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Beyond the Bale : Oct 07 - Nov 07
By Nicole Baxter New research highlights the importance of precise seeding-depth control when sowing small-seeded, warm-season perennial pastures. Shallow sowing at five to 10 millimetres, but not surface seed placement, is critical for successful establishment of warm-season subtropical pastures, according to pasture researcher Ron Yates from the Department of Agriculture and Food, Western Australia. His work is part of a national project -- funded by AWI, Meat and Livestock Australia (MLA) and the Cooperative Research Centre for Plant-Based Management of Salinity (CRC Salinity) -- exploring best-bet establishment 'recipes' for a range of perennial pasture options being developed and promoted across southern Australia. Mr Yates says more producers in Western Australia's northern agricultural region and southern coastal districts are turning to warm-season perennials to deal with unpredictable climate patterns. But, until now, most have been left in the dark about the ideal seeding depth and have reported patchy establishment and the dominance of one or two species in mixed sowings. Mr Yates believes research from the project will endeavour to put some science behind what some producers have discovered through years of costly trial and error. "Obviously, low seed-quality will affect establishment, but our latest research shows if you sow too deep you will compromise seedling emergence," he says. In a small plot trial at South Perth, Mr Yates confirmed that precise sowing depths take some of the risk out of establishing warm-season perennials. His study looked at optimum seeding depths for five perennial grasses including Gatton panic, Katambora Rhodes grass, signal grass, Whittet kikuyu, Splenda setaria and the perennial legume Miles lotononis. During 2006, Mr Yates sowed 100 seeds in furrows on the surface and at depths of five, 10, 15, 20 and 30mm. In the trial, depth was precisely controlled using a wooden dowel with the seed sown by hand. The furrows were filled to the surface with sand and the seedlings counted weekly for four weeks. At five millimetres, Mr Yates discovered that most of the Rhodes grass and Miles lotononis emerged, but at 15mm or deeper very little emerged (see below). Likewise, most Gatton panic, Splenda setaria and Whittet kikuyu seed emerged at five to 10mm, but at 15 to 30mm there were large losses. For the large-seeded signal grass, there was little difference in emergence between five and 20mm, but losses appeared at 30mm. Surface-sown seed failed to establish, which surprised the researchers, although the seed was not pressed or rolled. "Given that most paddocks are sown to a pasture mix, a key finding is that a single-sowing depth of five to 10mm appears suitable for all the species studied," Mr Sowing depth critical for establishing perennial pastures A national AWI-supported study is developing reliable establishment packages for drought-tolerant native and exotic perennial species 18 PASTURES BEYOND THE BALE Yates says. "Farmers need to be precise with their sowing. If they sow seed at five to 10mm they will achieve a superior establishment." According to Mr Yates, sowing practices for warm- season perennials are improving in WA year by year, particularly from the support and expertise provided by the Evergreen Farming group, also supported by AWI. Trials carried out during 2007 will refine sowing recommendations for farmers by examining the performance of a range of tine, points and seed-delivering systems. "In deep sands, results show seedling emergence is best with wider points as non-wetting soil is displaced away from the sown seed and there is less chance of sand collapse from the furrow edges," Mr Yates says. "The project is getting great assistance from Dr Chris Loo from the Kings Parks Botanic Gardens and Parks Authority, who is investigating increasing germination though chemical priming, seed coating and other seed treatments. "Following further experiments we should have more information on how these seed treatments can be combined with better agronomic practices to further refine reliable establishment procedures for a wide range of pasture species, including forage shrubs and native grasses across southern Australia." ú More information: Ron Yates, 08 9368 3665, 0427 550 125, firstname.lastname@example.org Department of Agriculture and Food,Western Australia, pasture researcher Ron Yates inspects 2007 sowings at a trial site near Gillingarra,WA. Lotononis seedlings did not germinate when sown on the surface (left) or at a depth of 30mm (middle), but displayed excellent establishment when sown at a depth of 10mm (right). PHOTOS: DAFWA
Aug 07 - Sep 07 Supplement
Dec - Jan 08