Ground Cover Supplement : GC Supplement - Profitable pulses and pastures
both use desiccants, the former usually applies to longer-seasoned forage types, the latter on earlier-maturing grain types. Green and brown manuring incurs negative returns during the first year with no grain harvest. Therefore, a clear understanding of the benefits in subsequent years is required, particularly if similar results could be achieved from crop-topping and grain harvest. Brown manuring is the obvious strategy under heavy weed burdens and herbicide resistance. When grain is harvested, N benefits are reduced proportionally to the N removed in the grain. Anything affecting growth, such as disease, weeds, drought or sowing time, will directly reduce the N benefit. □ 14 Break crop and pasture options Mallee trials measure diversity impact The impact to following wheat yields is a factor in the overall value of a break crop By Dr Therese McBeath CAN GROWERS MANAGE the pressures on intensive cereal production in low-rainfall Mallee environments using break crops? This was the question tackled by CSIRO researchers and farming systems groups in the low-rainfall Mallee environment, with funding from the GRDC, where intensified cropping with heavy reliance on cereals has been considered to profitable option with manageable risk. However, the intensive use of cereals has put pressure on managing weeds, disease and nutrition. Growing legumes, canola or pasture as a break in continuous cereal cropping has been tested to help manage pressures on cereal production, but some of these breaks can be riskier and have a lower return than cereals. In collaboration with BCG and Mallee Sustainable Farming (MSF), WEIGH UP THE RISKS, BENEFITS OF PULSE HARVEST By Dr Eric Armstrong TO CROP-TOP, DESICCATE, harvest or manure? These strategic questions face all pulse growers and their decision is dictated by weed pressures, weed type and the nitrogen demands of the rotation. Supporting strategic management of pulses to maximise profitability in southern farming systems is the focus of a GRDC Pulse Agronomy project, 'Expanding the use of pulses in the southern region', and GRDC--Pulse Breeding Australia projects for breeding field peas, faba beans, lupins, chickpeas and lentils. The choice to include a pulse break crop is generally driven by the opportunity to add diversification into a crop rotation, biologically fix nitrogen (N) and tap into wider weed-control opportunities. While wheat and canola sequences are attractive in the short term, they invariably lead to a run-down of soil mineral nitrogen, increasing dependence on N fertiliser, increasing pressures from weeds and, eventually, herbicide resistance. Fertiliser N and herbicides do provide short-term solutions, but are costly, energy- hungry to manufacture, carry risks around availability and timing of application, and have long-term environmental implications. Used strategically, pulses can be a strong link in cropping regimes as a source of cheap and reliable N and a tool for managing weeds through green manuring, crop-topping, desiccation and good cultural practices. However, maximising the effect of cropping sequences relies on considerations such as: ¢ What is your main profit driver (to control weeds or maximise biologically fixed nitrogen)? ¢ What is the most profitable option for your business? ¢ Are you prepared to balance short-term economic gain against longer-term profitability, productivity and sustainability? Before choosing the best option remember: ¢ maximising biologically fixed nitrogen requires an understanding of the seasonal dry matter production curves of the crop and factors that affect or drive this; and ¢ the growth stage of the weed, growth stage of the pulse and choice of pulse crop and variety are critical when considering brown manuring, crop-topping and desiccation. There are many other considerations when deciding what to do with pulse crops. Brown manuring and crop-topping CSIRO researchers Dr Rick Llewellyn and Dr Therese McBeath (right) with trial host Hannah Loller. Hannah and her husband Peter grow lupins and canola for weed management, disease control and nitrogen fixation for the cereal program at their 2400ha property at Karoonda, South Australia. PHOTO: CSIRO PHOTO: ERIC ARMSTRONG When used strategically to control weeds, build soil nitrogen and conserve soil moisture, pulses become a strong link in the cropping rotation. Geoff McCallum, farm manager at Northparkes Mines, in a crop of brown-manured MorganA field peas.
GC Supplement - Climate forecasting
GC Supplement - Foliar fungal diseases of pulses