Ground Cover West : Ground Cover 066 January-February 2007 - West
take advantage of a variable climate. “Whether it’s climate change or normal fluctuations in rainfall, if we get more rain in summer than winter it’s absolutely essential to conserve that moisture. Having stubble on the surface allows good infiltration and conservation of that moisture and, provided you control summer weeds, you can seed earlier.” Dr Flower says the trials, sown from mid-May through to mid-June, showed that the earlier the crop was seeded, the better the returns. Mr Pearse, who started sowing his crops on 20 May, and who has seen his soil retain moisture from as little as a heavy dew, could not agree more: “It’s what our system is put in place for. With stubble retention to store all that summer rain, you’ve got moisture in the soil and you can seed into it without having to wait for rain. It’s so efficient in that regard.” More information: Dr Ken Flower, 08 9622 5584, 0427 000 729, firstname.lastname@example.org HORROR SEASON SHOWS WHAT IS POSSIBLE BY MELISSA MARINO n Colin Pearse made the switch to no-till farming 12 years ago. He was not a pioneer, he says; there were others no-tilling near his Meckering property in Western Australia. But he was certainly in early. “I’m one of those guys that if there’s something new then I’m really interested, andIliketohaveagoatit,”hesays. “We could see what these other guys were doing and it just made sense.” Mr Pearse has witnessed a lot of change on his 2630-hectare property since then. When he was a schoolboy, it was largely devoted to sheep, with about one-third of the arable area ploughed and cultivated for wheat and lupins. A move to continual cropping and a Sprayseed® system followed – spraying out weeds and seeding with full- cut points without ploughing or cultivating. From there, Mr Pearse says, their cropping percentage got higher and higher before they made the transition to where they are today: the no-till knifepoint system. Now, up to 85 per cent of the property’s arable 2020ha is in crop every year, with only areas unsuitable for cropping in pasture for sheep. Mr Pearse says it took four to six years for the no-till system to make a noticeable difference to their practice, which already incorporated stubble retention. But it was in 2006 that he feels the system really paid dividends. On less than 200 millimetres of growing- season rainfall, wheat yields were two to 2.5 tonnes per hectare, lupins 0.9 to1.7t/ha and canola 0.8 to 1.1t/ha. They are results that he says could not have been achieved under a conventional tillage system. “The changes we made were basically to become sustainable through the integration of chemical use in front of the no-till system; to integrate the use of trifluralin in the first place to help manage resistant weeds,” he says. “We then increased our organic matter, and through that and stubble retention, you almost eliminate wind and water erosion.” Mr Pearse persuaded his father Stan and brother Ross to embrace no-till, arguing the case for sustainability, and now he says they are converts. He believes that the yields they received in 2006 – the worst rainfall year in his experience – indicate their business is well set up for the future. “To a degree things have plateaued a bit, so I think from now on the changes are going to be small incremental things – the little ‘one-percenters’,” he says. “We’re looking more at our nutrients and fertilisers, and beyond that at cover cropping. “We’ve got to work out how we can fit cover crops into our system.” That calculation will be helped by the no-till system cover-crop trials funded by the GRDC and being undertaken on Mr Pearse’s property by the Western Australian No-Tillage Farmers Association (WANTFA). In the 2006 winter-sown cover-crop trials, Indian mustard returned biomass measurements after knife-rolling of 9t/ ha of dry mass, saia oats returned 11t/ha and grazing oats 9.5t/ha. Wheat trials also performed well, yielding two to 2.5t/ha under no-till with only 140mm of growing- season (May to October) rainfall and 176mm of summer rain. But WANTFA scientific officer and trial manager Ken Flower says the real story will be told in 2007, when wheat is sown into the cover crops. “If we get good summer rain, the thick mulch on the surface should help moisture retention,” he says. “There has been a suggestion that the thick saia oat mulch might impede the emergence of the wheat, but that’s something we will be looking into.” Dr Flower says the trials, due for completion in 2009, should be able to quantify the benefits of cover crops in wheatbelt no-till systems. These include more diversity in crop rotations, saving money on herbicides by reducing weeds and improving the yields of subsequent cash crops. “Lack of diversity is probably the main reason why we have the herbicide- resistance problems looming,” he says. Dr Flower says the 2006 season demonstrated that the no-till system was able to JANUARY -- FEBRUARY 2007 GROUND COVER 7 No-till KEY POINTS n 2006 showed the value of long-term no-till n Acceptable yields from worst-ever rainfall n Cover crops the next step (Left) Dr Ken Flower with wheat trials ready to be har vested last November. PHOTOS: EVAN COLLIS Established no-till practitioners in WA say the 2006 drought has raised the bar for sustainable cropping systems, with trials now under way to develop a winter-sown cover-crop regime to supplement no-till systems (Above) Colin Pearse credits the cumulative effects of 12 years of no-till for doubling what he would otherwise have yielded in the worst rainfall year in his experience.
Ground Cover 065 November-December 2006 - West
Ground Cover 067 March-April 2007 - West