Ground Cover Supplement : GC Supplement - Integration of livestock cropping
4 Issue 129 | July -- August 2017 | GRDC GROUNDCOVERTM SUPPLEMENT GROUNDCOVER GRAZING CROPS Sow early and graze early to maximise whole- farm profit By Philip Barrett-Lennard n Over the past decade, mixed farmers in Western Australia have increasingly embraced crop grazing as a tool to improve livestock productivity and whole-farm profitability. However, with much of the information initially based on research and experience from eastern Australia there were concerns about the impact on crop yields in the WA environment. In most crop-grazing trials in WA, grazing reduced crop yield. While crop grazing can improve whole-farm profits, in many cases growers simply swapped cropping income for livestock income. Growers hoping to adopt crop grazing need to look at how the whole farming system needs to be adapted. Without these changes, whole-farm profit is likely to remain unchanged, or even decline, as too much crop income is sacrificed in the pursuit of additional livestock income. The keys to improving whole-farm profits through crop grazing are to: n sow crops early to provide crop biomass for grazing in late autumn and early winter when pasture is scarce; n minimise grain yield penalties from overgrazing; n run a higher livestock stocking rate; and n graze crops with an economically responsive class of livestock. SOW EARLY Sowing crops destined for grazing early has a huge impact on the amount of biomass available for grazing in late autumn and early winter. In most seasons, mixed farms in WA suffer from a feed shortage in late autumn and early winter. Supplementary feed, such as grain and Digestibility (metabolisable energy) is the main factor that determines feed intake. Sheep will eat the most digestible feed first (grain and green) and leave the least digestible (straw and trash) until last. A feed needs more than 7.4 megajoules of metabolisable energy per kilogram of dry matter (DM) for weight gain. Protein is also important for growth and lactation, with levels above 12 per cent required. These levels are only found in green shoots and grain (Table 1). To estimate the quantity of useful feed from cereal stubbles, count the number of grains and green shoots in a 0.1 metre square (32 x 32 centimetres) quadrat (see Figure 1 and Table 2). For other grains, the number of grains counted per 0.1m2 that equate to 100kgha is: lupins -- eight, field peas and chickpeas -- five, and faba beans -- two. GROUND COVER Maintaining adequate ground cover is critical in lower-rainfall environments. A minimum of 50 to 70 per cent ground cover (about 1.0 to 1.5 tonnes of DM/ha) must remain on paddocks to prevent wind erosion, with standing, anchored stubble 10cm high is twice as effective at reducing wind erosion as loose flat stubble. o GRDC Research Code SFS00028 More information: Alison Frischke, 0429 922 787, firstname.lastname@example.org; www.grainandgraze3.com.au/resources/ Stubble%20assessment%20tool.pdf * Conducted by Southern Farming Systems, Birchip Cropping Group, Eyre Peninsula Agricultural Research Foundation and Ag Excellence Alliance. Stubble quality can vary between crops and seasons due to improved harvest efficiency and weed control, and can change quickly across a paddock, particularly once grazing begins or after summer rain.
GC Supplement - Weeds