Irrigation farming on the Liverpool Plains
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Irrigation farming on the Liverpool PlainsJ. J. J. Pigrama University of New EnglandPublished online: 24 Feb 2007.
To cite this article: J. J. J. Pigram (1969) Irrigation farming on the Liverpool Plains, Australian Geographer, 11:1, 90-93, DOI:10.1080/00049186908702540
To link to this article: http://dx.doi.org/10.1080/00049186908702540
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The Australian Geographer, XI, 1(1969), pp. 90-93
THE AUSTRALIAN SCENE
IRRIGATION FARMING ON THE LIVERPOOL PLAINS
Until recently, irrigation has been a minor featureof agricultural landuse in the middle NamoiValley. Irrigated areas were scattered along theriver banks between the Peel River junction andBoggabri and in general were limited to naturalor sown pastures and small areas of fodder crops.Bores sunk in the alluvium within the NamoiValley and its tributaries were shallow and fewproduced a surplus beyond that required for astock water supply. However, between 1964 and1968, great expansion has taken place, both inthe area irrigated and the number of irrigators.This expansion has been made possible, in part,by river frontage properties taking advantage ofregulated flows in the Namoi following the com-pletion of Keepit Dam, but more significant hasbeen the increasing use of groundwater in partsof the Liverpool Plains more distant from theriver. Accompanying the spread in the practiceof irrigation has been a change in farming em-phasis in certain areas, with several irrigatorsadopting techniques of row-cropping, and diversi-fying output by growing a variety of grains andoilseed crops.
These developments have taken place with littleofficial recognition or supervision and few recordsare available as to the extent of irrigation or theholdings involved. The author, therefore, isundertaking a survey of farms within the Liver-pool Plains Shire. To date, 125 properties withirrigation have been surveyed, which correspondsto the number of irrigated holdings quoted by theCommonwealth Statistician for the same region.Specific information is being sought on the per-sonnel actively engaged in irrigation, the locationof areas irrigated, the range of irrigated productsand efficiency of watering methods, the location ofirrigation bores and their effect, if any, ongroundwater reserves.
Preliminary results of the survey reveal that,within the Shire area, irrigation is confined tothree zones:1. The valley of the Namoi River, both north
and south banks, where irrigation is carriedon using river and/or groundwater supplies,from east of Carroll north-west to Boggabri.Some successful bores have also been sunk inshallow alluvium in the Wean and Kelvinvalleys to the north of Gunnedah.
2. The Breeza Plain, flanking the non-perennialwatercourse of the Mooki River from Caroonanorth to Gunnedah, where farms irrigate en-tirely from groundwater.
3. The narrow stretch of alluvium and water-bearing gravels along Cox's Creek (non-peren-nial), from Premer north to Boggabri.
A total of 47 pumps have been installed on 37holdings along the section of the Namoi Riverwithin the Shire. Of these holdings, 12 rely en-tirely on river water for irrigation and another 8pump from the river, in addition to using ground-water. The remaining 105 farms irrigate ex-clusively from bores. In the Shire area, 200bores or wells are used for irrigation and thepotential water supply from these sources is esti-mated to be 5,251,900 gallons per hour. Thesetotals disregard the many stock bores tappingshallow aquifers, as well as an additional 21bores, inactive at present, but capable of pro-ducing an irrigation supply (put at 5000 g.p.h.or more).
Individually, few bores produce spectacularflows, when considered relatively to the greatvolumes of water currently being obtained fromdeep, well-equipped bores further west in thelower Namoi Valley. Four bores were stated bylandholders to yield more than 100,000 g.p.h.,with the most productive at 210,000 g.p.h. Sev-eral small-scale irrigators could give no reliableestimate of bore flows. In most cases, low out-put could be attributed to a combination of in-sufficient test-drilling, unsuitable sites, poor drill-ing methods, inadequate bore development priorto use, lack of test pumping, poor pump selectionor maintenance, badly equipped bores or unsuit-able operational procedures.
It is apparent that improved bore constructionand fittings, although expensive, would result ingreatly increased water output. Such measures,coupled with instruction in operating techniquesand efficient application and drainage methods,could add considerably to the potentially irrigablearea and to crop yields.
Table 1 summarizes irrigation acreage by zone,season, application method, crop type and watersupply. Although the greatest number of hold-ings with irrigation is in the valley of the Namoiand adjacent areas, the average acreage there
THE AUSTRALIAN SCENE 91
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92 THE AUSTRALIAN GEOGRAPHER
Table 1DISTRIBUTION OF IRRIGATION ACREAGE AND WATER SUPPLYLIVERPOOL PLAINS,
Namoi Breeza Cox'sValley Plain Creek Totals
Acreage irrigated:Summer 5,184 5,662 915 11,761Winter 1,964 2,293 946 5,203
Total 7,148 7,955 1,861 16,964
Holdings 76 30 19 125Average area irrigated 94.1 265.2 97.9 135.7
Irrigation system:Spray 4,060 1,117 794 5,971Flood-bay 1,014 1,985 440 3,439Corrugation 788 90 150 1,028Furrow 1,286 4,763 477 6,526
Irrigated crops:Sorghum 1,852 2,703 560 5,115Wheat 1,079 1,485 452 3,016Corn ....../. 1,240 1,240Barley 453 628 286 1,367Oats 422 180 108 710Lucerne '. 1,694 674 144 2,512Sudax, etc 660 485 163 1,308Natural pasture 875 180 88 1,141Other* 115 380 60 555
Water supply:Irrigation boresTotal 106 79 36 221
Active ' 99 70 31 200Potential capacityg.p.h 2,378,900 2,098,000 775,000 5,251,900
River pumpsTotal: 47 on 37 holdings.Active: 30 on 20 holdings.
* Other crops include: soya bean, sunflower, millet and pure seed crops.
irrigated by individual farmers is the smallest ofthe three zones. The general picture is one ofsupplementary irrigation of limited areas, usuallyas 'drought insurance', with 62 irrigators usingsprays; 52 use sprays to the exclusion of anyother method. There are exceptions to this pat-tern, notably irrigators using river water on thenorth bank of the Namoi and near Boggabri. Ifthese 11 larger operators (200 or more acresirrigated) are excluded, the average drops to62.1 acres.
It is on the Breeza Plain, however, that irriga-tion farming has brought about the greatest changein the agricultural landscape. Although irriga-tors number only 30, total irrigated acreage is thelargest of the three zones and average area perfarm irrigated annually is 265.2 acres. Thecontrast with the Namoi Valley is brought out
further by the systems used for irrigation. Inthis zone, 22 irrigators use furrow or 'corru-gation' methods (widely spaced furrows) for row-cropping of coarse grains such as sorghum andmaize, with smaller plots of oilseed crops. Sprayoutfits are used on 13 holdings, but only 4 farmsuse this system of watering exclusively. In fact,most of the holdings surveyed on the BreezaPlain can properly be described as 'irrigation'farms, with the whole farm economy revolvingaround irrigation in a completely integratedenterprise.
In the third zone, Cox's Creek, the averagearea irrigated annually per farm is 97.9 acresand represents a mixture of grains, fodder cropsand pasture. Irrigated land extends in a dis-continuous belt for 50 miles, generally on theeastern bank of the creek. The aquifers are
THE AUSTRALIAN SCENE 93
restricted to the immediate vicinity of the water-course in most cases, and have proved to belimited in quantity and quality.
The dominant crop irrigated on the LiverpoolPlains is grain sorghum and in the 1967/8 sea-son yields of over three tons per acre have beenrealized, with the stubble left after harvest pro-viding valuable grazing. A cooperative has beenformed as a step toward orderly marketing,although a considerable amount of the currentcrop was grown under contract to Japanese buy-ers. The high acreage for irrigated wheat couldbe misleading, as this figure may represent onlyone or two supplementary waterings through thegrowing season. Once again useful winter graz-ing is provided before the crop is brought tomaturity in the spring. Lucerne is by far themost important and widely grown fodder crop,with nearly half the surveyed holdings (59)having some lucerne under irrigation. A dis-turbing feature is the large acreage irrigated ofnatural pasture, generally considered of doubtfulgrazing value and wasteful of water.
It can be seen that two major types of irriga-tion farming have developed on the LiverpoolPlains accompanying the recent vipsurge in theexploitation of groundwater. The practice ofsupplementary irrigation, although individuallylimited, has become widespread. Even.so, apartfrom providing greater security during dry peri-ods, this type of irrigation has done little todisturb the predominant farming emphasis in theregiondryland cropping of wheat and grazingof sheep and cattle.
However, the advent of intensive irrigationfarming on a large scale poses many problems.
The impressive yields already achieved have de-monstrated the value of row-cropping with anassured water supply, but at the same time havecontributed to rising land values with accom-panying increases in taxes and rates. Both arepowerful incentives to encourage even more in-tensive use of irrigable country.
Nevertheless, irrigated land is discontinuousand not all farmers have introduced irrigation,even in known favourable areas for groundwater.In these cases, doubts on the part of 'traditional'landholders concerning the potential of the aqui-fers to withstand long-term heavy withdrawalshave reinforced scepticism regarding the econ-omics of investing great amounts of capital inthe specialized equipment and land developmentnecessary for large-scale irrigation; especiallywhen markets for irrigated products are in astate of uncertainty.
Finally, many long-established dryland farmersare not prepared to adopt the revolutionarychanges in work patterns essential for a successfulirrigation enterprise. At the same time, they ap-pear to resent the initiative and the success oftheir irrigator neighbours, especially if this canbe linked to any apparent or alleged detrimentaleffect on their own groundwater supplies.
Before these viewpoints can be reconciled,much more specific information is necessary ongroundwater occurrence and behaviour, so thatareas of adequate reserves, both in quantity andquality, may be denned more accurately, and areasoned assessment made of the potential ofirrigation agriculture on the Liverpool Plains.
J. J. J. PigramUniversity of New England