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Beyond the Bale : Feb 07 - Mar 07
7 PASTURES BEYOND THE BALE Australian native perennial Rhagodia. PHOTO: TIM WILEY Australian mixed-forage systems based on the resilience of native shrub species. "We are not trying to recreate native bush, but rather use it as a template for forage systems that can remain green year-round and tolerate conditions that challenge more traditional annual pastures and crops," says Dr Dean Revell, the CSIRO Livestock Industries senior scientist who is leading the project. "However, the ability to provide valuable feed in dry seasons is not the sole benefit of these forage shrubs. According to some recent economic modelling, forage shrubs on a modest area of the farm are capable of improving whole-farm profitability in average years, besides reducing risk due to seasonal variation." Benefits to farmers are being maximised by deliberately designing plant mixtures that can deliver animal health and improved land-management outcomes, which in turn help lower input costs. On the downside, Dr Revell says people tend to associate diverse plant mixtures with greater management complexity. "The concept of mixed pastures is well understood so the task of Enrich is to solve the obstacles to implementation. We need to know which species to plant, in what combinations, where on the farm and how to graze them." Under the umbrella of Enrich, parallel research activities are under way that collectively could deliver mixed forages to the southern livestock-cropping zone. Researchers are all linked through the Cooperative Research Centre for Plant- based Management of Dryland Salinity (CRC Salinity) and the assay's sensitivity means that benchmarks for optimum root performance may be established for different pasture management strategies such as grazing, fertiliser and chemical applications, and also recovery from stress." Dr Hannam is confident that a better understanding of microbe--root interactions can also serve as a platform for developing techniques to influence the behaviour of roots and microbes. An Australian National University basic science study is focusing on how soil bacteria near roots emit chemical signals (quorum sensing signals) to influence the bacteria's behaviour, and how plants respond to these chemicals. Pasture species such as subclover, barrel medic and ryegrass have been shown to respond through accelerated germination, altered plant growth and changes in the interaction of the plants with soil bacteria. "Once these processes are understood, it is conceivable that special signalling compounds could be used to stimulate plants to better fight fungal pathogens and other pathogenic soil-borne organisms," he says. "There is also evidence that plants can detect the bacteria's chemical signals, which may help the plant prepare defensive responses to infection or emit 'mimic' chemicals to confuse the bacteria behaviour.This opens up the opportunity to breed plants for the ability to secrete compounds that can influence the behaviour of soil bacteria near the root surface." In another study, CSIRO Plant Industry is looking at the interaction between soil pathogens and the environment surrounding the roots (the rhizosphere). They are determining how plant roots respond to stress and how this influences microbe colonisation of the rhizosphere. "The Pasture Soil Biology Program was recently subject to external review by a team of scientists who strongly recommended that the overall research program is sound and should be continued," Dr Hannam says. "We look forward to continuing to develop and validate a comprehensive suite of molecular assays in association with targeted basic science on understanding the interactions between roots and soil biota at the root surface." The program is jointly supported by AWI, Meat and Livestock Australia (MLA) and the Grains Research and Development Corporation (GRDC). Dr Hannam is inviting other research investors to join the next phase of research to ensure "a strong collaborative funding base" that can foster investment in frontier research of wide interest to farmers and with potential benefit for soil health and productivity. -- GIO BRAIDOTTI More information: Dr Bob Hannam, email@example.com are based at CSIRO Livestock Industries, the University of Western Australia, DAFWA, SARDI, the NSW Department of Primary Industries and the South Australian Department of Water, Land and Biodiversity Conservation. Over three years, the researchers are looking to: ú propagate and test under field conditions the forage potential of about 100 native shrub species at a research site in Monarto in SA; ú measure the shrubs' nutritional value; ú test the same plant material for bioactive compounds that can affect rumen health and control gut parasites; ú establish a field site at Badgingarra, WA, with six shrub species and some perennial grasses that can be further sown with annual pasture species in the 2007 season to provide a test grazing site to look at grazing behaviour and ways to modify it; ú complete face-to-face surveys with farmers in WA, SA, Victoria and NSW who have experience with shrubs; and ú perform economic modelling using different establishment costs and different productivity levels to help understand the factors that can optimise whole- farm profitability. Crucial to the shift away from monoculture is the idea that growers can use livestock directly to help manage the extra complexity. This can seem like a 'wacky' idea, but Dr Revell has visited the US where it is already being successfully put into practice. "Animals can be better than us at making informed decisions about what to eat and when to eat it," he says. "We've done our best to supposedly simplify systems and pastures, but there is a lot of exciting research worldwide saying animals can manage decisions about different plant species that are complementary for nutritional and health values, particularly gut and rumen health, even reduced worm parasite loads." The trick is to provide livestock with the right experiences of all of the plants in the mixture and then rely on their learnt grazing behaviour. As to the polycultures themselves, they stand to offer greater flexibility and resilience to a farm by strengthening the ability to respond to environmental and economic pressure. "Australia's rural landscape can pose tough challenges for farmers even at the best of times but many current problems -- like dryland salinity, susceptibility to drought, and soil erosion -- stem from the replacement of native perennial vegetation with annual crops and pastures," Dr Revell says. "This means that perennial forage systems offer prospects for managing many of these issues and Enrich is about gaining the experience growers need to benefit from a perennial feedbase." The Enrich Project will run until June 2008 with researchers hoping to host field days as early as 2007 at the SA and WA sites. The project is funded by AWI, Meat and Livestock Australia, the Rural Industries Research and Development Corporation and the CRC Salinity. ú More information: Dr Dean Revell, firstname.lastname@example.org (Far left) Dr Dean Revell, senior research scientist with CSIRO Livestock Industries, examines some saltbush. PHOTO: EVAN COLLIS
Feb 07 - Mar 07 Supplement
Dec 06 - Jan 07