to enable the soil to produce maximum yields under the conditions of any particular district. The atmospheric conditions prevailing at any given time produce weather, and the general nature of weather in turn determines climate. Although weather and climate are uncontrollable except within very narrow and localized limits, such as by the use of overhead irrigation or the planting of wind breaks, investigations on the growth of any crop cannot ignore the wide range of observations which go to make up the science of Meteorology or Climatology. Careful and prolonged study of these matters is essential to successful crop production. An outline of the uses and possibilities of meteorological observations in connection with sugar-cane will therefore be helpful.

Rainfall Although rainfall may be regarded as the most important single

factor influencing the growth of sugar-cane, unless it is accurately measured by standard instruments set up under proper conditions the data obtained is of no value. Instances have come to light where rain gauges have been used with measuring glasses of incorrect size, where the gauge has been set up near to buildings, trees, or other obstructions likely to interfere with the free fall of rain into the gauge, and also where the top circle of the gauge funnel has not been level. In other cases the funnel spouts have been found to be choked with leaves or debris, while with one or two the water containers were found to be damaged and leaking. However carefully the water collected in the containers may have been measured, under such circumstances the figures obtained bear no possible relationship to the actual rainfall, and no significance whatever could be attached to them.

Close attention is necessary therefore to the type of gauge used and the measuring glass used with i t ; and the setting of the gauge well clear of surrounding obstructions in such a manner as to collect rain only. Any splashing from the ground which might Obtain access to the funnel must be avoided.

In order to be of use it is essential that all meteorological observations taken on plantations should be strictly comparable. This particularly applies to rainfall records, and in order to assist


those who may be setting up new gauges, or re-setting those already established, the following summary taken from the Meteorological Observer's Hand Book, 1942, published by Her Majesty's Stationery Office, London, is presented.

Emphasis is placed on the fact that in order to have comparable observations of rainfall at different stations the exposures of the rain gauges must be strictly comparable. A level site is essential, and slopes, terraces, walls and similar places must be avoided. On no account must the gauge be placed so that the ground falls away steeply on the side of the prevailing wind. In order to avoid interference from surrounding objects the distance of the gauge from them must be not less than twice the height of the object above the rim of the gauge. A position reasonably sheltered from wind is preferable to an exposed one, and if necessary the gauge may be set up in a position where it is protected from strong winds by a belt of trees, buildings, or other objects, provided the rule mentioned above is strictly complied with. If such protection is not possible, a level stretch of ground in a slight hollow may be selected. In the instructions referred to it is stipulated that the gauge should be set up so that its rim is level. This is essential. The statement goes on further to say that the rim should be 1 ft. above the ground, which should be covered with short grass. Under the conditions which are encountered in most cane-growing countries there is risk of the splashing of water from the ground into the gauge during periods of heavy rainfall if the rim is only 1 ft. high. The height should therefore be 2 ft. The instructions apply to the conditions of a temperate climate, and though in general they are more widely applicable, slight variations seem, necessary to cope with high rates of precipitation.

Methods of land preparation, cultivation, drainage, and irrigation, are not only related to soil types, but also to rainfall. Questions of the control, conservation, and disposal of soil water arise. The nature and extent of drainage depends on the quantity of rain falling directly upon the particular area under consideration and upon the fall in adjoining districts from which the drainage has to pass through that particular land. The water deposited on the soil in the form of rain is disposed of by ground absorption, absorption by plants, run-off and evaporation, including transpiration. Rainfall bears a direct relationship to the quantity of irrigation


water available from surface and underground sources. The proportion of each form of distribution varies widely. Studies of the disposal of rain water under various conditions have been conducted in the U.S.A., India and other countries. It is estimated that in India 35 % of the gross rainfall passes into the sea and 65 % into the air, the soil and plants, but wide variations occur.

Average Rainfall By having a number of properly sited rain gauges on a planta

tion it is possible to obtain a close idea of the average rainfall experienced over the whole area at any given time or for any period. This, however, is not obtainable from the arithmetical average of the rainfall recorded by each gauge, unless each individual gauge represents the same area as every one of the others. Each gauge should be regarded as representing a definite area, the total area represented by all gauges being that of the whole plantation. In order then to obtain the average fall for the plantation, the the rainfall recorded from each gauge should be multiplied by the area of land which that gauge is supposed to represent. The figure obtained will be in terms of acre inches of rainfall. By adding all these figures together and dividing by the total acreage the average rainfall in inches will be the result. It will be found that almost always this figure will differ from the arithmetical average which is normally quoted as the rainfall for the particular estate concerned.

An example of the effect of this method of calculation upon average figures obtained in the usual way is given below.


Even by this method the figure obtained for average rainfall can only be approximate. It is, however, sufficiently close for practical purposes. To obtain true average figures records for 30 to 35 years are necessary.

The ordinary rain gauge can only be used for measuring the total amount of precipitation between the periods of observation, which should in normal circumstances be at least daily. If it be not possible to make daily observations, then weekly rainfall records even when obtained under the best conditions with accurate and properly sited gauges are not of great help unless they are supplemented by visual observations of the approximate duration of the rainy period and the time of day at which it occurs. Moreover rain showers are often very local and, unless there is a sufficient number of observation points on and near an estate, a close estimate of the average fall is not possible. There should be at least one gauge to every 500 acres based upon the total area of the estate, and not the area devoted to sugar-cane only. In cases where it is not possible because of the remoteness of the recording station to make daily observations, a type of rain gauge suitable for weekly records can be set up.

Irrigated Land In areas where cane is grown by irrigation the careful recording

of rainfall and all matters related to it are of high importance. Experience has clearly shown that in such districts drought years depress the yields of cane despite the ample application of irrigation water, for the reason that the salts carried by the irrigation water are deposited in the soil where their concentration may accumulate to a point deleterious to the growth of cane. The quality of the cane is invariably better in the year succeeding one of normal or excess rainfall.

Visual Observation The records of rainfall obtained by accurate reading of quan

tities of water collected in rain gauges properly sited and distributed over an estate should be supplemented by visual observations. Apart from the time and duration, the direction from which the cloud comes, and the wind force at the time of the rain storm should be noted. Field staff should be encouraged to note such


observations, together with others, in the course of their ordinary work, keeping records in their field note books.

Closely related to the subject of rainfall is the extent of cloud in the sky, the type of clouds, approximate height, and direction from which they are coming. Such observations are of general importance in connection with the recording of weather. Whenever notes of these phenomena are made it is essential to record the time. This applies indeed to all meteorological observations. Where instruments are used, the particular one under discussion at the moment being rain gauges, the rainfall readings should be taken at the same time every day. When this is being done, attention can be given to the other points of visual observation. These can be supplemented throughout the day, or even during the night as opportunity occurs and changes arise.

Important Meteorological Elements It is hardly possible to separate one particular set of meteoro

logical observations from the others. All characteristics of weather have their influence on the growth of crops, but it is not possible for every observer to keep a close record of all of them. It is, therefore, necessary to decide which are of the greater importance, and as far as possible to stick to them, keeping some form of continuous day to day record. Apart from rainfall and related phenomena, the important factors are air and ground temperature, humidity of the air, duration of sunshine, presence and extent of cloud, wind direction and force, and evaporation.

Measurement of temperature can only be made by the use of the thermometer. As a general rule such records would be obtained from a central station, but the observations there made can be supplemented by the reading of properly placed thermometers suitably exposed in other places. As well as the actual thermometer readings at set times each day, it is desirable to arrange for daily maximum and minimum readings for which purpose special though inexpensive instruments can be obtained and set up near to the ordinary thermometer. The personal observations made by members of the field staff and others would then supplement the readings obtained at central stations of standard pattern with proper exposure.

Humidity can be measured at the usual set times by the use of


a wet and dry bulb thermometer, but determinations will be misleading unless great care is taken to comply with the general instructions for the use of such instruments. Continuous records of temperature and humidity obtained by special instruments are best derived from a central station with a trained permanent observer. Sunshine records are also important and should be obtained from a standard form of instrument at a central station.

Wind direction and speed should be observed, preferably with recording apparatus at central stations, but also by visual methods using the Beaufort Scale.

All thermometers are housed in a small ventilated chamber known as a Stevenson screen, which can be erected on the same site as the rain gauge, wind recorder, sunshine recorder and evaporation tank if all these are being used.

Meteorological Stations

The nature and extent of the observations, and the methods for making them, are related to the area to which they refer and to the local variations in weather. In a continental area with extensive stretches of land displaying uniform features, such variations between contiguous districts are usually less marked than in islands and mainland territories with mountains, hills, valleys and coastal plains closely associated with one another. Thus the number and equipment of meteorological observation points for an area of given extent will vary. While no generally applicable rule can be laid down, a minimum of one station for each 500 acres of a sugarcane plantation is desirable. The actual area to which each station refers and its location will depend upon local considerations, and even in extensive uniform runs of land it is unlikely that a chequer board system will be possible.

Types of Station

The particular needs of sugar-cane plantations and of the districts in which they are situated are similar in major respects to those of agricultural areas generally. All instruments used should be thoroughly reliable and supplied by a firm which specializes in the manufacture of meteorological equipment. It is essential that they be properly set up and used by trained ob-


servers. Periodic checks should be made to determine and correct errors of readings and recordings.

Three types of station are required, of which two are suitable for plantations, and the third for a central observatory serving an extensive area.

Type i.—Suitable for smaller plantations, with one station to each 500 acres.

Observations to be made :— Rainfall—daily in cane areas. Weekly in contiguous land. Temperature—maximum and minimum, a.m. and p.m. Visual records of sunshine, cloud, wind direction and estimated force, to be taken at same times as temperature readings.

Type 2.—One station for a large plantation, with" Type 1 installations for each 500 acre subdivision.

As for Type 1, with the addition of:— Humidity—a.m. and p.m. Soil temperatures—a.m. Sunshine—by recorder.

Type 3.—One station for a group of plantations in a defined climatological area.

Rainfall (a) with standard gauge, daily (b) with recording instrument giving total precipi

tation, rate and duration. Temperatures—maximum, minimum, soil and grass minimum. Humidity. Wind—Direction and estimated force at stated observation

times. Sunshine—by recorder. Evaporation.

Type 4.—A central station established to serve an extensive area in which there are sub-stations of other types. An observatory of this description would be under Government control, or under that of an Agricultural Research Organization.


Temperatures—maximum, minimum, soil and grass minimum.

Interpretation and Utility of Records Stations of types 1 and 2 can readily be used by plantation staff,

by whom observations are made, compiled and studied. Observers should be competent, and be required to carry out this work as a part of their normal duties. It is desirable that records be freely exchanged among all planters in a cane-growing territory and forwarded to a central bureau for close study and interpretation. The bureau may be the research headquarters, the public meteorological service, or some other organization responsible for the work. The utility of the mass of figures obtained depends upon their careful examination, the inferences drawn from them by competent experts, and the distribution of the desired information to those engaged in the industry.

Weather conditions represent a group of important factors which enable soils under proper cultural and nutrient treatment to grow crops. Their study is, however, but one part of the whole subject of crop production and agricultural economy. The ability of plants to take up nutrients depends to a great extent upon soil moisture conditions, and water movement in and through the soil, which factors are influenced by rainfall. The proper planning of drainage systems entails a detailed knowledge of rainfall.

The selection of varieties of cane suited to particular environmental conditions involves a study of weather, and in particular the elements of rainfall, temperature range, and evaporation. The germination, rate of growth, and maturing of cane are affected by general meteorological conditions, while crop prediction and reaping programmes must take those factors into account. Irrigation practice to be successful must be related to meteorology, more especially to rainfall and evaporation including transpiration.

CHAPTER 17

CANE FIRES AND THEIR CONTROL

Damage by Fire The possibility of loss and damage by fire to standing cane is

probably the greatest risk to which a sugar-cane plantation is exposed. In the early stages of growth of the cane the fire risk is negligible, except with ratoons in fields with dry trash, but as it begins to approach maturity and dry out, a fire once started becomes extremely difficult to bring under control and extinguish. Although the firing of cane is in many places a normal plantation practice immediately before the crop is reaped, this is undertaken under conditions which usually enable the planter to prevent spread beyond pre-defined limits. Even in these circumstances the greatest possible care is essential to prevent accidental spread by airborne burning material to adjoining fields. Burnt cane reaped and processed within 24 hrs. of being fired undergoes no commercial loss, but any delay beyond this time brings about rapid and progressive deterioration which causes difficulties in extracting the sugar and resultant losses to the planter and miller. The regulation of deliberately set cane fires immediately prior to reaping is greatly assisted by the precautionary measures which can be taken to limit or prevent the spread of accidental fires.

Precautions The first essential is the careful planning of the whole plantation

area followed by planting and reaping schemes which will assist in isolating the different areas of cane most prone to fire into blocks which are separated by other blocks in fallow, young cane, and reaped fields, without interfering too much with the economical operating layouts discussed in Chapter 8. If, therefore, it is' feasible so to arrange the whole planted area in a rough chequer-board fashion, an outbreak of fire can more easily be confined. This suggested arrangement should form part of the various considerations which decide the general planning of the area, and the planting and reaping programme. The deliberate firing of the trash blanket remaining on the field after cane has

Y 327


been harvested is often conducted to facilitate the ratoon cultivation, including fertilizing and the application of water, as well as when the particular fields where the trash is fired are thrown out for replanting. Again the planter conducts this operation in such a manner as to keep the fire under control and limit the possibilities of damage to surrounding areas in cane.

Intervals and roadways in the cane areas should be laid out and maintained to give speedy access to all parts of the planted area. Where irrigation is used, convenient points can easily be arranged in the distribution system, whether it be by open ditches or pipes, for the supply of considerable volumes of water in emergencies. The practice of " trashing " the cane, i.e., the stripping of the dead leaves, is not so widely conducted as formerly, but as fields approach maturity and the risk of fire increases, it is a useful precaution to trash the cane on the outer edges of the field to a depth of perhaps 25 ft. While this does not altogether make it impossible for a fire to spread from the e dge of the field, where outbreaks usually start, it will in normal circumstances check the rate of spread which will be slower through the trash on the ground than it would be if the dead leaves still adhered to the cane stalks, and so give more time for it to be brought under control before it reaches dangerous proportions. The maintenance of intervals should include regular cutting back and removal of grass and weeds, which in any case is a normal plantation operation.

Smoking and Other Causes of Fire Accidental cane fires are usually the result of carelessness and

inattention to estate regulations. In all well-organized sugar-cane plantations smoking in the cane fields is strictly prohibited, but some relaxation is allowed in open fields in fallow, being ploughed, or in young cane which has not covered down. The difficulty here is that the tacit approval of smoking in some parts of the area invariably leads to the practice in others, and it appears better to impose a general prohibition against smoking in any part of the plantation where cane is growing or is to be grown. This should apply to everybody whether they are at work, visiting, or inspecting, and should be strictly enforced. It is a widespread custom for field labourers to cook or heat their food over small open fires usually made on the side of intervals and roadways.

CANE FIRES AND THEIR CONTROL 329

These constitute an exceptionally grave risk, and field staff should make suitable arrangements to limit the places where fires can be made, to regulate their use and to have them completely extinguished after the meals have been taken.

Serious cane fires have arisen through faults in electrical transmission systems traversing cane areas. Damage to overhead lines may occur through the falling of branches or the overturning of trees near to them during high wind storms. The remedy though obvious, is not invariably applied. Repair gangs working in the fields using portable forges, blow torches and other high temperature equipment are a potential though not considerable danger. They should, however, be made fully aware of the fire risks attendant upon their normal work and should, like all other field operators, observe the estate regulations in respect of precautions against fire. Another hazard is the steam locomotive operated tramway or railway system, and even diesel engines can start fires under very dry conditions by sparks emitted in the exhaust. Any ash producing fuel in steam locomotives is highly dangerous, although plantation engines are so fitted as to minimize the risk of fire being caused by them. The tracks and sidings to a suitable distance on each side from the rail centre should be kept clean and free from easily combustible material. Heavy discharges during electrical storms can easily cause fire to break out in standing cane. As a general rule, however, these storms are accompanied by rain, which limits the amount of damage, though the effect of lightning upon cane is still very marked.

Malicious Fire-Setting The fire risk in cane fields is always greatest immediately before

and during the harvest period. Where large numbers of people are employed, fires are occasionally deliberately set for various reasons by irresponsible or dissatisfied malicious labourers. These conditions offer perhaps one of the greatest problems in the management of operations. Fires of this description often occur at points where it is difficult to bring them under quick control and so limit their spread. The incidence of such fires increases when the unskilled labourers are in a state of unrest through dissatisfaction or deliberate incitement by agitators, when precautionary measures have to be increased.


Fire Control Organization The plantation organization should include arrangements for

the prompt detection, reporting and location of outbreaks, and for the speedy transport of control gangs and equipment to them. The fire control organization for the fields should be modelled on and associated with that for the plantation buildings. Regular watches should be maintained and a reporting system arranged combined with a suitable method of giving a local or general alarm when necessary. The fire duties of staff and skilled workmen should be carefully defined and duty rosters arranged. It should

< be a condition of employment that all labour within easy reach of the scene of the fire should turn out to render such assistance as may be possible under the directions of the fire control staff. In

I some places it is a legal obligation for workpeople to proceed immediately to a cane fire and help energetically to extinguish it.

Fighting Cane Fires The fire fighting equipment of a cane plantation is often limited

to the tools normally used by the labourers, particularly cane knives. If heavy tractors, and motor pumps when water is available, can be got out in time they provide effective methods of making fire breaks either by pushing over the standing cane or by applying water, in each case at a distance from the centre of the fire along the line of its approach. This distance will to some extent be governed by the intensity of the fire, which in turn is determined by the condition of the cane ; and the wind direction and force. Where convenient field intervals and roadways provide natural fire breaks, a decision must be taken quickly in regard to the wisdom of attempting to confine the fire to part of the field in which it has occurred, or to concentrate upon cutting down or

1 pushing over the cane in adjoining fields to extend the width of ' fire break across the general direction of its movement.

The normal methods of fire fighting in sugar-cane fields are I well known to estate staff, but there are supplementary methods

which can be usefully employed including some already men-5 tioned. In irrigated plantations greater use of the available water j for fire control could be made through the medium of mobile , pumping units of various sizes with tank capacities up to 2,000 I gal. These might be in the form of trailer mounted tanks and •'i

i

5

CANE FIRES AND THEIR CONTROL 331

motor pumps capable of being hauled to the scene of the fire by wheeled tractors or other estate transport units. After discharging their water they would be quickly refilled at the nearest supply point in the irrigation system. Their usefulness would be limited under windy conditions, but in circumstances under which they could be safely employed they would apply water to strips of cane on the boundaries of fields threatened by the spread of the fire. They would not be suitable for applying water to the actual area of the fire except in cases where this was very small and the outbreak spreading extremely slowly and near to the edge of the field.

Notice of Intentional Fires The fire control arrangements for a plantation should include

the notification to the management and to the fire control staff on duty of intention to burn fields of cane or trash. Such information should include the location of the field and the proposed time of firing, and should usually be given 24 hrs. before the setting of the fires, the object being to alert the responsible staff and to prevent fire control measures being put into operation unless they become necessary through unintentional spread of the deliberately set fires.

Insurance It is usual to insure against plantation fire risks, the object

being to cover the insured party against loss through a major calamity rather than to reimburse him in respect of minor damage. Except under particularly adverse circumstances it is usually possible with effective reporting and control to extinguish a cane fire before it has caused extensive loss. When fires occur during the crop period the fired cane is reaped as quickly as possible and sent to the mill, with no appreciable loss to the planter, and in most cases no claim is made upon the insurer. The position, however, is different if fire damage occurs during the out of crop period, when the fired cane becomes a total loss. It must in any case be reaped and removed from the land in order to allow the succeeding ratoons growth to develop, or if the field is due to be thrown out to permit the normal operations of preparation and planting to proceed. In such cases a planter may claim upon his insurers, though as a general rule he will probably not do so if the damage and loss are small.

CHAPTER 18

METHODS OF COMPUTING THE PRICES OF CANES 333

The weighing, and sampling of the cane and first expressed, juice, are very carefully conducted. Fibre cannot be determined on every sample. The Cane Prices Board prescribe the system to be used by each mill for ascertaining the fibre in consignments for the purpose of C C S . calculation. It depends upon the classification of canes into various groups for fibre analysis of samples. Payments are made in accordance with a scale fixed by the Cane Prices Board Award for each mill which takes into account differences in C C S . and prices of sugar. Usually the farmers receive payments based on an interim sugar price during the crop period, an adjustment being made after the end of the season.

The method though based on assumptions and arbitrary factors, works well in practice. Certain improvements are under consideration, one of which is related to the effect of dirty and trashy cane. At present no allowance is made for extraneous matter. After the adjustments have been made the grower receives about 70% of the raw sugar realization. He delivers his cane to the nearest point of delivery to his farm. If this is on a 24-in. tramway, loading is paid for by the grower. He also pays rail freight if the distance to the mill exceeds 20 miles. The cane is weighed at the mill. Members of the Cane Testing Staff of the Cane Prices Board attend at all mills to ensure that the prescribed methods are followed, and decisions of the Board put into effect.

South Africa—Natal The sugar industry in Natal is regulated and controlled

by the Sugar Act of 1936. The principal provisions are the power given to the Minister of Commerce and Industries to give the force of law by publication in the Gazette to agreements entered into under specified conditions by growers, millers and refiners, and for the establishment of a board to give effect to such agreements. Agreements between growers and millers must have the prior approval of 90% of the growers who represent 90% of the total production of cane by growers during the previous calendar year, and of millers who have manufactured not less than 90% of the total sugar produced during the same period. The Minister has power to require the inclusion of matters affecting the sugar industry in agreements. Among the types of agreement included i s " a formula for determining a base price of sugar and


for fixing on the basis of such base price, the prices to be paid for sugar-cane by millers to growers." The Sugar Industry Agreement, 1943, amended in 1948, came into effect by the publication of Government Notices in those years. The chapter headings are :—I Central Board ; II Control of Production; III Supply of Cane and Cane Price; IV South African Sugar Association and Disposal of Crop, with schedules dealing with matters related to determination of prices payable for cane. The constitution and powers of the Sugar Association are included.

In this way the whole industry operates under freely negotiated agreements which have legal effect after approval by the Minister and publication in the Gazette.

The price paid for cane is governed by the amounts received for the several different grades of sugar manufactured from it, reduced to a common basis of price in terms of raw sugar of 960

polarization. All white sugar including refined is valued at the same figure, 960 pol. sugar being arbitrarily priced at £4 per ton less. The " net price basis 960 " for refined sugars is arrived at by deducting three other charges from the price of refined sugar per short ton. These are :—

(a) Certain statutory payments for sea freight to Cape ports, railage ; and industry obligations including the Experiment Station.

(b) Railage from mills to Durban to equalize rail charges. (c) An amount for supplementary payments to growers.

The " net price basis " for No. 2 grade, and for export sugar are also calculated by deduction of the same levies and other charges. In this way the net price basis 960 for all sugars is obtained from the proportions and price of each quality sold. From this the price per ton sucrose is calculated by multiplying by a factor which represents the relative cost of growing as compared with milling on the assumption that mill overall recovery is 76%. This factor was .509291, but has been increased by arbitration on the grounds that the new varieties of cane grown since 1936 are of greater value to the miller than Uba, which was the principal cane when the earlier figure was settled. Additional payments are made by the millers from amounts derived from certain levies and reserves. There is a differential between the payments to the millers and


growers for sugar produced from cane grown by the former on the ground that their agricultural operations are less costly for various reasons. The supplementary price payable to growers decreases with increase of production in accordance with a simple formula, for the reasons that large-scale production is cheaper than small-scale, and to encourage small growers. In a recent year the supplementary payment per ton ranged from approximately 4s. 4d in respect of 1,000 tons, to 6d. per ton for 15,000 tons and upwards.

Cane is delivered to the mill or to specified points by the grower at his expense in agreed proportionate quantities throughout the season, subject to any special arrangements. It will be realized that the payment for cane delivered is based upon its sucrose content. In effect the grower receives payment for sucrose, which for convenience is calculated in terms of cane. The regulations governing these matters are specific and comprehensive. They provide for methods of sampling and analysis, facilities to be provided by the miller, proportion of consignments to be sampled, the weighing of cane, and weighing and measuring devices for juice and water in the factory. The Central Sugar Board maintains a testing staff, members of which are provided with independent laboratories at the factories unless a majority of 70% of the growers supplying do not require a full service, in which event mutually satisfactory testing arrangements may be made. Growers must undertake to deliver the different varieties of cane in separate consignments, as far as possible, and millers to weigh them separately. Crusher juice purity and sucrose content are determined on the different varieties thus delivered. Growers, through their Mill Boards " have the right to participate in filter press cake residual." The grower pays the cost of loading and delivery to his farm. When molasses exceeds a value of .625d. per gal. f.o.r. at the mill, growers have the right to share the excess with the millers in accordance with determinations made by the Central Sugar Board.

Jamaica The evolution of a regulated system of payment for farmers

canes supplied to factories in Jamaica occurred by several stages during the period 1938 to 1944, since when there have been changes of a minor nature brought about by altered conditions


applying to certain factories. Prior to 1938 the " independent" growers comprising substantial cane farmers and small cultivators received varied prices for cane irrespective of quality. The large suppliers were often under contract with the nearest factory, arbitrary rates of payment being agreed upon which usually provided for a guaranteed minimum price per ton or alternatively a percentage ranging from 5 to 6¼% of the realized price of bulk sugar 96° pol. at the factory. That is, the sugar value for payment on a percentage basis was determined by deducting all charges for bagging, handling, transport and shipment from the realizations on sugar. Some contracts were negotiated annually ; others continued for longer periods. All other cane was purchased at an " open market" price announced by each factory. Though persons not under contract were free to deliver to any factory which would receive their cane, there were few who could make a choice because of distance and cost of transport. Occasionally a " bonus " or additional payment was made.

The Sugar Industry Control Law of 1937 provided, amongst other matters, for the registration and control of cane farmers supplying to factories, and for the fixation of prices to be paid for cane should it be considered necessary in the public interest. The former was immediately put into effect, and farmers were registered as supplying to their selected purchaser. The " Jamaica All-Island Cane Farmers' Association " formed in 1941, became a statutory body by a special law passed in the same year. The designation " farmer " is used in a very wide sense, and includes peasant growers with small cultivations and deliveries of a few tons or even less. This Association and the Sugar Manufacturers' Association attempted without success to agree upon a formula for determining prices to be paid for cane. The following year a Government order was published fixing the method of calculation to be used, based on the principle that the manufacturer should process the cane, deduct from the proceeds the cost of manufacture, handling and fixed allowances for depreciation and profit, and then pay to the farmer a rate per ton of cane arrived at by dividing the net value per ton of sugar unbagged at the factory thus calculated, by the number of tons of cane required to make 1 ton of sugar. Provision was included for a share of the byproducts value to be paid to the farmers. In effect this meant their


participation in the proceeds of the " Rum Pool." Though it was recognized that suppliers should be paid in accordance with the quality of their cane, the large numbers of very small growers made this impossible. The difficulty was overcome by arranging for individuals or groups supplying 1,000 tons or more of cane to be paid on the basis of the sugar yield of their cane, if they or the manufacturer so requested. Objections to the formula were raised by both farmers and manufacturers who subsequently agreed in 1944 upon a different basis, which is now used with later modifications in respect of particular factories where conditions have changed. The effect of this is to define clearly on a percentage basis the net value of sugar on which cane price calculations for deliveries to the particular factories shall be made. Large factories of high efficiency are rated above smaller ones. The net value of sugar, called " the net stripped value " is the actual value of sugar in bulk at the factory. The farmer receives for each ton of cane delivered an amount determined by dividing the agreed percentage for the particular factory of the " net stripped value of sugar " by the number of tons of cane required to make 1 ton of sugar. The latter figure is ascertained individually or by groups as already mentioned. In addition to the " cane value " thus calculated, the manufacturer pays for each ton of cane one-half of the amount per ton of cane milled which he receives from the rum pool. In other words, farmers participate in the by-product value of molasses to that extent.

The method is by no means ideal, and can only be regarded as a working compromise. The principle of payment on a basis of the amount of sugar the processor extracts from the cane penalizes the farmer supplying rich cane to a low-rated factory, so that growers of cane of the same quality receive different prices if they supply to factories which are not on the same percentage rating. On the other hand, the highly efficient large factory is rated higher than a smaller one which may be equally efficient. The system differs from that in Puerto Rico where the percentage of the value of the sugar to be used for calculating the farmers' price depends on the quality of the cane, and not on the rating of the factory. The " colonos' " or farmers' gross returns are calculated on 63% of the sugar value if the cane yields 9% of 960 sugar, rising to a maximum of 67½% with a yield of 13% or more. They also


participate in the amounts received for molasses. This is intermediate between the Jamaican system and the methods of Queensland and Natal which are based on the total sucrose content of the canes delivered.

L o u i s i a n a

The price paid for cane is determined for each crop. Four factors are involved :—

(a) Cane quality; (b) Raw sugar price as quoted daily on the New York Coffee

and Sugar Exchange during the crop period, from which the average price is computed ;

(c) The average price of blackstrap molasses ; and (d) The molasses yield per ton of cane as fixed for the crop.

The price of each ton of standard cane for 1951-52 crop was 106% of the price of 100 lb. sugar, plus one-half the realized price of molasses in excess of 6 cents per gal. on the basis of 6.9 U.S. gal. yield per short ton of cane. Standard cane is defined as cane in which the normal juice contains 12% of sucrose and has a purity of 77 %. The cane price varies upwards or downwards in accordance with the results of analyses made by the factory chemist. Trash tests are made, and the weight of trash is deducted from the weight of cane. The immature upper portion of the stalk, freed from leaves, is not regarded as trash.

CHAPTER 19

THE SUGAR-CANE AS AN INDUSTRIAL RAW MATERIAL

Outline of Sugar Factory Process The value of sugar-cane to the planter depends upon the pro

ducts which can be extracted from it for which a market demand exists at prices yielding a profitable return to the manufacturer. The principal of these is sucrose which is directly obtained from the cane and prepared in a suitable form for marketing, usually as refining raws of 960 polarization, which represents the basic market standard for this class of sugar. In some factories the processing equipment includes provision for the preparation of refined sugar which is almost pure sucrose. In the course of the manufacturing process the constituents of the cane are initially separated and some of them are changed in the passage through the various parts of the sugar mill or factory to materials differing in form from those originally present in the cane. The general average composition of mature sugar-cane is approximately:—

Water 70% Sugars 13.5% Fibre 14% Other solids 2.5%

The total solids in the cane reaching the factory amount therefore to an average of about 30% of the weight of material delivered. The sucrose, which is the sugar obtained from the factory, process by crystallization from the purified concentrated juice, represents by far the greater proportion of the actual sugars in the cane, part of which consists of what are called reducing sugars. These are not recoverable as crystallized products and mainly pass out with the by-product molasses, The milling or crushing separates the juice containing the sugars and other materials from the fibrous residue, known as bagasse, which generally provides the fuel required for steam and power in the factory.

The juice, which is an impure solution of sucrose, contains 339

34° AGRICULTURE OF THE SUGAR-CANE

dissolved and suspended matter obtained from the cane, including wax, part of the mineral matter and other non-sugars, which are separated by clarification. This involves the addition of some material to the juice, usually lime, which will coagulate the impurities and enable them to be separated by subsidence and filtration. The products of this are filter mud and clear juice. The clear juice is concentrated in stages and finally boiled under a high vacuum to a point at which the crystalline sugar is obtained. The sugar crystals are separated in centrifugal machines from the liquid which passes through the fine screening of the baskets and is known as molasses. Further crops of crystalline sugar can be obtained by reboiling the molasses and repeating the process of separation. The final or exhausted molasses still contains some sucrose which cannot be easily separated. The three direct factory by-products are therefore bagasse, filter mud and molasses, all of which are capable of use as industrial raw materials. Before dealing with them in this connection the uses of sugar may be briefly discussed.

Principal Uses of Sucrose Sucrose is principally employed as a sweetening agent, and as a

foodstuff. Apart from the domestic consumption for these purposes, large quantities are used in food manufacture, and may properly be included in direct consumption sugars. Sucrose cannot be fermented to produce ethyl alcohol or ethanol, commonly known as alcohol, until it has been changed into simpler sugars by the process of hydrolysis, which can be effected by treatment with mineral acids. This process, often called inversion, is used for the preparation of Brewers' sugar, which is one of several industrial forms in which invert sugar is used. Sucrose is also employed for many industrial and other purposes. Chemical research has disclosed that sucrose can form the starting point for the preparation of an extensive range of new chemical substances, as well as for some which were already known. The extent to which sucrose itself is likely to develop into an important industrial raw material depends upon the cost of the sucrose itself, the efficiency and cost of the manufacturing process for the preparation of products which are in constant demand, and the prevailing market price of those products.

THE SUGAR-CANE AS AN INDUSTRIAL RAW MATERIAL 341

It is not possible in the present work to deal fully with the numerous products of industrial value which can be derived directly and indirectly from the basic raw material, the sugar-cane. Extensive literature is available on the subject, in publications of the Sugar Research Foundation, New York, and in various journals. The outline by L. F. Wiggins, " The Chemical Aspects of the Sugar Cane " presented to the B.W.I. Sugar Technologists Meeting, 1948, and published in the proceedings gives a clear picture.

Sugar Factory By-Products Bagasse is the fibrous residue of the cane consisting largely of

cellulose, part of the minerals in the cane, and small quantities of sugars and other matter not separated in the crushing process. As the bagasse leaves the last mill it contains about 48% of water ; and a portion of it, sometimes the whole, passes in this form to the boiler furnaces. Extensive research has been conducted upon bagasse with the object of ascertaining the uses to which it can be put, apart from its value as a cheap and convenient fuel in the sugar factory. Modern sugar factories with their high fuel economy generally have large surpluses of bagasse. Its local uses, apart from boiler fuel, are often restricted to the preparation of compost and for direct application to the cane fields, both of which are employed as convenient means of getting rid of a bulky and troublesome waste product.

Insulating Board Some factories having such surpluses, and more conveniently

situated, are able to dispose of it for the manufacture of various forms of compressed fibre board, and in Louisiana several factories use fuel oil or natural gas, and dispose of the whole of the bagasse they produce to the Celotex Corporation, which established the fibre board industry in 1920 and now makes over 2 million sq. ft. per day. The companion plant in New Jersey, U.S.A., receives the plain product from the factory in Louisiana and applies finishes in accordance with market requirements. Asbestos cement boards are manufactured, which are cemented to both sides of a laminated cane fibre insulation board by means of special adhesive, producing Celotex Cemesto board, largely used for


quickly erected permanent construction. Associated with these organizations is the English Company, Celotex Ltd., which uses imported baled bagasse for the manufacture of insulating board. Two other large factories separately owned, are situated near Hilo, Island of Hawaii, and at Sydney, Australia. The products, of similar type to those manufactured by Celotex, are known as Canec and Can-ite, respectively. The manufacture of Vazcane fibre boards direct from sugarcane has been conducted on a comparatively small scale for many years in Cuba. In this process sugar extraction is regarded as of secondary importance.

Approximately 85 tons of bagasse, equivalent to half as much dry fibre, are required for the production of 100,000 sq. ft. of ½-in. compressed board, which quantity is regarded as the minimum economic daily capacity of a factory. Comparisons with the cost of other building materials, such as brick, tile asbestos cement, and plywood, show advantages in favour of various types of insulating board made from bagasse.

Paper Manufacture Considerable attention has been devoted to the possibiUties of

using bagasse as a raw material for the manufacture of various grades of paper. Bagasse is a cellulosic material consisting of strong flexible fine fibre mixed with pithy material which must be separated before it can be used for the production of good quality paper. A number of methods have been worked out for doing this, and fine quality of writing paper and newsprint have been prepared on a small scale. It appears, however, that under present conditions the costs of production of such types of paper from bagasse are much higher than those in which other sources of cellulose are used. For the manufacture of corrugating and insulating boards it is not necessary to remove all the pith and there are definite possibilities for what are known as boxboard and shipping containers. A factory with a capacity of 6,000 tons per annum has recently been erected in Natal, South Africa, for the manufacture of these products. Bagasse fibre can also be used for blending with soft wood pulp for the production of wrapping paper and bags. The rayon industry requires a uniform grade of alpha-cellulose which can be manufactured from bagasse.

F I G . 54.—A plantation shop, Clewiston, Florida.

[Courtesy of U.S.A. Sugar Corporation.

mmw? v* * j > , * > * * * * *

l.*h*-lM**J


Domest ic Fuel Briquettes for domestic fuel have been successfully prepared

from bagasse by a process which involves preliminary carbonization, mixture with a proportion of molasses, followed by compression and further carbonization. Modern equipment has been designed for carrying out a process on a commercial scale with an output of about 4,000 lb. of briquettes per hr., equivalent to the consumption of about 4.2 short tons of bagasse and 1½ short tons of molasses. W. Scott suggests that unbaled bagasse carbonized in a continuous retort, briquetted with molasses, and dried, would by this process yield a product of comparatively low ash content. By-products of the dry-distillation would be methanol and acetic acid.

Filter Mud and Press Cake This material, consisting of traces of sugars, wax, fatty matter,

other non-sugars and miscellaneous impurities in the juice, with lime and bagacillo or other filter aid substance, is removed in the juice clarification process as a dark greenish-grey precipitate of high moisture content varying from a little more than one-half to nearly four-fifths according to the particular processes used. T h e dry material is rich in lime and contains phosphates and nitrogen and most of the wax and fatty material originally present on the rind of the cane. In many places it is allowed to decompose in heaps and is then applied directly to the cane fields as a useful fertilizer.

The amount of crude wax in dried filter mud derived from unburnt cane may be as high as 15%. Burning the cane prior to reaping destroys some of the wax and causes discoloration of the residue remaining on the cane. The wax content of dried muds from burnt cane may be 10% or less. In the higher concentrations it is profitable to extract the waxy materials by the use of solvents, such as Benzene and Heptane. The crude wax can be purified from the fatty material associated with it. Pure cane wax is similar in properties to Carnauba wax, and can be used for various industrial purposes, including the manufacture of polishes and electrical insulating materials. The removal of the wax does not in any way impair the manurial properties of the mud. The world shortage of natural waxes has brought about a remarkable increase


in the market prices of Carnauba wax with which cane wax can now successfully compete for certain purposes, while commanding a price which makes its recovery attractive.

Molasses The final by-product which remains after the recoverable

sucrose has been separated is a brownish black highly viscous liquid containing up to about 63% of total sugars comprising sucrose and invert sugar, with other organic and inorganic material, including various mineral salts, among which is potash. The principle value of molasses lies in the sugar present. When diluted and the sucrose converted to invert sugar, it is readily fermented by yeasts of the saccharomyces group with the formation of ethyl alcohol (ethanol), small quantities of higher alcohols, and the liberation of carbon-dioxide. The potable spirit, Rum, is made by variations of this process, the alcohol being distilled in pot stills or continuous stills, matured in oak vats or casks, blended, and diluted with water to form the drinking rums of commerce.

When alcohol is produced for industrial purposes the process is essentially similar, but greater care is taken to use pure strains of yeast, and to remove as much of the non-fermentable material as possible from the molasses before fermentation. In this way higher yields are obtained, and the distillation process conducted in column stills, produces an alcohol-water mixture containing 96% of ethanol, from which pure or " absolute " alcohol may be prepared by further treatment with benzene or certain other volatile liquids by what is known as azeotropic distillation. Ethanol is itself a basic material for a wide range of chemicals.

The residual liquor after separation of the alcohol by distillation, known as distillery slops or dunder, can be used for the preparation of stock feed and fertilizer. It contains the potash from the molasses, and the dead yeast cells. The liquid is allowed to settle, the sludge being filtered and the filtrate added to the supernatant liquor, which is then concentrated under low pressure yielding a dark viscous liquid which is burnt. The ash contains about 37.5% of potash and can be used in the place of other potassic fertilizers. The filter cake is dried and disposed of for stock feed. In place of filtering, the sludge can be dried by steam-heated cylindrical film drier.


Under special conditions of fermentation, using different types of organism, the commercial production of Acetone, Butanol, Citric Acid, and Lactic acid can be effected from molasses. All these are extensively used. Lactic Acid can be prepared from pure sucrose and from molasses by chemical methods. It is largely used in the plastics industry, and can by chemical processing produce a synthetic rubber known as Lactoprene. The prospects of using molasses for the production of lactic acid depend mainly on price considerations, and it has been stated that should lactic acid from sugar or molasses be produced at a competitive price, market requirements would be capable of absorbing very large quantities.

Aconitic acid is the principal organic acid present in sugar-cane juice and it may be recovered in the form of its calcium salt from molasses without affecting the usefulness of molasses for other purposes. In the Raceland Sugar Factory in Louisiana the available aconitic acid is removed from the " B " molasses, the latter being passed back to the sugar process. The extraction plant is used for processing final molasses from other sugar factories during the out-of-crop period. The plant recovers about 10,000 lb. of calcium aconitate per day. The presence of aconitic acid in sugar-cane juice is related, amongst other matters, to the degree of maturity of the cane. In Louisiana the aconitic acid content of molasses is 3.5% by weight, and about one-third as much in Puerto Rican molasses. Aconitic acid can be used for the manufacture of plastics and synthetic rubber. The growing demand has led to the suggestion that investigation should be made of the economics of production of aconitic acid from cane grown specially for the purpose and reaped at short intervals in an immature condition. This might be combined with the utilization of cane fibre.

Food Yeast Molasses is used to a limited extent for the production of food

yeast, Torulopsis utilis, which is high in protein content and rich in vitamins, particularly those of the important B1 group. This yeast is of great use in malnutrition and for the correction of vitamin deficiencies in human food. It came into prominence during the 1939-45 World War, when it promised to provide a


much needed protein foodstuff containing a high proportion of vitamins. The process for growing the yeast from cane sugar and from molasses was worked out and a factory was erected for commercial scale production at Frome in Jamaica near to the large sugar factory there. Another plant of similar capacity in Puerto Rico produces both Torulopsis utilis and Brewers' or Rum Yeast, Saccharomyces cerevisiae, the object being to examine the possibilities of both types of yeast for human and animal food. Another small Torula yeast plant is operating mainly for investigation purposes near Durban, South Africa.

At present the market possibilities of food yeasts are limited by cost considerations. Both types of yeast appear to have great future possibilities if the cost of production can be more closely related to that of comparable foodstuffs. Torulopsis utilis is marketed in the form of a very fine dry powder containing approximately 9% of moisture; ¼ oz. per day is stated to provide the vitamin requirements of a normal adult, while larger quantities can be consumed as a protein food, usually mixed with other suitable items of diet. As a source of protein, sucrose is superior in yield on an acre/time basis to any other form of protein vitamin food. Sucrose yields about half its weight of dried food yeast. Under tropical sugar-cane production conditions 1 acre can therefore provide an average of 1½ tons or more of protein per annum. The importance of cane sugar from this point of view may greatly increase in the future because of the increasing demand for protein foodstuffs, already in short supply for the growing population of the world.

Approximate Values In this brief sketch of some of the possible uses of sugar-cane

as an industrial raw material, limited references have been made to the more important. The subject is a vast one and has been studied by numerous workers for many years. Intensive research continues on the whole range of products which can be directly extracted and manufactured from the sugar-cane. Recent work on sucrose has disclosed new possibilities for the synthesis of chemicals which are useful in medicine and surgery and in industry. Under existing conditions the processing of by-products at the sugar factory, with the exception of molasses for the


production of rum to a limited extent is not attractive, while the present avenues for profitable disposal of bagasse and filter mud as raw materials are restricted. Molasses is the one in greatest demand, and the most widely useful under present conditions. To assist the planter it may be helpful to quote representa-t ive figures for the proportions of waste and by-products in terms of weight of cane. These vary considerably with cane variety, soil and weather conditions, and are affected by different factory processes and efficiencies.

Fibre is present to the extent of some 14% on cane equivalent to approximately 28% in terms of the wet bagasse as discharged from the last mill, containing nearly 50% of moisture. The amount consumed as fuel depends upon boiler efficiency, and the nature and extent of auxiliary services supplied with heat and power from the factory plant. Assuming that 80% is so used, the amount available for industrial use is 2.8% (dry) fibre, or 55 lb. per long ton of cane. The value at the sugar factory would probably be about is. depending on costs of preparation and transport to the processing plant.

Filter mud.—This material as separated by the Dorr-Oliver process amounts to about 2.5% on the weight of cane and con-tains + 78% of moisture. The dry matter is equivalent to 0.55 % of the cane. Assuming that 12% of crude wax, valued at 2s. per lb., is recoverable from it, the gross value of the wax per ton of cane is 3s. The net value of the cane for wax recovery purposes at present market quotations, allowing for costs of extraction would be about is. 6d. at the sugar factory.

Molasses.—The quantity produced per ton of cane varies con-siderably, as does the market price. The normal production of about 60 to 70 lb. per long ton of cane is worth as a raw material at the sugar factory about is. upwards, in accordance with de-mand, transport costs, and availability of markets.

The approximate figures quoted show that the raw material value of factory by-products may range upwards from about 3s. 6d. per long ton of cane, if they are in demand for secondary processing. The values cannot be accepted for general application, the object being to indicate their relative importance as additional factors in the overall economy of the cane sugar industry.


Sucrose in Relation to Industrial Expansion There can be no doubt that sucrose is by far the most valuable

product obtainable from sugar-cane from the point of view of financial returns on cane per acre planted and per ton milled. While the by-products and factory wastes may add a little to the value of the cane they are rarely worth the trouble of processing at the sugar factory itself, the only exceptions being rum and to a lesser extent industrial alcohol. Should the demand for sucrose at prices sufficiently attractive to planters and millers become completely satisfied, there are strong grounds for the conviction that research has demonstrated the extension of profitable indus-trial uses of the cane, of its direct product, sugar, and the factory by-products derived from it. Thus a higher proportion of fibre could be diverted to industrial use and the sugar in the cane might be utilized for food yeast, alcohol, or the manufacture of fine chemicals. The processing of the surplus cane to provide the raw materials would probably be simplified and conducted in accor-dance with the final products to be manufactured. For example the evaporation, sugar boiling and centrifugal stations would not be needed if the cane juice were to be used solely for food yeast or alcohol production.

Location of Secondary Manufactures The question arises why the useful and interesting range of

secondary products derivable from the sugar-cane does not receive greater attention from sugar manufacturers. So long as cane sugar continues in good demand at remunerative prices few sugar manufacturers are likely to embark upon a more extensive • campaign of by-products recovery and utilization in close association with their factories than they are now doing. Their main efforts now concentrated upon obtaining the highest possible efficiency in sugar recovery might to some extent be distracted by attention to processes such as the manufacture of fibre board conducted at the sugar factory. Primary attention would still be related to the processing and the extraction of sugar from the cane. Unless therefore separate self-contained units for each additional manufacturing activity were possible, a condition which implies a large scale undertaking with adequate throughput to


keep the auxiliary plants in full time operation with their own supervisory staff, it is more attractive either to sell the by-product, or to dispose of it in the simplest and least troublesome manner. In most places sugar factories are in operation for only a part of each year, and though during that period heat and power can usually be made available for auxiliary enterprises at comparatively low cost, the expense of such supplies at other times would be greatly increased. Power plants for sugar factories including steam boilers and electrical generating equipment are designed as integral units in balance with full-scale normal operation. Provision for continuing any but the usual out of crop services involves either the use of part of the sugar factory system or the installation of supplementary equipment, both of which are unsatisfactory. One exception to this is the association of rum and alcohol manu-facture from molasses with cane sugar extraction in parts of the West Indies and to a limited extent elsewhere, for which there are special reasons. It is more usual to process molasses at central distilleries quite separate from sugar factories, or to export the material for industrial use elsewhere.

Cane sugar manufacturers are fully alive to the possibilities of utilizing waste and by-products from the sugar-cane, and as has been seen scientific investigation has shown that an astonishing variety of useful substances can be prepared from them. As a general rule, however, the advantages are recognized of having the secondary manufactures conducted independently of the sugar factories, with certain exceptions. This preference for centralizing waste and by-product processing separately from the sugar factory is undoubtedly sound from considerations of industrial efficiency. A further barrier is introduced when it is necessary to use imported material to any considerable extent in the manu-facturing process, and this consideration becomes even more important when the new products command only a small local market or none at all. In highly industrialized countries the position is different as the raw materials, the special substances needed for their extraction or manufacture, and markets for their products are co-existent.

Having decided that waste or by-product utilization is a con-tinuing and profitable venture, the comparative advantages of conducting the work near to the cane areas or at some more

35° AGRICULTURE OF THE SUGAR-CANE

favourably situated centre must be considered. Except in Australia (Queensland and New South Wales), South Africa (Natal), the U.SA. (Florida and Louisiana), Hawaii, the South American Republics, and possibly Puerto Rico and Cuba, it appears more advantageous to export the raw materials as such if their value for manufacturing purposes covers transport costs and provides a satisfactory return. India presents a special case as a high pro-portion of the cane is processed by inefficient methods, and some considerable expansion of modern sugar extraction processes should precede any secondary manufactures using sugar-cane as the basic material, though progress in these directions may be expected. Bagasse and molasses are already sent to manufacturing centres from some of the cane sugar areas, but filter mud is a more difficult material to transport, though the possibility of concentra-ting the cane wax into a smaller bulk by a modification of the juice clarification process, or in some other manner seems worth investi-gating. The recovery of the wax at the sugar factory introduces considerable industrial hazards and is accompanied by other dis-advantages among which is the normally limited period of crop operations.

These matters do not directly fall within the scope of the planter, though he is concerned in any profitable method of disposal of his crop. The rising costs of production of cane and sugar are focusing interest on the extensive range of materials directly and indirectly obtainable from cane, some of which appear likely to increase in importance.

CHAPTER 20

RESEARCH AND THE PLANTER

Effects of Research The progress made by the industry has been accelerated by the

application of the results of research, conducted directly upon the problems of crop production, as well as on matters not intimately associated with cane sugar. The need for organized study of the sugar-cane, the soil in which it grows, its responses to different treatments, and indeed all matters relating to the crop has been recognized to an increasing extent during the past 50 years. The remarkable achievements of this work have enabled the industry to surmount grave hazards which have threatened cane crops, and to apply methods of husbandry which have brought about increased yields, improved economy, and protection of the soil. T h e genius of engineers and chemists has transformed extraction processes ; while investigations on by-products recovery, and industrial uses of sugar have discovered new outlets which give promise of great importance in the future. The planter's interest therefore does not cease when his cane is on its way to the mill, but his main concern is and must continue to be the already sufficient complexity of matters relating to successful and pro-fitable crop production.

The Planters' Interests in Research T h e subjects which are of close concern to the planter are those

related to the soil and the crop, each of which offers a range of intricate and inter-related problems for inquiry. The method of investigation of a particular matter is quite as important as the matter itself, and as knowledge of soils and plants has expanded, so have the methods of investigation become altered. This helps to explain why much of the work of early investigators on soil and plant interactions has had to be repeated by modern methods. But this is not the only reason for continued and increasing atten-tion to research. The materials dealt with are dynamic, not static. T h e soil to-day is regarded as a complex living organism, not in

351


the sense of a plant, animal, or other creature, but as a material partly of a mineral nature which supports innumerable living creatures, both beneficial and harmful, the whole being in a condition of constant change. The population, nature and life cycles of soil organisms and the changes in the soil components are influenced by the treatment given to the soil, and by the plants which grow in it. Successful agriculture depends upon securing a balance that will induce plant growth and maintain the soil in a state of fertility without impairing its ability to grow successful crops. The means of securing this balance must frequently be modified to cope with the constantly changing conditions in the soil and their effect on the plant; as well as by variation in the behaviour of the plant induced by pest, disease, climate, or the intervention of human agency, as for example in producing new types of cane, or by the treatment given to the soil.

The Relation of Earlier Work to Modern Needs Some of the results interpreted from earlier soil studies were

undoubtedly correct for soil and the plant as they then were. Thus it was found in many places that potash manures were in-effective upon yields of sugar-cane and sugar, the conclusion reached being that ample available supplies of potash were present in the soil. Examination of those soils many years later disclosed, serious potash deficiency, which in some instances affected the appearance of the plant and was recognizable by a discoloration of the leaves. What had happened was that the potash reserves in the soil had been used up at a greater rate than that at which they could be replaced by the ordinary dynamic changes occurring in the soil, so that potash fertilizer was necessary to secure normal plant growth.

Field Experiments The principal differences between the work of past investigators

and research as now conducted are in respect of method and inter-pretation of results. It is impossible to select two areas for com-parative field experiments, however small, in which the soils are exactly alike in every particular, and even if this could be done, there would be differences in the plants growing in the same area, as well as between those in the two areas. Moreover, various small

RESEARCH AND THE PLANTER 353

errors in weight, measurement and treatment unavoidably creep in. The effect of these differences upon results can be reduced to negligible proportions by carrying out each comparison several times, and interpreting the findings by statistical methods. Field experiments planned to study plant and soil interactions, plant behaviour in regard to different applications of fertilizer, the comparative yields of different varieties, and a range of related factors, are conducted in small plots of uniform size, with each experiment repeated several times. The plots within the total area devoted to the trials are chosen at random, and not personally selected by the investigator. Each block of plots is used to deter-mine the effects of two or more factors which affect plant growth, yield of sugar, and so on. The number of factors in each block should be limited to practicable proportions. Thus the effect of three types of fertilizer at one level of application compared with each other and with none at all, on one variety of cane, each experiment repeated three times would require 24 plots. The basic experiment would be to ascertain the response of the cane to nitrogen in the absence of phosphoric acid and potash, nitrogen and phosphoric acid without potash, all three together, phosphoric acid alone and with potash but no nitrogen, and so on, the number of comparisons being eight. The data ascertained would be the weight of cane, the weight of sucrose, and the character of the juice from each plot. This information would then be ex-amined by statistical methods and the results computed, with the probable error of each. Details of how this is done are possibly of little interest to the planter. He wants to know what treatment or combination of treatments will produce the most profitable crop. It should however, be appreciated that the old method of arriving at conclusions from such trials, before the application of modern statistical analysis to agricultural experiments, has been proved to give deceptive information. Thus, with three similarly treated plots in the experiment outlined, the true average yield of cane or sugar is not the arithmetic mean of the figures obtained from each plot. It is calculated by a method which assesses the extent of the probable errors of the experiment, and in the final result the figures will be used to show the comparative effect of the different treat-ments. The design of an experiment, the mode of conducting it, and the interpretation of the results are of equal importance.


They are matters for the scientific investigator. The practical planter who wishes to carry out field experiments on his land should only do so under the advice of someone trained and ex-perienced in the subject. Trials such as those in which the effect of a particular treatment and none whatever are tested on adjoining plots of the same area may give an indication of the better method, but are entirely useless for true comparisons, and indeed quite possibly will give a result directly contrary to the truth.

Research Organizations Recognition of these facts has caused many planters'

societies to establish their own research organizations for the investigation of the numerous and varied problems of crop pro-duction. Such work has long been conducted by public institu-tions, universities, and other educational bodies, but the need for more intensive and practical inquiries has greatly expanded research activity. There are now so many specialized branches dealing with the cane sugar industry that definite projects are entrusted to those best able to conduct them, and rarely if ever can a single institution accept responsibility for all of them. Further, there is a distinction between what is called fundamental research and applied research; and between long and short range investigations. Fundamental research is usually considered to be the pursuit of knowledge to increase man's understanding or knowledge for the sake of knowledge. The conduct of investiga-tions in which the objective is not defined in concrete terms often discloses information of vital importance from the practical and industrial points of view, and the applied research worker, engaged in the study of specific problems must keep himself informed of the progress of fundamental research. Long range work is related to fundamental research and is often synonymous with it. Both are best carried out in institutions of academic standing with adequate provision for the expense and equipment required.

The planter and his research schemes are concerned mainly with short range, applied research, or in other words, the visible problems related to the factors which influence successful crop production, its improvement and continuance. Attention should also be paid to similar questions which may arise in the future, so


that knowledge will be available to cope with them, or at least to provide a basis for any further work which may become necessary. The range of subjects needing attention will be evident from earlier chapters ; the extent of research activities needed to deal with them will be affected by local conditions ; while the provision actually made will depend upon the importance attached to the investigations needed, and the resources of the organization financing the project. Most ventures of this kind have been marked by small beginnings and a critical body of founders. Interference with established practice is often met by resentment and reluctant attempts at modifications suggested by the investi-gators. Very few successful efforts to apply the results of research are sufficient to generate enthusiasm, and before long the embryo scheme develops into an organization regarded as no less im-portant than the society which brought it into being.

The investigations pursued by various research institutions which have been established by the cane sugar industry include :—

(a) The breeding, study and distribution of new varieties of cane;

(b) the investigation of soils, their cultivation, drainage and management;

(c) plant nutrient deficiencies and their correction ; (d) pests and diseases, their effects and control; (e) weeds and their eradication ; (f) meteorological studies in relation to growth and maturity; (g) irrigation systems, and cycles; (h) planting methods; (i) mechanized methods for land preparation and cultivation.

These do not exhaust the projects directed to the study of crop production problems for sugar-cane, but are sufficient to em-phasize their extent and importance. Complementary to work of this description is the immense range of subjects related to the processing of the cane for the extraction of sugar which are also being investigated. The prosperity and security of the whole industry can only be assured by continued appreciation of the importance of research, combined with adequate financial sup-port for its prosecution on organized lines, and the application of its results to practice.


The Special Position of the Research Worker Apart from the more material aspects of research, in which the

planter is likely to be mainly interested because of their direct effect upon his own activities, the research worker himself and his relationships with those on whose behalf his studies are conducted must at all times be considered. Administrative and executive control of a research institution are different from those of a mill or factory. There is often a tendency to regard members of a research staff as paid operatives employed for a certain industrial job, rather than as students, thinkers, inquirers, and explorers of knowledge. This attitude can only lead to disappointments and dissatisfaction on both sides. Mutual confidence and respect are essential to success, and attempts to direct the methods of research workers must be avoided. The investigator should be afforded the greatest possible degree of freedom to pursue his inquiries in his own way, the only limits imposed being the projects for study and the financial provision made for the conduct of the work. The former should be defined in the widest terms, and the latter should be generous.

Administration of Research A common method of general control of research activities is

by a committee representative of the organization which provides the funds, and which is comprised of members on whose behalf the investigations are conducted. The old adage about the man who pays the piper can only be applied in the broadest possible sense if good value for those funds is to be obtained. Any scientist in charge of a research institution will agree that some control is necessary by an authorized body such as a research committee; it is the extent of that control, and the manner in which it is exercised that may lead to difficulty. The senior officer of the research staff, usually called the Director of Research, should himself be a member of the controlling body or committee by virtue of his office, with authority equivalent to that of other ordinary members. In this way the most important person in the whole scheme, upon whose position and responsibility the organi-zation depends for success, is enabled to understand fully the view point of the committee, and to enjoy their complete confidence in all matters. On his advice the broad outline of research projects


is decided, and money provided to conduct them. Such decisions are usually made after the committee has considered a scheme for the work of the institution and a carefully prepared budget of expenditure, both of which are prepared and submitted by the Director of Research. The " scheme " will include a general statement of the various lines of work proposed, some of which will be of a continuing nature—cane breeding for example—and others possibly limited to short though indefinite periods, such as an inquiry into the most economical densities of planting under varying conditions. The budget will normally be for one year, and will include provision for all staff, equipment, and other necessary expenses, under main heads. Staff appointments and salaries should be subject to the sole approval of the committee, and not varied without their consent. Other items of expenditure, including assistants of all grades, equipment and materials, travel-ling and transport, and general expenditure, should be under the control of the director within the approved provision for each item or group. In short the senior officer should be given full executive responsibility, with the general approval of the com-mittee, for the investigations to be conducted, the staff assigned to them, the expenditure for all purposes connected with them, and the whole conduct of the affairs of the organization in his charge. The committee would then be completely free, as it should be, of any concern with details, though information on any aspect of the work could be supplied by the Director of Research. A system which has the merits of simplicity and effectiveness is the regular preparation of comparative financial statements and brief progress reports on work for the information of the committee. These should be not less frequent than quarterly, though monthly statements of account may prove more useful. The progress reports can be short, informative accounts, free from much detail, giving in broad outline the nature of the various investigations and referring to any matters of outstanding interest. Such reports should not be confused with those which describe in detail the specific subjects and results of investigation with recommendations and advice, for the information of planters, though it is helpful to send them copies so that they may be kept in the closest touch with the work of the committee and of their research institution.


Private Research Organizations In many instances, large plantation organizations include a

research division for the study of specific problems encountered in their own operations, and thus supplement the work of the establishment set up by the association of which they are members. It is obviously desirable that there should be close co-operation and free interchange of information between the two. Still other companies which are the only ones engaged in cane sugar produc-tion in their areas, maintain research staffs which in the circum-stances have to be so organized as to deal with all subjects needing investigation. Their contacts with other institutions are effected by attendance at regional conferences, by the interchange of visits, and published reports. Examples of the former are to be found in the West Indies, and of the latter in the Dominican Republic and Florida.

Facilities Essential to Research The facilities necessary to enable research workers to conduct

their investigations include an extent of land which is representa-tive of the area in which sugar-cane is commercially grown, and laboratories for various aspects of detailed study (Fig. 54). A library, and an office to deal with accounts, correspondence, and records are essential auxiliaries. The experimental station is in effect the central part, but not the complete whole of the research organization. The object of the various studies undertaken is to assist the planter in various ways, which implies investigations, trials, and a careful examination of their results, under conditions which are in all respects comparable with those encountered in the commercial production of the crop. However carefully the land may be chosen, the central station cannot include every condition found in the sugar-cane areas it is designed to serve, so that provision must be made for work to be carried out on planters' land. Similar circumstances apply to large estates such as those mentioned. While therefore field experimental work is a necessary part of the studies conducted at the research station itself, it must be supplemented by properly designed investigations in the cane fields under the control of the same workers. Indeed it may be found that sections of the research programme, such as fertilizer investigations are best pursued in that manner, which is an im-

FIG. 56.—Oblique photograph of a sugar plantation in Jamaica.

[Courtesy of Hunting Aerosurveys Ltd.

FIG. 57.—Two-row cutter-planter with fertilizer attachment.

[Photos by courtesy of (Colonial Sugar Refining (.lo. Ltd., Sydney, Australia

Fro 58.—Cultivating young cane, Hambledon, Queensland.


portant step in the translation of the results of inquiries to com-mercial practice. Applied research such as that carried out on the problems of sugar-cane agriculture is a two-way affair, calling for the closest co-operation and understanding between the scientist and the planter. This important relationship which is a primary factor in the success of a research institution is strengthened by field experimental work carried out in the cane fields under the control of the research worker with the help of the plantation staff. It develops into a valuable extension service which engenders respect and understanding, and what is perhaps more important, causes both parties to realize their mutual dependence. Thus the planter derives benefit from the personal contact on his own ground with the research worker, while the knowledge of practical problems in the field gained by the latter helps in his investigatory work.

Reports, Their Compilation and Distribution The results of the various lines of inquiry are compiled and

brought to the attention of those interested in the form of reports, special articles in journals, and by meetings of planters and re-search staff. Information of general interest is sent to all con-cerned, and that of local or individual importance to those parti-cularly affected. Although the issue of a regularly published journal provides a most valuable medium for bringing these matters to notice and enables them to be recorded in a permanent form, this method alone does not satisfy requirements. In many cases the delay between the compilation of the original statement and its issue in printed form reduces its practical utility. At the same time, the preparation of a report for printing and wide circulation involves more detail and very often a different manner of presentation of the same data than would be used for a direct report in multigraphed form, or a personally communicated state-ment at a meeting. In practice all three methods are normally used, the two latter more particularly for progress reports on research projects and for the immediate circulation of important information, which may later be published in suitable form for permanent record.

The mode of compiling statements of the results of scientific investigations and recommendations based on them, for the use of

AA


planters, has much to do with their usefulness from the practical viewpoint. Basic requirements are conciseness and simplicity. Scientific terms not generally understood should be avoided unless they are essential to the subject, when they should be defined. Intricate mathematical formulae, calculations except of the simplest nature, botanical names unaccompanied by local and well-known ones for the same plants, with all matters of a similar nature should be excluded. A short statement of the nature of the problem, an outline of the method of study, a brief description of the results, and a concise explicit recommendation regarding the procedure the planter should follow provide all that is necessary.

More extensive reports for publications would include matter expressed in what is commonly called "scientific" language, and some would of necessity be compiled in a manner more suitable to study and discussion by scientists. These are essential to the conduct and progress of research ; they are prepared for a special body of readers and have their particular field of circulation. The planter invariably displays great interest in such expositions, which is increased when he has already received the reports on the same subjects prepared for his personal information.

In addition to special communications on research projects it is helpful to circulate other news items of interest which come under the notice of the research organization in the course of its normal work. Such matters include meteorological data ; outbreaks of pests and diseases ; unusual behaviour of crop plants ; effects of using new or improved methods in the field ; useful extracts from literature and reports from other countries ; the performance of agricultural equipment; and a wide range of subjects related to sugar-cane. Similar procedure is most helpful on the large planta-tions which have their own research organization. To sum up, the pursuit of knowledge can only be useful if it is accompanied by effective means of conveying the information derived from it to those who need it.

The Value of Handbooks In the course of time new and improved methods resulting from

research become standard practice, and though this is subject to modifications arising from new knowledge, it is often convenient to compile a handbook which includes the basic principles of


agricultural operations applicable to the territory for which it is planned, and proved methods of working, with general informa-tion useful to the planter. Sugar-cane agriculture as practised now requires a working acquaintance with an extensive range of sub-jects and the practical ability to apply such knowledge. The utility of an authoritative work which presents the miscellaneous data needed from time to time by the plantation operative in a readily understood manner is beyond question. An excellent example is the Queensland Canegrowers' Handbook. Modern methods of loose-leaf binding could well be used in the prepara-tion of such compilations designed for conditions in other places, so that special additions issued from time to time by the local research institute could be included and the whole work thus kept up to date.

CHAPTER 21

PLANTERS' ORGANIZATIONS

Origin and Development of Planters' Organizations The establishment of associations of groups with common

interests in various agricultural industries, including sugar, is a modern development which has largely been brought about by difficulties in the profitable disposal of produce by individuals and the need for unified representation and action in respect of numerous matters of general interest. The impact of the 1914—18 World War was severe and its effect on the cane sugar industry was profound. World prices of sugar soared to levels which had been unknown since the Napoleonic wars of more than a century earlier, but this temporary prosperity was rapidly suc-ceeded by a decline which soon developed into a depression. During this period manufacturers or millers of sugar in many countries realized the necessity for group action, and planters were not slow to follow. Matters of common interest to growers of sugar-cane, and manufacturers of sugar in cane sugar pro-ducing countries, to-day are dealt with by associations. Indivi-dual members, while free to express their views within their association, are bound by the decisions of the body of members Unified action in this way has the greatest possible force and effect on behalf of the industry thus represented. Originally established with limited objects which at the time of their forma-tion appeared to be of first importance as well as likely to com-mand,the support of most, if not all, of their membership, these associations have increased in strength, scope and significance. Many of them are corporate bodies ; some are legally constituted under the laws of the territory in which they operate; while others remain as voluntary associations.

The International Sugar Agreement of 1937, which was given legal force in British Commonwealth sugar territories by local enactments, did much to strengthen the positions of associations within the cane sugar industry, and to expand their activities. The bulk purchase of sugar by the British Ministry of Food from

362

PLANTERS' ORGANIZATIONS 363

the British Commonwealth, commenced in 1940, and now to be continued until 1960 has further enhanced the already great importance of associations of cane sugar producers. In the British West Indies the need for united action in major matters, parti-cularly those concerning the disposal of the export sugar crops of that area, brought about the formation of the British West Indies Sugar Association in 1942, with a membership comprising all the individual territorial sugar associations of the British Caribbean countries, including British Guiana. This association is a legal entity incorporated under the laws of Trinidad. The eight member associations are societies of owners of sugar mills and sugar-cane estates, so that they are not solely planters' groups, though the interests of cane growers as such are prominent in their activities.

Types and Functions of Associations There are several types of sugar-cane planters' or growers'

associations. In the British West Indies, such bodies are of two kinds—those comprising owners of sugar-cane plantations and factories ; and those composed of growers only who sell their cane to factories. Natal, South Africa, has three—the sugar manufac-turer-estate owner, called the miller-cum-planter, the European growers who form a group of large planters, and the non-European growers, who correspond to a part of the membership of the cane farmers' association of Jamaica. In Australia the whole of the cane is grown by farmers who are all members of a growers' association, with local associations, the members of each of which supply to one mill. The form, constitution, and activities of all these are largely governed by purely local considerations, though there is the underlying common purpose—the protection and develop-ment of their interests in the sugar industry. These objectives ultimately depend upon the market for sugar, its extent, value and prospects, factors which not only affect the prosperity of the millers or manufacturers, but the fortunes of planters and growers of all classes.

The whole industry should therefore ideally operate as a co-ordinated unit with its component parts in a state of adjustment so that the degree of freedom of any one of them is controlled by the efficient working of all. Failure fully to recognize the complete inter-dependence of all parts of the industry can lead only to


avoidable difficulty which may amount to disaster. Each section is entitled to its share in the prosperity of the whole in proportion to the capital invested, the effort expended, the risks taken, and the efficiency with which its operations are conducted. All should strive to attain the highest standard possible in the various phases of work, for although there is and has been a closer control of markets than ever before, there is still a competitive element amongst suppliers to those markets, and wide variations in productive efficiency which are reflected in the actual cost of sugar. These variations are related to differences in conditions, such as soil, and climate, over which the planter has little or no control, and to the internal economic and social situation in the country of production.

Unbalanced Position in Some Countries There is in some cane sugar countries a visible tendency to get

out of balance with the general trend of costs and standards, thereby creating an artificially prosperous position for cane sugar, more apparent than real, which must be corrected if a tragic collapse is to be avoided. Evidences of this are readily discernible in the British West Indies. From a position characterized by low market prices, sub-standard wages and living conditions for labour and correspondingly poor returns to manufacturers and independent growers who sold cane to factories, the combined effect of war controls, improved and increasing prices, and the mounting costs of labour have brought the industry in most of those countries to a precarious peak of costs and prices, from which a careful descent must be made to safer levels if they are to retain a satisfactory position in overseas markets. The remarkable expansion in production during recent years has been accompanied by disproportionate increases in cane prices and in the wages paid to certain classes of worker. The former have been influenced by the method of assessment of prices paid for fanners' cane in relation to the price of sugar, while the latter has occurred by the effect of percentage increases in rates of wages paid more than 10 years ago for many types of work which have been superseded by improved methods or totally replaced by new ones. A result of this has been that the advance in efficiency has not been accompanied by a corresponding improvement in the financial position of sugar


manufacturers and planters, too great a share of the increased prosperity having gone to others because of the faulty basis of distribution. The safeguard for the present is the production of the greater proportion of the cane by estates directly attached to and operated by the organizations which own and work the factories. Their adoption of improved methods which have brought about bigger yields, and more economical working, have cushioned the effects described and placed the miller-cum-planter, or as they are called in the British West Indies, the estate owners, in a strong position to meet the internal economic difficulties associated with the instability of labour rates and prices for purchased cane. The situation is affected by the high cost of foodstuffs, both locally produced and imported, and of the other basic necessities few of which are of local origin. Indeed the sugar industry is a victim of circumstances over which it can exercise little control, but which it can and should influence by constructive action through planters' organizations. It is significant that local prices of sugar in Australia and South Africa are much lower than export prices paid by the British Ministry of Food for Commonwealth sugar, despite the facts that domestic consumption absorbs by far the greater proportion of the output, and the average market value is therefore much nearer to the local market price than it is in Jamaica for example. Standards of living in the former two countries are much higher than in the West Indies, and on the evidence available those engaged in the sugar industry are comparatively far more contented and prosperous.

Dangers of Inequality of Interests The unbalance of cane sugar affairs in parts of the British West

Indies may be to some extent related to the local policy of the planters' associations, and to their integration with the industry as a whole. In contrast to Natal, for example, the cane farmers' association in Jamaica is constituted by law to include all persons who grow sugar-cane for sale to a factory. Though district branches have been formed, the operative body is the managing committee of the whole association, which conducts negotiations with the sugar manufacturers' association principally in connection with the mode of calculation of prices for members' cane. Both of these groups are represented on the Sugar Industry


Control Board, a statutory body which allocates to factories quotas for export and local market sugar, deals with disputes between farmers and millers, keeps a register of farmers, and generally regulates the internal affairs of the industry with the exception of wages. This controlling authority, however, can exercise but little influence on the cane farmers'' association in regard to economic relations with sugar manufacturers, and though the law provides for an official and enforceable method of fixing prices to be paid for cane, these are settled by negotiation between the farmers' and the manufacturers' representative bodies, with the labour unions watching to see what advantage they can obtain for their members.

Qualifications for Membership While in principle a single association, whose members are all

engaged in the same pursuit but to differing degrees, appears ideal, it will not always stand the test of practical utility, and instead of being truly democratic may be subject to the autocratic domination of a very small but intensely active minority, whose purely selfish interests direct decisions supposedly approved by the whole body. A situation whereby a small group of members produces a high proportion of the total cane, with large numbers responsible for the rest, all having equal standing and voting power, in the affairs of a single association is certain sooner or later to result in a serious conflict of views and a weakening of the status of the society. The interests of a supplier of 10,000 tons of cane each crop are remarkably different from one whose total delivery does not exceed 20 tons, or to put the matter in another way, the large planter should be able to negotiate in company with his fellows of similar output, and the small growers or peasant cultivators should be combined in a separate association. Experience has demonstrated conclusively that such separate institutions for distinct classes of growers sacrifice nothing of their effectiveness but rather gain strength because of the closer interest of their members. The number of members comprising an association of this type means very little unless it can be shown that their individual responsibilities and standing are similar in degree as well as description. The principles of democracy lose much of their force and effect if too much reliance is placed on the mere forma-


tion or existence of a society than upon its constitution and the qualification for membership. The establishment of more than one organization for growers of a single commodity makes it much easier to deal with the special interests of each well-defined group, as well as those which are common to all. An example will make this clear. A proposal to impose a duty upon fuel oil used for agricultural purposes would be most unlikely to affect the 20-ton cane grower, while it would be of vital import to the large planter. Representations from an association of 10,000 members, of whom 90% were non-consumers or only very small users of oil, would carry less weight than those from a separate association comprising 1,000 substantial consumers.

There is no intention of advocating that planters' associations should be formed of arithmetically graded groups in quantitative scales of production. The object is to emphasize the desirability of definite qualifications for membership in accordance with standards which are described in the constitutions of distinct groups. When unified action becomes necessary regarding matters in which all groups are concerned, they would act in concert after reaching decisions on an agreed policy. The criticisms which have been advanced disclose what appears to be a weakness in a particular form of association. They are constructive in that they indicate one way in which improvement may be effected.

Objects and Methods Planters' associations have undergone progressive changes since

they were first formed. Such movements are characteristic of active bodies of persons having similar interests. While foundation principles remain unchanged, the scope of operations has expanded and methods have been modified to meet the ever-changing conditions of industry. To be successful they must be constituted in such a manner as to provide for attention to all important aspects of production and marketing on behalf of their members; to submit well supported and forceful representations when necessary to authorities and to other societies ; to conduct inquiries; issue reports; organize advisory services; carry out research; arrange supplies of materials ; appoint staff; borrow and lend money on security ; and make levies to defray expenses. Disadvantages of great numbers have been mentioned, but large


membership will not be a handicap provided there is sub-division into smaller units of convenient size. These usually take the form of district branches of the society, and include members resident or having their holdings in a limited area, so that they are known to one another, and have similar interests. In this manner, affairs which particularly concern individual branches, but which are of no great moment to the association as a whole, can most easily be dealt with, leaving the central body free to attend to important issues on behalf of the entire association. Each branch is constituted within the society, with objects consistent in every way with those of the main body, and having its own officers. The governing body of the central association should then be formed by the appointment of members selected by the branches to secure a fully representative management.

Legal Recognition A planters' association, while formed originally as a voluntary

organization, should become a legal entity if it is effectively to serve its members. If this step is not taken individual members and officers may be held personally liable for claims against them for " acts done or not done " which adversely affect the interests of any member. The decisions of the governing body or managing committee have no force or effect except through the willing acquiescence of members. Contracts on behalf of the society as a whole cannot be entered into, nor can voluntary agreements be legally enforced. The laws of different countries vary in the provisions made for the recognition of societies of this type, and the disadvantages described of a purely voluntary association are those which exist in most Commonwealth territories. Methods of securing legal status include statutory constitution, incorporation under company law, and registration as a co-operative society.

Reference has been made to the powers which an association should be authorized to exercise. While these should include all matters which can be foreseen at the time of formation, however remote the possibilities of needing all of them may appear to be, it is not incumbent upon the managing body of the society to give effect to every one of them. It is a simple matter to devise an original all-embracing constitution, but alterations are troublesome. In practice it is usually found that activities are limited to a


few points of immediate and important general interest, and that the scope of the work expands to other matters as time passes.

Duties of Members The existence of an active association does not entirely remove

from members their personal responsibility for watchfulness over their own interests, particularly those which influence the efficiency and success of their own work. While those in business on a comparatively large scale, with correspondingly high capital commitments and heavy responsibilities rarely neglect these matters, many with smaller interests place too much reliance on the ability of their association to compensate them for neglect. The failure of a planter to conduct his own affairs on lines which will ensure success reacts not only upon himself, but on the society of which he is a member. Much of the work of a planters' association concerns the marketing of produce, and the scale of prices paid for it by the purchaser, who is just as likely to be a member of another association with its own interests to protect. Negotiations between such bodies depend greatly upon the standard of efficiency of the members of both. Thus in his dealings with the sugar manufacturer, the planter expects that the cane he sells will be processed to the best advantage so that the price paid to him may be the highest possible. He will resent a depression in value of his cane because of some neglect by the mill to secure the highest recovery. His primary interest is certainly the return he gets for what he supplies, but in this concern he is indirectly a critic of mill efficiency.

On the other hand the purchaser of cane is not prepared to subsidize inefficiency on the part of the grower, nor is it reasonable to expect him to do so. The whole matter turns on the market value of sugar, upon which the value of the cane is assessed by methods which vary in different countries. The profits of the planter depend upon the material yields he can obtain from his land for effort and money expended on it. The miller or manufacturer cannot be expected to pay high rates because of misapplied effort, incorrect methods of crop production, waste of money, and inattention to his own affairs by the planter. The foundation of the business relations between sugar manufacturers and planters is mutual respect and confidence which cannot exist

3 7 ° AGRICULTURE OF THE SUGAR-CANE

in the presence of inefficiency on the part of either. When both activities are represented by the same people in one association, as for example, in sugar manufacturers' associations in the Caribbean area, and the independent planters or growers alone in another, the latter are or should be able to follow the agricultural methods of the organization to which they sell their cane with advantage to their own production. The remarkable advances made by the manufacturer-planter in both field and factory during recent years are due in great measure to the establishment of associations, primarily formed for purely business reasons, which have expanded their interests to include the study and application of improvements in all branches of their work. Planters' societies in many instances have progressed in similar fashion.

Increasing Usefulness of Associations The world position in regard to sugar to-day requires the

existence of soundly constituted responsible and active organizations throughout the industry in all countries where it is produced on any considerable scale. The international importance of sugar is now greater than during any previous period, and the indications are that this situation will continue. With sugar-cane representing more than two-thirds of the total world production of raw material from which sucrose is extracted, and amounting to about 200 million tons reaped and processed each year, no argument is necessary to support the view that sugar-cane planters' associations must play a vital part in the general affairs of a vast industry. The time may well come if indeed it has not already arrived, when some form of international organization of sugarcane planters is desirable. There are still great opportunities for the increased usefulness of local associations to their members, to the sugar industry of their country, and to its Government. The interchange of knowledge through the medium of an international association would prove of the highest material value, while the closer understanding brought about between peoples with a common interest would be a great factor in the development of harmonious relations between nations. This important result of successful plans for regional conferences within the cane sugar industry has been realized in small degree by the annual meetings of sugar technologists in the British West Indies.


Invited guests to these conferences include representatives from Hawaii, Florida, Cuba, the Dominican Republic, Puerto Rico, Martinique and Guadeloupe, the member territories being the British countries of the Caribbean. Though these conferences are not confined to planters' affairs alone, their international character is noteworthy, while their effect on the advancement of knowledge and practice in the cane sugar industry has been profound. It was truly remarked at one of these gatherings that it was so easy to bring countries together in the interests of science, and apparently so difficult to secure international accord in other human relationships.

Special Needs of Small Growers

In the discussion on the membership composition of a growers' association, the point was made that effectiveness can be sacrificed at the expense of purely numerical membership. Intimate connection with what are termed cane farmers in both hemispheres, combined with close study of the units of different types of association has brought conviction that small growers require a quite different form of society from that which is suited to the large planter. The fact must be faced that the peasant cultivator in many places, by whatever name he may be called, does not generally practise good sugar-cane farming methods when left to himself. Direction and supervision have brought remarkable improvement in districts when small growers of this type have been provided with instruction and advice, with which has been combined effective economic control.

Small Farmers in Fiji—

The tenant cane farmer system In Fiji, originally established to overcome the serious difficulties of large estate operation with indentured East Indian labour, has demonstrated that small farmers can succeed. In its original form, the scheme provided former estate labourers with land which they could work as individuals, assisted by their families, without paid labour. The farms of about 10 acres each in extent were subdivisions of the former estates, most of which were leased from the Government of Fiji. The mode of farming was devised by the Colonial Sugar


Refining Company of Australia, under whose control were the mills to which the cane was supplied. Each farm was provided with a cottage for the tenant and his family, outbuildings, and implements. The cropping area was divided into four parts, the crop cycle being plant, one ratoon, green manure. In this way a holding provided cane for the mill from one half of its cultivated area each year. Ploughs were loaned by the Company, and fertilizer was supplied, the cost of these services together with the rent being paid by deductions from the value of the cane delivered to the mill. The tenant farmers were told when to cut their cane, and co-operative reaping was organized so that no paid labour was employed at harvest. The price of cane was calculated by a formula which took into account the realized price of raw sugar and the quality of the cane in terms of recoverable sugar. Annual competitions were organized for each area, and prizes awarded for various aspects of good farming. The staff of the company supervised the work of the tenants, providing advisory and instructional services. While assistance was afforded by such things as the loans of ploughs, the supply of seed and fertilizers—that is, material help —no money was lent, and tenants were actively discouraged from borrowing. The holdings were solely devoted to the growing of sugar-cane by the approved system. Its success depended upon close supervision, and the sole control of the sugar industry by one organization.

Since first established some 30 years ago, the operation and control has undergone modifications, and there have been difficulties through dissatisfaction with prices paid, and objection to the strict rules of the Company. The labour movements among the more primitive peoples extended to the tenant cane farmer system in Fiji, which was also affected by political activities originating among the Asiatics settled there. The basic fact remains, however, that the scheme provided for a form of benevolent control combined with a system of agriculture suited to the people, the land, and the crop, which together brought security and relative prosperity to those who were previously employed as estate labourers. The essential aspect of the scheme was the use of the land in a manner which by actual experience assured good crops and the maintenance of fertility.


—and in Jamaica Cane " farming " by peasants in Jamaica, including people of

African and Asiatic origin, carried on without supervision, instruction or organization, displays remarkable differences from the Fiji system. A survey of some hundreds of holdings in one district disclosed that the average yield for registered farmers delivering small quantities of cane to a factory was under 5 tons of cane per acre. Their field work was gravely defective, and the land they worked showed evidence of rapid and serious deterioration. Cursory inspection of other areas revealed similar conditions. The people concerned, numbering several thousands of the small cane-grower class, need help, instruction, and encouragement to adopt safe and profitable methods of cultivation. The point emphasized here, however, is the futility of drafting them into the one statutory cane farmers' association along with capable and efficient planters whose methods and yields compare favourably with the best. Apart from the danger to the land which is cropped by inefficient methods, the position is created whereby demands are made for prices to be paid for cane which are excessive and uneconomic, because of the failure to produce profitable crops. The position has arisen from two main causes, the decline of other crops, particularly bananas which were formerly grown, and the increased prices paid for sugar-cane by milling companies brought about by the rise in the value of sugar.

The Organization of Small Growers The remedy is to develop a system of sugar-cane growing on

small holdings which will ensure economic yields combined with relatively good financial returns, and safeguard the growers' interest in the soil. Such a system should include the establishment of small societies of growers, each being confined to a limited area, with provision for instruction in agricultural methods, and organized supplies of the materials required. Encouragement should be given to co-operative working in regard to operations such as land preparation, reaping, and transport, with a view to reducing their cost. Group ownership of implements and other farm equipment might be developed. Definite standards should be decided upon for the conduct of the work by each member ;


and recognition as a cane " farmer " should be conditional upon the observance of rules and methods adopted for the group. These small societies or groups should be combined into district associations which would form the branches of a central body representative of the whole. Qualifications for membership of a local group should, amongst other matters, require cane growing by approved methods to be conducted by the member on a holding of not less than a specified minimum area, nor greater than a fixed maximum. In the event of a member ceasing to cultivate the minimum area of land, he should no longer be regarded as a " farmer " and his membership should be terminated. If the area cropped exceeded the maximum, the farmer should be qualified for membership of a separate association of larger planters.

Group Delivery to the Factory The difficulties of the manufacturer or milling company are

considerable when very small quantities of cane are supplied by large numbers of growers. The system proposed should include provision for group delivery of cane, so that the purchaser would transact business with a single representative of a number of growers, who in turn would organize the cane delivery from members of his group, and distribute the proceeds to them. The cost of separate weighing, accounting, recording, and payment for very small amounts of cane, often not greater than a few hundredweights, is disproportionately high. Frequent disputes occur with growers of this class and were it not for the legal obligation to register them as suppliers, and to accept their cane for processing, some manufacturers would insist on group deliveries, failing which they would decline to accept the cane.

The Position of the Small Grower It may be argued that the bounds of discussion of planters'

association have been exceeded; that the small cultivators referred to are not " planters," or even " farmers " ; that their production is negligible and without practical effect on total sugar production; and in short they are not an economic consideration. These views would find little support to-day in the cane sugar producing countries where such conditions exist. The present tendency is an increase in the numbers and production of growers

CHAPTER 22

THE OUTLOOK

Progressive Development The trends of the past half-century may be taken as some indica

tion of likely developments in the future. The expansion of production which has attended the progressive changes and improvements brought about by the application of new methods, the use of mechanical power, and the effects of cane breeding, has been accompanied by increased demand for sugar, and the dismal forebodings of the 1930's which led to the International Sugar Agreement of 1937 have been replaced by the brighter picture of a producers' market. The cane planter and sugar manufacturer alike are vitally concerned in whatever assurances can be given in regard to the future.

Extensive Investments The nature and extent of the planter's capital investments have

altered remarkably in most sugar-cane countries. Immense sums have been expended in irrigation works, drainage and other civil engineering projects of a major nature. Mechanization has involved the acquisition of expensive machinery, both power units and implements, with the provision of engineering services to maintain and repair them. Health and welfare srvices, with their hospitals, clubs, playing fields, staff and labour housing, have in the more recent past still further increased the capital outlay. The modern sugar factory is a vast integration of costly equipment, most of which is useless for any purpose other than the extraction of sugar from cane. If research can be considered a capital investment, then the amount is further increased ; in any event the devoted efforts of a large body of scientific workers who contribute so greatly to the progress of the industry must be included in even the barest outline of human and material investment in a vast world industry.

Apart from these conditions there are the interests of the great body of trained men in all branches of the industry whose knowledge, experience and skill direct and control the intricate organized

376

THE OUTLOOK 377

operations, which though so extensive in variety, must be carefully related to one another. The workpeople too, both skilled and unskilled, form an important part of. the whole picture, though the latter continue to decrease in numbers.

Confidence, Protection and Control These features taken together show the high confidence in the

future prospects of the cane sugar industry on the part of those engaged in it, and while contemplating his own part in the whole venture, the planter may be further assured by the continuing additions, extensions and improvements to the installations and services through which the disposal of the sugar and other products of the cane he grows takes place. Further to this are the various national and international trade policies which safeguard internal and export markets to a greater extent than ever, and extend protection as well as control to the planter.

The outlook for the immediate future is bright. Consumption of sugar is likely to increase still further, while the prospects of disposing of any surpluses which may occur later are becoming increasingly good. There is, however, no sound reason for complacency. Though the production cost of cane sugar is lower than that of beet sugar, the margin tends to decrease and the advantageous position of the former is further affected by the high costs of transport to markets which in many cases are overseas. The industry in certain countries was gravely affected by the 1939-45 World War. Some of those countries, notably the Philippines and Taiwan (Formosa) are back to pre-war levels of production. Formerly an importer of cane sugar, India appears to be a prospective exporter though that stage may not be reached for some years.

Men, Animals and Machines The higher standards of living and greatly enhanced prices for

food and other essentials have brought about increased wages for operatives and workpeople, while in many countries the attractions of other forms of work have depleted the labour force available for field operations in the cane sugar industry, and thus provided further stimulus to mechanization. These features are shared with other types of farming, in which the skill of the manual

BB*


worker on the land, formerly the basis of crop operations, has been replaced by that of mechanics and operators of machines and implements designed, constructed and tested by engineers who are in these modern days the power behind agriculture in more senses than one. The great reduction in the use of manpower for preparation and cultivation operations, and the decline amounting in some instances to the complete disappearance of animals for cane farm work is likely further to spread in places where the working population has alternative occupations, and where workers are not largely in excess of the total demand for labour. India and Barbados, which so greatly contrast in size, are both places where manual work will long be continued ; in the former for practically all tasks on the land, and in the latter for harvesting. Animal power is a feature of the former, but has largely given place to machines in the latter. Hawaii and Queensland are examples of high degree mechanization through shortage of manpower for the sugar-cane industry. Each area offers its individual problems, and little generalization is justified, though it may be confidently stated that with few exceptions the trends are in the same direction throughout the cane sugar producing countries of the world. (Figs. 57, 58.)

It will be clear from the foregoing pages that mechanization of all field operations is possible even in land subject to heavy rainfall, provided that ample power is available to carry on heavy work during dry periods. The only exception in certain areas is the reaping of the cane, though this is already conducted mechanically in Queensland, Hawaii, Louisiana and, to a lesser extent, in other places. New machines and improvements to older types are under constant study. The practice of mechanical reaping is likely to increase even in places where hand labour is still available, not because machines are cheaper to operate, but because they are more reliable than the labour forces in many places to-day.

Aircraft in Sugar-Cane Agriculture The use of aircraft, both of the rotating and fixed wing types,

has come into prominance during recent years for numerous kinds of agricultural work on an extensive scale in connection with the production of sugar-cane. Further expansion is likely to occur in the practice of such methods for operations for which existing

THE OUTLOOK 379

machines have proved themselves satisfactory, as well as for certain specialized work now carried out with ground machines. This indeed promises to be one of the outstanding developments of the immediate future, and to emphasize the point the following summary of operations successfully performed by aircraft is given :

(a) Photographic surveys. (b) The application of weedicidal dusts and sprays. (c) The sowing of leguminous cover crops. (d) The application of fertilizer. (e) Control of insect pests. (/) Distribution of rat poison. (g) Field inspection and control.

The use of aircraft for these operations offers the important advantages of high speed, and avoidance of damage to soil tilth by the movement of men, animals and machines. Under favourable conditions there now appears no need for any movement to take place on the surface of the land after the cane has been planted until it is harvested, unless irrigation is practised. (Fig. 59.)

Fertilizing and Irrigation Recent studies in fertilizers and their application indicate that

there is little or no advantage in distributing the fertilizer in more than a single dose, or in applying it to the plant crop at any time after the actual planting of the cane. The rapidity with which anhydrous and liquid ammonia have come into favour is a clear indication that where ammonia compares favourably in price with other forms of fixed nitrogen it may be used to a greatly increased extent.

Economies in the effective use of irrigation water are the subject of continuing study by research workers and plantation staff. This, with other cane production problems, is affected by the mounting cost of materials, machinery and manpower. Despite the high capital outlay for permanent overhead irrigation installations, the great advantages of this method are likely to bring about its extended use, more particularly where the water is expensive and not in abundant supply. Apart from the actual watering of cane greater use is likely to be made of such water for the application of dissolved fertilizers, soil improver materials, and possibly herbicides.


Scientific Methods The intensive studies being pursued in so many places of all

aspects of sugar-cane agriculture are bringing about scientific methods of crop control, which themselves are capable of further improvement and more extensive application. Combined with methods which reduce and cheapen preparation operations, and with newer methods which have become available through the conquest of the air and the production of a wide range of chemical substances which assist the planter in the control of pests and diseases including weeds, these are likely to lead to further increases in crop yields. The possibility of extended ratooning in many areas, where soil tilth can be maintained under conditions which limit the amount of movement on the surface of the land, also suggests itself. New approaches to the work of cane breeding and the greater knowledge of the factors which influence the type of progeny produced, which are beginning to come forward from the genetical researches of various workers will further contribute to progress.

All this, however, will not be fully effective unless the planter himself conducts his farm operations correctly, and avoids to the greatest possible extent losses of time and material at all stages. The term " material " is used in its widest possible sense, and includes everything related to the soil, the crop which grows in it, the men who control, conduct and execute the various types of work, the mechanical devices of all descriptions found on the farm, and the water which is applied to the plant, naturally or artificially by rainfall and irrigation.

Disposal of Sugar Competition in export markets, at present limited under quotas

and trade agreements, may become a renewed feature. Those countries which enjoy a high and increasing local consumption are better able to meet such circumstances, but limits will continue to be imposed on internal sugar prices by considerations related to the general cost of living and the production of manufactured goods. The increases in population while expanding the markets for sugar, will stimulate the better use of land for cropping and lead to more intensive methods for the production of sugar and

THE OUTLOOK 38l

food crops as is already occurring in India. Sugar is likely to make an increasing contribution to world requirements of protein foods rich in vitamins of types similar to food yeast but more widely useful.

The Biological Balance in Relation to New Methods The changes in the biological balance—that delicate adjustment

of natural conditions—brought about by the use of new chemical substances for the control, suppression, and eradication of the enemies of the sugar-cane, and for the stimulation of growth, require constant study. Assurances based on observations made of the degree of persistence of the complex organic compounds used have dispelled fears that permanent adverse effects upon soils and the plant growth they support may occur. There is the possibility of the complete disappearance of some objectionable plants in areas where continued weedicidal measures are taken, accompanied by the risk of their place being taken by others offering similar problems of control.

Conclusion The planter to-day enjoys advantages which have developed by

the advance of scientific knowledge and its application to the problems of crop production to a truly remarkable extent, together with those derived from local and international industrial and market controls. All engaged in the industry from the small cultivator to the large estate operator are able to obtain expert technical advice on their varied problems. The help and protection accorded in so many ways has relieved the planter from the grave anxieties which were his constant companions in the recent past, and have given him great opportunities for advancing his own interests. The effects will become increasingly apparent in the future.

TABLES AND MISCELLANEOUS INFORMATION 383

Approximate Bearing Capacity of Soils

Long tons per sq. ft. Bog and peat .. . . .. o to 0.2 Fine sand .. . . . . 2 to 5 Loam, marl and clay .. .. 3 to 7 Fine gravel 4 to 6

Coverage of Cement Mortar based on a thickness of 1 in.

sq.ft. 1 cu. ft. of cement.. . . ' . . 10.4 1 cu. ft. cement : 1 sand . . .. 17.0 1 cu. ft. cement : 2 sand . . .. 25.0 1 cu. ft. cement: 3 sand .. .. 34.0

Volume of Concrete from 1 cu. ft. Cement in various mixtures

Mixture Volume in cu. ft. 1 : 2 : 4 4.1 1 : 2½ : 5 5 1 : 3 : 6 5-8 1 : 4 : 8 7.5

UNITS OF PRESSURE OR HEAD

1 lb. per sq. in. = 2.31 ft. of water at 620 F. = 2.04 in. of mercury at 620 F.

1 ft. of water at 62° F. = 0.433 lb- Per sq. in 1 in. of mercury at 620 F. = 1.131 ft. of water at 620 F. 1 atmosphere (at sea level) = 14.7 lb. per sq. in.

= 34.0 ft. of water at 620 F.

NOTE.—Atmospheric pressure decreases approximately J lb. per sq. in. for every 1,000 ft. increase in elevation above sea level.

UNITS OF VOLUME AND WEIGHT

1 U.S. gal. = 231 cu. in. = 0.1337 cu. ft. = 8.35 lb. of water at 62° F. = 3.785 litres

1 Imp. gal. =1.20 U.S. gal. 1 cu. ft. = 7.48 U.S. gal.

= 62.4 lb. of water at 620 F. 1 acre-ft. =43.560 cu. ft.

= 325,829 U.S. gal.

A C K N O W L E D G M E N T S E. G. Baber, Colonial Sugar Refining Company, Sydney, N.S.W., Australia. F. H. B. Blackburn, Caroni Ltd. , Trinidad, B.W.I. Dr . B. A. Bourne, Vice-President, United States Sugar Corporation, Clewiston,

Florida. A. G. Carver, Colonial Sugar Refining Company, Sydney, N.S.W., Australia. D r . H. F. Clements, University of Hawaii. D r . H. H. Dodds, formerly Director, South African Sugar Association Experi

ment Station, Mount Edgecombe, Natal, South Africa. P. Halais, Curepipe, Mauritius. Dr . A. McMartin, Director of South African Sugar Association Experiment

Station, Mount Edgecombe, Natal, South Africa. C. I. McWhinnie, Hydraulic Engineer, Race Course, Jamaica, B.W.I. Juan B. Suris, Director, Cuba Sugar Year Book, Havana. Sir H. A. Tempany, C.M.G., C.B.E., Editor, World Crops. P. E. Turner, O.B.E., Sugar Agronomist, Development and Welfare in the

West Indies, Trinidad, B.W.I. Prof. L. F. Wiggins, Imperial College of Tropical Agriculture, Trinidad, B.W.I. T h e Secretary, United States Department of Agriculture, Washington D.C.,

U.S.A. M A N U F A C T U R I N G F I R M S

T h e Caterpillar Tractor Company. Fairbanks-Morse. International Harvester Company. Plant Protection Ltd. Ransomes Sims and Jefferies L td . " Shell " Refining and Marketing Co. Ltd. Sigmund Pumps Ltd. Turners Asbestos Cement Co. Ltd. Hunt ing Aerosurveys Ltd.

J O U R N A L S Agricultural Review, Mauritius. International Sugar Journal. Journal of the Jamaican Association of Sugar Technologists. Proceedings of B.W.I. Sugar Technologists Meetings. Report of the Sugar Industry Commission, Jamaica, 1944-45. Proceedings of the International Society of Sugar Cane Technologists. South African Sugar Journal. Sugar. Sugar Journal. World Crops.

BOOKS Agricultural Chemistry, ed. Dr . E. H. Frear. American Civil Engineers Hand Book. The Control of Water, Morley Parker. Fertilizers and Manures, Sir A. D. Hall . Ground Water, E. W. Bennison. Irrigation Engineering, Ivan E. Houk. Irrigation Pocket Book, R. B. Buckley. Irrigation Principles and Practice, Orson W. Israelson. Land Drainage, R. D. Kendall. Mechanized Agriculture, C. Davies. The Principles of Field Drainage, H. H. Nicholson. Queensland Cane Growers' Hand Book.

I N S T I T U T I O N S T h e Institution of Civil Engineering, Great George Street, London, S.W.i. T h e Science Museum Library, London, S.W.7. South African Sugar Association Experiment Station Library.

386

388 INDEX

390 INDEX

Paper from bagasse, 342 Parshall flume, 218-220 Peasant production, 152, 153 Pentachlorophenol, 185 Percolation losses, 212 Peru, 28 Pests of sugar-cane, 85-91 Philippines, 32 Phosphates, 169-172 —, application of, 172 —, effects of, 170 —, fixation in soil, 170 Phytalus smithii, 39, 91 Plans, survey, 120, 121 Planning, 113, 121, 124, 135, 296 Plantation organization, 298 Plant growth, elements essential to, 56,

57 , elements beneficial to, 57 , elements toxic to, 209

Planters' associations (see also Associations), 362

Planting, density of, 142 —, depth, 139 —, failures, 140 —, fall, 148 —, in Florida, 139 —, in Louisiana, 149 —, material, 49, 138 —, mechanical, 35, 141, 287 —, methods, 11, 138, 139 —, preparation for, 268 —, selection of varieties for, 142 —, spring, 148 —, time of, 141 Ploughs and ploughing, 136, 137 —, disc, 275 —, hitches, 275 —, moling, 68 —, mouldboard, 274 —, rotary, 276 —, subsoil, 276 Poison baits for rats, 10, 36, 88 Portable track, 284 Portacana transport system, 284 Potash (see Potassium) Potassium chloride, 174 — deficiency, 17s —, effects of, 173 —, fertilizers containing, 174 _ , rates and methods of applica

tion, 175 —, recovery from distillery waste, 344 — sulphate, 174 Preplanting treatment of setts, 140. Pressure exerted by track-type trac

tors, 269 — units of, 383

Prices of cane, computation of in Australia, 332

Natal, 333 Jamaica, 335 Puerto Rico, 337 Louisiana, 338

Production surveys, 315-317 Products of sugar-cane, 339 Propagation, 47 Puerto Rico, 10

fertilizers, 12 Government control, 13 irrigation, 11, 230, 232 production, 11 varieties of cane, 12

Pump(s) and pumping, 244-250 —, automatic control, 244 — characteristics, 248 —, discharge orifice, 247 —, power used for, 244, 245 —, subterranean, 250 —, turbine, 244

Quarantine, 83 Queensland agricultural practices, 34 — fertilizers, 35 — mechanical planting, 35 — pests and diseases, 36 — reaping and transport, 37 — weeding, 35

Railway(s), control, 197 — transport, 200, 284 Rainfall average, 321 —, effective, 210 — in relation to irrigation, 211 —, measurement of, 319, 322 Rain gauges, 319 Ratoons and ratooning, 47, 64, 100 —, cultivation, 146, 287 Rat(s) control, 87 — damage, 86 — poisoning, 10, 36, 88 Reaping, age at, 150 —, effect of previous operations on,

206 — groups, 205 — machines, 278-280 —, mechanical, 289 —, regulation of, 198 —, supervision of, 301 Records, 310 Rectangular weir, 221 Research, 299, 351 —, administration of, 356 —, earlier work, 352 —, financial control of, 357 — organizations, 354, 358

INDEX 391 Research projects, 355 —, planters' interests in, 352 — reports and publication of results,

357,359 — subjects, 355 Ripeness, testing for, 193, 195 Ripening control, 224 Road-rail transport, 119 Roadways, 261 Root-eating grubs, 91 Roots, 45 Rotary hoe, 277 Rotavator, 277 Row length per acre, 382 Rum, 344

St. Christopher (St. Kitts), 20 Salt accumulation in soil, prevention

of, 217 Secondary manufactures, location of,

348 Seed pieces (see Setts) Servicing of implements and tractors,

293-295 Sesbania spectabilis, io Setts (seed pieces), 49, 138 —, fungicidal treatment of, 50, 51 —, nodal, 288, 289 Sheeting, asbestos-cement, 128 Silt, 214 Sodium carbonate, 209 Sodium chlorate, 181 Sodium pentachlorophenate, 188 Soil(s), 52 — amendments, 63 — bearing capacity, 383 —, corrective treatment of, 176 —, cultural requirements, grouping

for, 59-61 —, function of, 55 — improvement by sugar-cane, 2 — moisture relationships, 65 —, origin of, 55 —, peat, 62 —, physical condition of, 64 — regeneration, 57, 58 — types, 53 Spacing, 138, 144 Sprayers, 187 Spraying for weed control, 187, 188 Spring planting, 148 Staff, 297-309 —, friction, 308 — qualities, 297, 300 — regulations, 305 —, research, 299 —, selection and training, 305-309 Stale cane, 200

Stalk, 45 Stone drains, 69 Subsoil ploughing, 137, 276 Sucrose, 31 , 339, 340, 348 Sugar-cane, description of the plant,

44 —, flowering of, 46 — propagation, 47 — roots, 45 Sugar producing countries, 6, 7 Superphosphate, 171 Supervision, 201, 205 Supplying, 140 Survey(s), 310 —, aerial, 115, 310 —, ground, 115 — plans, 120, 310

Taiwan, 32 Temperature, 323 Tenant farmer system, 38, 371 Thallium sulphate, 88 Thomson harvester, 280 Tile drains, 68 Tilth, 64 Toft harvester, 279 Tomaspis saccharina, 24 Torulopsis utilis, 345 Tournahauler, 283 Trace elements, 177 Tractors, track type, 255, 270 —, driving conditions, 273 —, equipment of, 271, 272 —, evolution of, 255, 256 —, implements for, 263-267 —, movement on highways, 272 —, operating requirements, 271 —, power considerations, 270 —, servicing and maintenance, 293,

294 —, wheeled, 273 Trailers, 281 Training of staff, 305-309 Transport operating procedure for

cane, 281,282 —, Portacana, 284 —, Railway, 197, 200, 284 —, Tournahauler, 283 —, tractor-trailer, 281, 283 Tramways, 284 Trash burning, 147 —, cultivation in, 146 — problem, 147 —, working in, 287 Trashing, 146 Trashy cane, 202 Trichogramma minutum, 90, 101 Trinidad, 24

392 INDEX

U b a cane, 92 U n d e r drainage, 69 Un i t ed States of America, 7 U . S . Sugar Corporation, 9, 75

Varietal changes, 109 Varieties, deterioration of, in —, early limitations on, 82 —, release of far planting, 107, 108 —, selection of, 99, 100 Vazcane, 342 Virus control of rats, 87 Volume, measures of, 384 —, units of, 383

Warfarin, 89 Wa te r (see also Pumping, and Irriga

tion) —, conveyance of, 212-214 — losses and wastage, 211, 212, 213 — measurement, 214, 218-222 —, night storage, 238 —, quality of, 209 — requirements by cane, 210, 211 —, underground, 239 —, weight per cubic foot, 382 W a x , 343 Weather records, 318-326

Weeding, 143 Weed killers (weedicides), 181, 184,

187, 192 —, 2 -4D, 184 Weeds, annual and perennial, 179 —, control from the air, 190 —, introduction and spread, 190, 191 —, investigations, 183 —, menace of, 178 —, methods of control, 143, 145. 1 7 9 _

190 —, pre-emergent control, 8, 186 —, suppression by cover crops, 191 Weights, measures of, 385 Weir, rectangular, 221 Wells, 238-241 —, open and closed, 240 —, characteristics of, 241 Wind, effect on cane, 102 —, velocity pressure, 127 Working animals, 131-134 Workshops, 130 World sugar crops, 6, 7

Yield of cane in Mauri t ius , 39

Zinc phosphide, 36, 88 Zinc sulphate, 63

Grub of root boring weevil (Diaprepes abbreviatus L.)

in defence of cane.

aldrin has been thoroughly tested against the sugar cane root boring weevil in Puerto Rico and other islands

of the West Indies. Those tests have proved that aldrin gives complete control of D. abbreviatus, whose grub

destroys the pithy centres of root stalks and decimates the cane.

Losses through weevil need not occur again, now that this pest can be controlled simply and economically by using a standard

fertilizer incorporating 0.25 per cent aldrin.

rin FULL INFORMATION FROM YOUR LOCAL SHELL COMPANY

MICROSOL Mechanical Fog Generator

This revolutionary equipment is now available from sterling sources. By virtue of its extreme simplicity, lightness and very high output without recourse to heat, steam or pressure, and its variable particle size, Microsol offers the Sugar industry in all parts of the world the finest protection against pests.

This protection can be obtained using any liquid or emulsion. By selecting one of the four current models it is possible to protect the product from the field to the finished syrup or packaged sugar.

It is interesting to note that new insecticides have been, and are now being, formulated for use wi th Microsol as a result of the greatly increased effectiveness of older types when used through our equipment.

Send for full particulars to :—

MICROSOL I N D U S T R I E S LIMITED Carlisle House, 8 Southampton Row, London, W.C.I

Tel.: CHANCERY 8172

SILVER CREEK PRECISION CORPORATION 50 Broadway, New York, 4, N.Y., U.S.A.

Tel. : DIGBY 4-0137

SUGAR GROWERS

WE SPECIALISE IN WEEDKILUNG and a re able,

through our Technical D e p a r t m e n t , to offer you the advice which wi l l rel ieve you of your weedkil l ing worries.

As manufacturers of most of the herbicides in use to-day, we have experience in weed-kill ing all over the world and in many different types of crops.

The results of this experience are available on application and we welcome your enquiries.

UNIVERSAL CROP PROTECTION LTD. BALTIC HOUSE, LEADENHALL ST., L O N D O N , E.C.3., ENGLAND

Telephone: Royal 5611-7

Telegrams: Unicrop, Telex, London

Foreign : Unicrop, London, Telex, Royal 1019

SUGAR MACHINERY

FOR EVERY STATION OF THE SUGAR FACTORY

Fletcher built plant is outstanding in its advanced design and lasting dependability combined with efficiency and economy in operation.

mzM

HUDSON Cane Cars for reliability under all conditions

10 tons cap., 75 cms. rail gauge.

3-6 tons cap., 4-wheel type, 60 cms. to 30" rail gauge.

Double bogey types also from 8-15 tons capacity for 60 cms. to I metre rail gauges.

Hudson—'Hunslet Diesel Locomotive. 21 h.p., 3 1/4 tons.

Robert Hudson Ltd. , Raletrux House, Meadow Lane, Leeds, 11 Tel. : Leeds 20004

London : 47 Victoria Street, S.W.I . Works at Leeds, Benoni, Durban and Calcutta. Grams.: Raletrux (all offices).

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