Ground Cover Supplement : GC Supplement - Grain and Graze
15 Grazing on cropped land by Philip barrett-lennard WINTER CROP EXPANSION GIVES OPTIONS IN NORTHERN WA WHEATBELT IN AN IRONIC twist, drought has stimulated some farmers in the northern wheatbelt of Western Australia to increase rather than decrease the area they are sowing to winter crops. The aim is to reduce production risk by sowing a greater crop area but reducing upfront inputs and therefore costs. As drought stimulates crop expansion the season unfolds the growers make tactical decisions about further inputs (for example, nitrogen and post-emergent weed control) and whether to graze some crops. If the early winter rains are sufficient then annual pasture paddocks will produce enough feed, making it unnecessary to graze crops, which are then taken through to harvest ungrazed. However, if early rains are poor, some of the cropped paddocks can be grazed to ensure there is enough feed for livestock without additional hand feeding. The timing and duration of grazing is flexible. A single light grazing in the tillering-to-stem-elongation phase will not reduce grain yield and can even increase yield in a dry year as there is less leaf canopy in winter and so more soil moisture remaining for grain fill in spring. If the season turns into a true drought then livestock continue to graze the worst of the crops, which would otherwise have failed, for the remainder of the season. The grazed crops also provide better protection from wind erosion over the following summer than volunteer pastures. □ Impact of grazing on canola yield at Woogenellup, Western Australia. Grazing (left) for 10 days from 27 July at 24 dry sheep equivalent (DSE) grazing days per hectare reduced canola yield by eight per cent compared with ungrazed plots (right) but delivered 241 DSE grazing days/ha to the farming system.
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