Ground Cover South : Ground Cover 047 November-December 2003 - South
By ALEC NICOL A trial in which perennial grasses have been grown in rotation with wheat crops in southern NSW has produced some promising -- and surprising -- results. Early indications suggest that perennial grasses are a viable alternative to lucerne for drying the soil profile and reducing deep drainage. Trials by Dr Brian Dear from Wagga Wagga Agricultural Research Institute show that three or four years of pasture containing phalaris, or a similar perennial, will result in a dry buffer zone between topsoil and the water table for about five years. However, there are obvious drawbacks. Unlike subclover or lucerne they do not fix nitrogen, they may starve a following crop of moisture, and there is the loss of the disease buffer. After harvesting wheat crops in 1999 and 2000 at two sites in the southern grain belt where perennial grasses had been part of a three or four-year pasture phase, Dr Dear says the yields compared favourably with those following subclover. He says protein levels may be down a touch but will still make an Australian Hard grade. However, he says timing the removal of the pasture prior to cropping, and getting the pasture mix is very important. Dr Dear's two sites were at Ardlethan, annual rainfall 430mm, and Junee where the average is 550mm. He used phalaris, cocksfoot, wallaby grass, and lovegrass in mixtures with subclover and lucerne, and compared the results with a clean subclover pasture and one with the usual annual volunteers. He sprayed the pastures out in late August and November in the year prior to sowing at Ardlethan, and in early September and November at Junee. Early removal pushed yield up almost half a tonne per hectare at Ardlethan, but this only marginally improved yield at the wetter Junee site. Yields varied between 6.6t/ha to more than 7t/ha at Junee and from 3.6t/ha to just over 5t/ha at Ardlethan. Removing the pasture early increases the moisture available to the crop through the growing season. This was critical at Ardlethan where the crops stayed greener longer and flowered later and suggests to Dr Dear that, in dry conditions, getting the mix of perennial and annual pasture is crucial. He noted that annual subclover did not compete well with the perennial grasses; however this appears to be overcome by dropping grass density from 40 plants per square metre to around 10 plants. Dr Dear says the biggest surprise was the lack of take-all in the crops following the grass pastures. There was no evidence of it and overall his yields matched the best in the district. A preliminary examination by plant pathologist Dr Gordon Murray has not found any increase in the pathogen in the soil. Another unexpected benefit seems to be the capacity of perennial grass to control nuisance weeds such as vulpia and stink grass, plus phalaris provided valuable winter feed. All of the grasses provided better year-round ground cover than either lucerne or subclover. "We always knew that perennial grasses could do the job when it came to managing drainage. Now we have the basis of managing them in a rotation," says Dr Dear. GRDC RESEARCH CODE CSP291 For more information: Dr Brian Dear: Ph 02 6938 1999 RESEARCH UPDATE 9 NOVEMBER 2003 All of the grasses provided better year-round cover than either lucerne or subclover. New Engines! More Power! New Transmissions! Better Economy! Same Versatile Dependability 2290 290 Horsepower 2335 335 Horsepower 2375 375 Horsepower 2425 425 Horsepower FROM AS LOW AS 5.9% AVAILABLE *Normal credit criteria & some conditions apply. 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Perennial grasses emerge as a rival to lucerne Eureka Prize: science wakes up to old knowledge Perennial native grasses that produce a millable seed -- and have been a part of Australia's indigenous food supply for thousands of years -- are now regarded as a potential new, hardy, crop for land damaged by erosion and salinity. Research into these perennial native grasses, which may prove to be ideal for soils prone to land degradation, won this year's Eureka Prize for Research to Improve the Environmental Sustainability of Graingrowing. The $10,000 prize is sponsored by the GRDC. The award-winning researchers, Dr Ted Lefroy, from CSIRO Sustainable Ecosystems in Perth, and Dr Christine Davies and Mr David Waugh, from the University of Western Australia, have already started selection trials for several native grasses. In looking for high seed yield, large seed size and an erect, short stalk, the researchers identified one particularly promising variety of weeping grass, Microlaena stipoides. The research is considered radical for agriculture because for 10,000 years grain production has relied on annual grasses such as wheat and barley. However the three researchers believe domesticated perennial Australian grasses will be commercially viable and environmentally sustainable for grain production and grazing. Dr Lefroy says perennial grasses can harness rainfall throughout the year, making them well suited to areas with poor soils and unreliable seasonal rain: "Additionally, native grasses may be better able to manage dryland salinity." Dr Lefroy says there is no intention to try and replace wheat and barley, but to offer a cropping alternative for land that is marginal, prone to erosion, or loses a lot of its water. The director of the Australian Museum, which sponsors the Eureka Prizes, Professor Mike Archer, says the research could produce important outcomes for Australia. "You could argue that these researchers are flying in the face of evolution: annual grasses have a strong evolutionary incentive to produce big seeds, perennials don't -- they put more effort into roots and foliage," he says. "But perennials could be the answer in Australia. If successful, this research could help change the face of agriculture and the Australian landscape."
Ground Cover 048 February-March 2004 - South