Jessica Crettenden (SARDI)
|Contributor||SARDI Minnipa Agricultural Centre|
Site 17, Minnipa Agricultural Centre, SA
Mixed livestock and cropping systems have an important role to play in the diversification, risk management and sustainability of farming in low rainfall areas. The majority of farms in these areas use livestock to provide enterprise diversity and risk management, however grazing also offers a range of other system benefits that are generally not accounted for in mixed farming enterprises. As a result of increasing cropping intensity in these systems, there is a perception of declining productivity of the pasture phase, with pastures remaining largely unimproved and most farming systems continuing to rely on self-regenerating medic for livestock feed and nitrogen (N).
Pastures in these lower input mixed farming systems are generally set stocked and grazed at low stocking rates throughout the season with minimal effort to manage grazing for optimal production. Farmers are hesitant to increase grazing in the break phase of the rotation partly due to the perception that livestock can damage soil health, remove organic matter and induce weed germination, but also because their efforts are often concentrated on the cropping enterprise due to the income it brings into the business. With prices for livestock (both meat and wool) increasing over the past decade, and the valuable nutrition and disease break effect that the pasture phase provides to subsequent cereal crops, interest in the productivity and profitability of medic and livestock systems has increased.
A long-term study was established at the Minnipa Agricultural Centre from 2008 to 2016 (EPFS Summaries 2008 to 2015) to assess the systems impact of grazing on crop and pasture production, and soil health. The nine-year broad acre demonstration with a wheat-medic rotation (Table 1) also tested whether productivity could be improved under a higher input system (e.g. higher fertiliser and seeding rates, establishment of improved pasture) compared to a lower input and more traditional system (district practice seed and fertiliser inputs, volunteer pasture), and what effect this had on soil fertility.
|Lead research organisation||
Southern Farming Systems
|Host research organisation||
SARDI Minnipa Agricultural Centre
|Trial funding source||GRDC SFS00028|
Grain & Graze 3
I gratefully acknowledge the help of Jake Hull, Wade Shepperd and John Kelsh for site management and Ian Richter, Sue Budarick and Brett Hay for data collection. I would also like to thank Barry Mudge with his assistance in the basic economic analysis of the trial. The Eyre Peninsula Grain and Graze 3 project is funded by GRDC (SFS00028).
|Other trial partners||Participating organisations: EP, BCG, MSF, Ag Excellence Alliance.|
|Sow date||Not specified|
|Harvest date||Not specified|
|Plot size||100m x 350m|
||Gross margin low input (ungrazed) ($/ha)||Gross margin high input (ungrazed) ($/ha)||Gross margin low input (grazed) ($/ha)||Gross margin high input (grazed) ($/ha)|
|1||█ 2008 wheat||-49||-42||-49||-42|
|2||█ 2009 wheat||829||879||803||905|
|3||█ 2010 medic||-23||-39||96||284|
|4||█ 2011 wheat||284||366||362||465|
|5||█ 2012 medic||-27||-27||26||89|
|6||█ 2013 wheat||332||390||356||464|
|7||█ 2014 wheat||525||677||598||749|
|8||█ 2015 medic||-15||-60||86||151|
|9||█ 2016 wheat||339||490||372||490|
|Rainfall avg ann (mm)||325mm|
|Rainfall avg gsr (mm)||241mm|
|Rainfall trial total (mm)||391mm|
|Rainfall trial gsr (mm)||268mm|
SILO weather estimates sourced from https://www.longpaddock.qld.gov.au/silo/
Jeffrey, S.J., Carter, J.O., Moodie, K.B. and Beswick, A.R. (2001). Using spatial interpolation to construct a comprehensive archive of Australian climate data , Environmental Modelling and Software, Vol 16/4, pp 309-330. DOI: 10.1016/S1364-8152(01)00008-1.