Published by the Tropical Grassland Society of Australia Inc306 Carmody Road, St Lucia Qld 4067

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Tropical Grassland Society of Australia Inc.

about pasture development in the tropics and subtropics

news&

views

Newsletter editor:Ian PartridgeTel: (07) 4688 1375Fax:(07) 4688 1477ian.partridge@dpi.qld.gov.au

Turf—the sleeping giant?Don Loch, DPI Redland Bay

The Tropical Grassland Society is seekingto broaden its membership and scope ofthe Newsletter and Journal to embraceother uses of grasslands and grasses awayfrom the traditional area of animal graz-ing and feed supply. New areas might in-clude the use of grasslands for environ-mental improvement (e.g. rehabilitation ofmining sites, revegetation of creek banks,

erosion control), bio-remediation (e.g.sewerage/grey-water disposal), and theuse of grasses for turf (golf courses, play-ing fields, parks, landscaping, and homelawns) and for amenity purposes (road-sides, city landscaping, urban gardens, flo-ral displays).

John Wilson

The first of John’s technical articles onshade appears on page 6.

For too long, the turf industry in Australiahas been like Cinderella before the ball.While research on improved pastures inQueensland powered ahead with largeresearch teams during the 1970s and 1980s,we had only one scientist working part-time on turf and amenity grasses in DPIand no one at all in CSIRO and the uni-versities. Some pasture scientists even be-grudged giving up this level of resourcesto something that they did not regard as a“real” agricultural pursuit.

But over the past decade or so, the fundsthat drove our earlier research into pas-tures have progressively dried up. Redun-dancy and retirements without replace-ment have eroded the key skills that keptus at the cutting edge of pasture researchinternationally. No one in authority seemsto value any more the food and fibre thatpastures generate. All of this is well knownand has been of increasing concern to theTropical Grassland Society.

What’s the sodding future?So does turf research have a place in thefuture of the TGS as we seek to broadenour horizons? I believe that it does havenot just a role but a key role in shapingthe future of tropical grassland science inQueensland and Australia. We should notforget our roots in pastures, but the TGSof the future needs to become a muchmore broadly based Grassland Societyrepresentative of the whole range of grass-land-related activities.Turf “sells” the one thing that a popula-tion with plentiful supplies of food andfibre still values—lifestyle. This comesthrough home lawns, roadside plantings,parks and urban open space, golf, bowlsand other sports facilities, even cemeter-ies.

Turf and other parts of the amenity sectorare large industries, both individually andcollectively. Moreover, they are growingrapidly and becoming more professional

continued on page 3

2 TGS News

Society NewsOur Internet address

www.tropicalgrasslands.asn.auSee it for membership forms, an updated book list and pdf versions of the newsletter.Our Society e-mail address is tgs@csiro.au

PresidentDavid OrrQueensland Beef Industry InstitutePO Box 6014, Rockhampton Mail Cen-tre, Qld 4702Phone: 07 49360238 Fax: 07 4923 8222e-mail: david.orr@dpi.qld.gov.au

Vice PresidentBruce CookDPI, PO Box 395Gympie, Qld 4570Tel: 07 5480 4421; Fax: 5482 1529e-mail: bruce.cook@dpi.qld.gov.au

Past PresidentCol Middleton, Rockhampton

SecretaryShaun LissonCSIRO Sustainable Ecosystems306, Carmody Road, St Lucia 4067Phone: 07 3214 2363Fax: 07 3214 2308e-mail: shaun.lisson@csiro.au

TreasurerBen MullenSchool of Land & FoodUniversity of Qld, St Lucia Qld 4072Phone: 07 3365 3474Fax: 07 3365 1188e-mail: b.mullen@mailbox.uq.edu.au

Journal EditorLyle WinksMcNeills RdMS 825, Ipswich, Qld 4306Phone: 07 5467 2314Fax: 07 5467 2314e-mail: lwinks@gil.com.au

Newsletter EditorIan PartridgeQDPI, PO Box 102Toowoomba Qld 4350Phone: 07 4688 1375Fax: 07 4688 1199e-mail: ian.partridge@dpi.qld.gov.au

Your Executive for 2003

Not again!

I have to apologise for another late news-letter but its preparation has had to fitaround my other work demands. Dur-ing March, I was in southern Vietnamwith Bruce Cook and others helping torun a series of training courses on foragedevelopment for the local extension of-ficers and farmers of the Quang Ngai

We have been having a few technicalproblems getting the Pasture Picker ontoour Web site. This has involved compli-cations with the interactive database and

Pasture Pickerthe requirements of the server providers.

But we should be there soon.

Department of Agriculture and Rural De-velopment. They know everything aboutgrowing rice but forages, other than ele-phant grass, are something new.The enthusiasm for learning over there andthe reception they provided makes we oldpasture agronomists feel loved again!

Yoursubscriptionsare due again

TGS News 3

in response to local demand and to exportopportunities for amenity-related goodsand services particularly into Asia and theMiddle East.

$50 M for sod and seed in QueenslandTurf is not simply a supply chain (as thecurrent jargon would put it), but more ofa supply loop. The sale of vegetative sod,sprigs or seed to establish a new area ofturf only initiates a much larger and on-going process of management (mowing,fertilising, irrigating, controlling pests) thatcontinually adds value and creates a muchlarger industry overall. The $50-60 millionannual sales of sod and seed in Queen-sland are actually part of a billion-dollarturf industry in this state.

Mega bucks for turf in the USThe US gives an inkling of where thegrowth of our turf industry could take usin the future. The most recent estimates(based on economic surveys now someyears old) put the value of the US turf in-dustry in 2000 at US$62 billion. It is theirbiggest land-based industry. Even in Tex-as, the turf industry is bigger than cottonand bigger than beef. And to put all of thisinto even better perspective, in the sameyear (2000) the motion picture and soundrecording industry was worth US$57.8 bil-lion to the US economy.With all the mowing, fertilising, irrigatingand the like going on, the turf industry isalso a major employer among primary in-dustries. This gives it considerable lever-age on “hot” issues such as water rights asseen recently in the US and even in West-ern Australia.

Jobs for grass scientistsProfessional TGS members will be interest-ed in the fact that the US turf industryemploys large numbers of tertiary-trainedpersonnel. Currently, one in three mem-bers of the Crop Science Society of Ameri-ca work in turf—hence the need for theAustralian organisers of the 2004 Interna-tional Crop Science Congress in Brisbaneto accommodate their interest within theCongress program. In US universities, 35-40% of undergraduates in whichever De-partment (Agronomy or Horticulture) of-fers turf courses are turf majors.

The natural progression in grass seedmarkets in other developed countrieshas been from forage to turf use. Ore-gon’s Willamette Valley—the so-calledgrass seed capital of the world—startedoff growing seed of pasture cultivars, butnow 70% or more of its production com-prises turf cultivars. The main speciesgrown are still tall fescue and ryegrass,but almost all of the breeders who usedto produce improved forage varieties ofthese grasses have moved on to othercrops or moved over to turf breeding.

Similar problems for pasture and turfPasture and turf research are not, andshould not be, mutually exclusive areas.They share many of the same species,research topics and issues.

Diseases. Kikuyu (Pennisetum clandesti-num), for example, is the main grass usedon racetracks in southern Queenslandand northern NSW; and as with kikuyupastures one of the main problems is thedisease kikuyu yellows.In the case of blue couch (Digitaria di-dactyla), we are really only mowing ashort pasture grass. There are far bettertypes for turf and for forage use, andonly recently has some of the better turfmaterial been exploited through im-proved cultivars.

Winter growth. At Redlands, we are see-ing the same differences in winter dor-mancy and activity between cultivars ofthe major turf grasses that were recog-nised in our pasture grasses (e.g. Pani-cum coloratum) decades ago. In Queen-sland, we need winter-active pasturegrasses and winter-active turf grassesthat can take advantage of our warmwinter days. This is in direct contrast tothe situation in much of southern USA(and eastern Asia) where a degree ofwinter dormancy in cultivars of the samespecies helps their winter survival dur-ing extreme cold snaps.Shade. Shade affects around 25% of turf-grass sites, and so has been extensivelystudied by turf researchers. Much of thisliterature is also relevant to pasture re-searchers seeking to grow forage grass-es under trees (see article on page 6).

4 TGS News

Water use efficiency. Australia is the driestinhabited continent with only 1% of theworld’s surface water. How best to use thiswater, conserve it and recycle it is increas-ingly important for both pastures and turfuse. Again, the extensive literature onwater relations and use in turf grasses isrelevant to pasture studies, and vice versa.Salt-tolerance. Seashore paspalum(Paspalum vaginatum) was first used as pas-ture grass for salty seepages in WesternAustralia during the 1950s, but its devel-opment since has been as a turf grass high-ly tolerant of salt—with the best cultivarstolerant of the levels of salt in sea water.

The salinisation of previously productiveland is not just a high priority issue forpastures and other agricultural crops, it isalso important on an increasing numberof turf grass sites. Research has shown howbest to manage salt-affected turf grass sitesand avoid the further accumulation of salt.We now have turf grasses that will not only

tolerate high salt levels in the soil and/orirrigation water, they also look good. Inmany cases, however, it is not sufficientjust to look good; there may also be a needto generate income through hay or graz-ing to make the solution economically vi-able. With salt as with so many other is-sues, we need a range of solutions fromwhich people can choose the one that bestmeets their economic or aesthetic needs.For grassland science in general, turf pro-vides the opportunity to preserve techni-cal skills that are also vital to the successof pasture research. At Redlands, for ex-ample, we already have a plant patholo-gist and a plant nutrition specialist work-ing on turf—skills that are not readilyavailable in pasture programs these days.

So next time you watch a State of Origingame on TV, don’t just look at how goodthe players are. Check out how the turfthey play on is holding up. This just mightbe your future.

Bruce Cook, your Vice President,describes the potential for someimproved forage species in QuangNgai Province,South Vietnam.

A Vietnamese farmer washeshis pride and joy in the river

in Pho An district.

TGS News 5

Grasses can be found over nearly everysquare kilometre of land on the continentof Australia—from the tip of Cape York tothe south of Tasmania, from east to west.They can be found over natural grasslands,under woodlands and forests, in fact wher-ever plants can grow. And yet, they areamongst the most neglected families whenit comes to botanical studies.There are 1323 species of grass, both na-tive and naturalised, that can be foundgrowing wild in Australia and yet howmany of us know more that a handful?

AusGrass

A new guide to identifying any of these1323 grasses has been published as an in-teractive database. AusGrass is the largestand most comprehensive identification toa plant group ever produced. Using eitherinteractive or dichotomous keys, you canquickly identify any of the species foundin Australia. And you can use it with liv-ing or dry specimens, even if they don’thave flowers or seed.

This grass database is based on the latestweb-integrated Lucid Player to providecomprehensive fact sheets for each species,including a botanical description, notes onits distribution and taxonomy, as well asimages including diagnostic line drawings,scanned specimens, photographs and ster-eomicrographs. The photographs of the in-florescences of many species are excellentand almost works of art; anyone who hastried to photograph living grasses as theywave around in the breeze to obtain close-ups with good depth of field must attestto the patience and skill involved.AusGrass has been developed by DonovanSharp and Bryan Simon from the Queen-sland Herbarium. It is published as a jointventure between CSIRO Publishing, theAustralian Biological Resources Study andthe Queensland Environmental ProtectionAgency.

The CD-ROM and the manual cost $99.00.

Poaceae flora

Also released in a new Flora of Aus-tralia Volume 43. Poaceae 1: Introduc-tion and Atlas.

This provides an overview to thegrass family and to grass biologyin Australia. The book containsessays that review the latest Aus-tralian research on phylogeny,classification, anatomy, physiol-ogy, ecology, palaeobotany andbiogeography of the Australiangrasses, with a further chapterhaving a detailed synopsis ofthe economic attributes ofgrasses on a genus by genus ba-sis.Besides identification keys, the volume in-cludes an atlas with more than 1400 mapsshowing the distributions of the nativeand naturalised species.

How to get your copiesThe Flora costs $100 for a hardback edi-tion or $85 for a paperback.Both publications can be obtained fromCSIRO Publishing, PO box 1139Collingwood, Vic 3066.

Freecall (in Australia) 1800 645 051; e-mail: publishing.sales@csiro.au.Check the details of this and othergrassland books on their web site atwww.publish.csiro.au.

And don’t confuse AusGrass withAussieGrass, which is theQueensland Department of NaturalResources and Mines productshowing maps of present andforecast pasture growth overAustralia.

Other books for identifying grassesfound in Queensland’s tropical andsubtropical regions include The Grasses ofSouthern Queensland (with line drawing ofover 400 species for $50 from TGS BookSales) and Jenny Milson’s full colourPasture Plants of north-west Queensland(only $45 from DPI Book Sales)

Know those Aussie grasses

CD-ROM

Book

6 TGS News

In this series of articles, John Wilson, for-merly plant physiologist with CSIROTropical Agriculture, describes the prob-lems of trying to grow turf under shade.The following article discusses one of themore difficult aspects of turf development.

Why can’t I grow good grass under shade?

This is a question often asked by garden-ers, landscapers and greens keepers andis exaberated by the trend towards sun-protective shade cloth areas at schools,public parks and pools.

Of course, the response of grass to shadeis highly relevant to tropical pasture per-formance in tree plantations and savan-na woodlands.

Shade

Light level. Incident radiation (sunlight) istraditionally measured as total short waveradiation (SW). Of more interest for plantgrowth is photosynthetically active radi-ation (PAR) of 400-700 nm wavelengths).In the past decade, integrating PAR me-ters have become commonly available;these can be placed in fixed positions andlogged over days or months, or more use-fully for tree shade areas be a hand-heldtype that is walked around the survey areafor 5 minutes or so—integrating the lightover the sunny and shady patches.In full sunlight and under most artificialshade cloths, PAR = c. 0.5 SW, but maybecome PAR= 0.27SW at grass level un-der dense tree canopies because the treeleaves absorb PAR.

Some examples of climatic zone and sea-sonal variation in daily inputs of incident

PAR can be seen in Table 1. Incident radia-tion for the wet tropics is similar through-out year, but in winter in the subtropics itis about 60% of summer levels even with-out shade and in the cool temperate zoneas little as 20% of summer. So shade im-posed in winter will have a major impacton grass growth in the latter two climaticzones.

Shade from buildings (e.g. grandstandsand highrises) may decrease light input byonly 30% in summer, but in winter withlow sun angles and the lower incident ra-diation (Table 1) the decrease could be asmuch as 80% of normal summer light. Forwinter sports this shade creates great prob-lems, especially as lower temperature re-stricts turf growth anyway. Under trees,the situation may be different because theircanopies (and thus shade) may be heavierin the summer growing season than dur-ing winter when leaves may be lost. I havemeasured under trees in my own gardenPAR levels as little as 2–10% of incidentlight in summer, but in winter the lightreceived by the lawn may increase to 50-60% of summer levels because of leaf drop.Typically, light received by grass under treeplantations may be 40-60% of full sun foreucalypts and coconuts, but as low as 10%in dense rubber and oil palm.Light quality. The proportion of red, blueand infra-red is little changed under shadecloths and in shade from buildings. How-ever, under trees the red and blue wave-lengths are preferentially absorbed by treeleaves for photosynthesis and the R/FRseen by the understorey grasses maychange from the level of about 1.2 in full

Shady corner‘Why can’t I grow good turf under shade?’

John Wilson, previously CSIRO pasture plant physiologist

Table 1. Daily values for incident PAR (MJ m-2 d-1)

Climatic zone Season of year

Summer Autumn Winter Spring

Wet tropics 8.9 9.7 8.9 8.7

Subtropics 10.8 7.8 6.8 10.3

Cool temperate 7.8 3.2 1.5 6.4

TGS News 7

sun to as low as 0.43 under rainforest canopies (Ta-ble 2). The change is greater under dense tree can-opies as under mature rubber plantations than un-der more open canopies such as eucalypts and co-conut plantations.Air and soil temperature. Generally air temperatureat grass height under tree or artificial shade is only1–2 °C lower than in full sun, and leaf temperaturesmay also be 1–1.5 °C lower. However, maximumsurface soil temperatures under shade can be dra-matically lower than in full sun by as much as 10°C,and even up to 20 °C on very hot days. Shade fromtrees or cloth cover may lessen the degree of radia-tion frosting on grass. Shade may also slow the riseof soil temperatures in spring. As a rule of thumb,tropical grasses cease growing when the minimumair temperature or surface soil temperature is lessthan 12°C.

Soil water status under shade. Air relative humidityunder shade at grass height may increase but anyinfluence is likely to be small (1–5% units) unlessthe shade canopy is very close to the grass. Becauseair, leaf and soil surface temperatures are decreasedunder shade, evaporative demand may be slightlyreduced and the rate of soil drying slower than infull sun. Consequently, under artificial shade thesoil may stay moister for a little longer after rainfall.However, under trees whilst the initial soil dryingafter good rainfall may be slowed, the extra evapo-rative demand of the tree canopy (unless the tree isdeep-rooted) will soon dry out the soil in the grassroot zone, sometimes to an even drier status thanunder grass in full sun, thereby causing great stressto understorey turf or grass growth. In addition,the tree canopy may prevent small falls of rain fromreaching the soil, or may channel rainfall down thetrunk to concentrate it in a zone near the tree base—both causing problems for grass growth.

Grass response to shadeIf there are no other restrictions to growth (whichis rare but may occur on intensively managed golfcourses), the rate of photosynthesis and hencegrowth of tropical grass or turf is decreased moreor less in direct proportion to the amount of light(PAR) received. Often, however, there are some re-strictions, such as low temperature or lack of wateror nutrients, and the photosynthetic light response

Table 2. Red/far-red ratios of light under various shade situations

Full Mature Coconut Eucalypts Mature Shade cloth Shade clothsun rubber trees trees (8 yr-old) Rainforest -green (70%) -black (50%)

1.2 0.62 1.03 1.2 0.43 1.03 1.1

This series by John will be continured in the next issue

curve is light-saturated at not more than about 60–70% of full light. In some of these situations, al-though shade may have reduced light levels to say60% of normal, there will be little decrease in growthand sometimes none at all. The latter may occurbecause evaporative demand is reduced or becausesoil nitrogen availability is improved.

Many tropical pasture or turf grasses normallygrown under full-sun situations can cope reasona-bly with shade down to about 50% provided theyare carefully managed—albeit with reduced growth.There are always exceptions, and within the majorturf species the Cynodon species. and blue couch(Digitaria sp.) seem to cope poorly with just aboutany level of shade.Below about 50% light, turf grasses need to be cho-sen for their special shade tolerance, and it is myjudgement that only a few species will make suc-cessful turf below 20% light. A discussion of shadetolerance of different turf grass species and culti-vars will be the subject of another article.

Morphological changesShade inevitably causes changes in the morpholo-gy of most grasses—stems elongate, leaves becomethinner, broader and, in many species, more erect.Growth of the plant tops is favoured at the expenseof less root growth, and the density of shoots (till-ers) is much reduced. Thus it is hard to get a gooddense turf under shade. A decrease in R/FR, as un-der dense tree canopies, adds to the extent of thesemorphological changes. These modifications areaimed at intercepting more light to assist success innatural ecosystems. But they are counterproductiveto the sustainability and digestibility of grasses usedin grazed pastures or to the maintenance of strong,high-quality, thick turf. This is because the photo-synthate preferentially allocated to tops is continu-ally being removed by mowing or grazing, causingprogressive weakening of individual plants, espe-cially in very dense shade. The lower proportion ofroots makes the grasses more susceptible to soil dry-ness, a major problem when in competition withtree roots under tree canopies. Management is there-fore a key issue for keeping good turf under shadewhether on sport arenas or in the home garden.

8 TGS News

Leucaena in ParaguayIn the last Tropical Grasslands Newslet-ter, Ian Partridge described his experiencein Paraguay. In this contribution, I willdescribe my impressions of what I saw ofLeucaena in a brief but very intensive vis-it, mainly to the central Chaco region.I was invited by the project INTTAS (Ini-ciativa para la Investigación y Transferen-cia de Tecnología Agraria Sostenible),sponsored by the AVINA foundation andoperating in the Chaco. They specificallywanted me to introduce the DHP-degrad-ing bacterium Synergistes jonesii to the cat-tle there.

My hosts in the Chaco were Dr AlbrechtGlatzle and Mr Antero Cabrerra (Nikki tohis friends). We were accompanied on thevisits for most of the trip by an old ac-quaintance Ing Maria Goldfab who is anecologist working in Argentina.

Bugs beside meI carried the precious ‘bugs’, in rumen flu-id from steers at Lansdown Research Sta-tion, in a stainless steel thermos flask in-side an insulated container in the cabinwith me—with permission from Qantas.Other documentation from quarantineauthorities in both countries enabled thesuspicious-looking container to passthrough the numerous scanners at thevarious airports; it was never like this be-fore September 11!

I arrived at 5 p.m. and had to get the ‘bugs’into the prepared fistulated steers as soonas possible. It took 6 hours to travel fromAsuncion to the Central Chaco Experi-ment Station—on a road full of potholes,in pouring rain and with spectacular light-ning. We arrived after midnight and thetwo fistulated steers, that had been fed onleucaena, were infused with the ‘bugs’ by1 a.m.

Leucaena in the ChacoDuring the ‘gestation period for the bug’,I visited blocks of leucaena around thetown of Filadelfia. This part of the Chacois a flat flood plain originally covered withmainly Acacia and Prosopis scrub. Manytropical legumes are well adapted to thesandy soils but fewer on the heavier tex-tured soils, with leucaena the most prom-ising. One of the most noticeable featuresof the area was the number of small andlarge ant nests. Fortunately, we do nothave these leaf-cutting ants in Australia.Some are specialist grass cutters and oth-ers prefer non-grasses, including leucae-na. The once-popular star grass (Cynodonspp.) is rarely planted now because theants favour it. Ant control is vital to thesuccessful establishment of leucaena inmany areas.

2 metres high in 6 monthsI was most impressed with the healthygrowth of leucaena on these farms. As inAustralia, weed control is vital for rapidestablishment and, where this had beenachieved, some of the growth was spec-tacular, with 6-month old leucaena over 2metres tall. Cunningham has been themost widely planted cultivar to date butstands of Tarramba were being kept forseed production. Many of the newly es-tablished stands over 2 m tall would havebenefited from an earlier grazing or top-ping to stimulate basal branching.

Peter Larsen had visited Paraguay andsome farmers from Paraguay had visitedAustralia, so they had grasped the basicsof leucaena establishment and most leu-caena has been sown in double rowsspaced 5-8 m apart.

Raymond J. Jones, formerly CSIRO pasture researcher

Young leucaena with Gattonpanic in the Chaco

TGS News 9

However, on one farm, leucaena had beenestablished well by simply oversowing,just as we would with Seca stylo. Howev-er, I can foresee problems with manage-ment as Acacia and Prosopis seedling werere-establishing among the leucaena andare not easy to spot; also there is a poten-tial for a thicket to form, and slashing tocontrol height will entail slashing thewhole paddock with a strong risk of punc-turing the tractor’s tyres. With a thick cov-er cattle can become very ‘flighty’, and arenot easy to see. As this can encourage theft,farmers do not like planting leucaena nearboundaries. Planting in rows so that cat-tle can be spotted from the homestead orexisting roads would therefore be the pre-ferred option.

NodulationMost stands, except some in lower lyingareas that had experienced some water-logging, had dark green leaves suggest-ing that they were effectively nodulated.It was claimed that they nodulate natu-rally, possibly from strain of Rhizobiumfrom the original vegetation of legumi-nous shrubs and trees. However, wecould find no nodules on seedlings, eventhose adjacent to old leucaena.

Mimosine toxicityAnimal production was being measuredat only a few sites. Their experience wassimilar to ours in the 1970s and early ’80sin tropical Australia. Steers grew rapidlyat about 1 kg/day for about 2-3 months,then stopped or lost weight and animalslost hair. New animals on the same pas-ture, or animals that had grazed grass pas-tures, and were returned to the leucaenapastures, continued to gain at about 1 kg/day. No thyroid measurements had beenmade, but I suspect that animals from leu-caena pastures would have had higherthyroid weights than the normal 20-25 gand their serum thyroxine levels wouldhave been low. Clearly the animals do nothave DHP-degrading bacteria. Freeze-dried Synergistes jonesii (strain 78-1), fromDr Milton Allison in USA, was introducedto fistulated cattle a few years ago and es-tablished in them. However, they wereunable to transfer it to cattle on otherfarms, and obviously the fistulated cattleon the research station have not retained

it. The rumen fluid I brought from steersat the CSIRO Lansdown Research Stationtook 8-9 days (compared with the usual 5days) to completely destroy the toxin, butat least it is working in these steers. It willbe interesting to follow the fate of the bac-teria when transferred to cattle on the var-ious properties. The impact on animal pro-duction should be very large and it willremove the fear about the toxicity that canhinder acceptability.

Leucaena’s potentialCurrently there are about 2,000 ha sownto leucaena, but there could be some 10million ha suitable in the central Chacoregion (700-900 mm MAR). It will be ofgreat value for intensifying beef and dairyproduction on the relatively small farms(200-300 ha) on the Mennonite coloniesand especially on the even smaller farmsof the Paraguayans who receive a regularincome from milk production. Milk pric-es are low due to competition from Argen-tina where the peso has been devalued,and profitability is further reduced by thehigh cost of concentrate feed. In the dryseason, milk quality (protein level) can beso low that the local cheese factories re-ject it. This is disastrous result for the smallfarmers could be lessened or preventedwith leucaena. Not only does it providefeed for the cattle but also the larger stemsprovide valuable fuel for cooking.

Steers in broadcastleucaena in the Chaco

10 TGS News

No psyllids seenI saw no evidence of any psyllid in ei-ther the western or eastern areas of Par-aguay. This may well be because the crit-ical area of leucaena plantings has not yetbeen reached, but leucaena has beenaround for a long time, particularly in thewetter eastern area of Paraguay. I didhowever see a caterpillar avidly feedingon the leaves and young shoots of a rap-idly growing stand of cv. Cunningham,and the farmer said he had to spray toprotect the new stand from heavy dam-age. It has been identified as a Spodopteraspp. Let us hope that this is just an iso-lated incident.An interesting development in this areawas the use, by cattlemen, of the skills ofcrop farmers to establish their leucaena.

Chaco salinity?

Dryland salinity could be a problem inparts of the Chaco as water tables riseafter the trees and shrubs have beencleared.Salt layers can be seen in places inroadside excavations and after a very wetyear, the vegetation has been killed bysalinity around some lagoons in theCentral Chaco. These outbreaks have notrecovered with return to the normalconditions.

Very good clearing guidelines have beenproposed (or legislated for) in thedevelopment of new ranches.Proportions of land that can be cleared

One excellent stand had been establishedby direct drilling into an old pasture of stargrass. The star grass had been killed with8 l/ha of ‘Roundup’ and the inter row are-as sown to soybeans (see photo). Contract-ing such skills should reduce the risk ofestablishment failures on predominantlycattle properties.

Pasture enthusiasmI thoroughly enjoyed my stay in Paraguay.It reminded me of the enthusiasm we ex-perienced in the early days of pasture im-provement using ‘new’ legumes andgrasses in Queensland. It was good to seemany of these species performing well inthe different environment of the Para-guayan Chaco. For leucaena, there certain-ly seems to be a bright future.

have been designated and salt-pronedepressions delineated on property plansusing aerial and satellite images.But on the smaller family blocks, muchland has been cleared for decades.Could planting deep-rooted leucaena beused to prevent further rising in the watertable?

This approach is being proposed by theLeucaena growers network in CentralQueensland—see the article on Leucaenafor control of salinity and water qualityin the Fitzroy Catchment on the next page.

Signs of salinity in the dry Chaco — dead trees around Captain’s Lagoon (left) and as the white foreground and white line at thebase of this roadside cutting (right).

TGS News 11

Dry land salinity is caused when risingwater tables bring salt from depth to thesoil surface. Water tables rise because achange in vegetation reduces the waterloss through transpiration.

The Fitzroy River catchment (142,600 sq.km) was once timbered with a mix of briga-low (Acacia harpophylla), softwood scrubsand eucalypt woodlands. In the 1960s and1970s, the fertile clay and duplex soils as-sociated with brigalow and softwoodscrubs were extensively cleared for pasturedevelopment and for cropping. Undercropping, good topsoil has bean lostthrough erosion, and soil fertility has rundown. An additional problem is that thesesoils have high salt levels at depth, and theloss of deep-rooted trees and scrubs meansthat dryland salinity could increase widely.

Replacing legume treesHow about replacing the lost original leg-ume trees with other legume trees? Theshallow-rooted brigalow with little produc-tive value could be replaced with leucae-na—deep-rooted, salt-tolerant and themost productive tropical cattle forage.Leucaena’s deep roots and high water-usecan prevent seepage of water through saltzones into ground water in recharge are-as. Vigorous leucaena-grass pastures re-duce runoff and erosion thus helping torestore water quality. The grasses also im-prove soil organic matter through their fineroot system while the legume improvessoil fertility through high nitrogen-fixation.

The leucaena-grass pastures offer one ofthe most productive animal productionsystems in the world, capable of cattle live-weight gains of 250-300 kg/head a year.

Major development proposalThe Leucaena Growers Network (with theguidance of Dr Max Shelton) is promotinga leucaena project for the control of salini-ty and water quality in the Fitzroy catch-ment; it is targeting areas that are margin-al for annual cropping and that have de-

graded grass pastures in high salinity-haz-ard zones. The regional target is 250,000hectares of leucaena over 7 years andwould involve some 800 growers plant-ing an average 100 ha per year.

Overall this proposal would:

improve catchment hydrology by pro-moting large-scale revegetation withthe deep-rooted tree, with associatedgrass ground cover, in key recharge ar-eas.

reduce deep drainage (affecting salini-sation) and run-off (affecting waterquality)

promote a technology that is realistic,underpinned by sound scientific un-derstanding and favourable cost-ben-efit analysis.

promote an integrated approach thatwill simultaneously strengthen eco-nomic, social and environmental out-comes.

add value to the principle economicactivity of the region (beefproduction).

Salinity saviour?

“Promoting the responsible development ofLeucaena as a productive and sustainable ecosystemto build stronger rural communities.”

“Leucaena—

the most highly

sustainable and

productive grazing

system for Northern

Australia.”

Large-scale leucaenaplanting could save salinity

12 TGS News

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