Reaping Rewards
Making use of EM mapping in the Mallee
Reaping Rewards was a three year project (2006 – 2008) funded by GRDC. The project was a collaboration between CSIRO, Mallee Focus and Mallee Sustainable Farming Inc.
Objective
The major objective of the Reaping Rewards project was to develop the practical application of EM38 as a low-cost reliable tool to assist soil-specific management for more cost-effective and lower-risk input use on Mallee soils.
Background
The Reaping Rewards project was developed to follow on from earlier MSF-CSIRO research focused on intensive cropping and help farmers across the Mallee region of SA, Vic and NSW better manage high cropping input costs, risk and variable soil types. The project worked closely with growers and agri-business to develop the use of EM38 mapping as a reliable, practical and low-cost tool for mapping Mallee soils and subsequent site-specific management of paddock zones. Prior to the Reaping Rewards project there was little use of EM38 on a commercial farm basis. To achieve widespread practical use it was identified early in the project that there was a need to test EM38 mapping in terms of its ability to be used post-harvest when the soil is relatively dry (most existing applications of EM mapping recommended wet soil profiles) and its reliability in mapping relatively stable important drivers of production potential. The profitability of applying variable rate fertilizer to identified paddock zones also needed to be demonstrated and tested over the short and long-term.
Research
Using focus paddocks and over 40 mapped and characterised field sites, the research demonstrated the ability of EM mapping of dry Mallee soils to be used as a stable base information layer, highly correlated to subsoil constraints (e.g. EC1:5) and plant unavailable water. In addition to field site results, APSIM (Agricultural Productions Systems sIMulator) to test the performance of variable rate N applications on the EM-based zones under a long-term range of growing season scenarios. This work also led to the development of the MSF N-Tool, a decision support tool designed for variable rate fertiliser allocation decisions on Mallee soils. Other aspects of the Reaping Rewards project have included analyses of the biological sustainability of intensive cropping systems based on the long-term core trials
Outcomes
EM38 is now recognised as a particularly useful tool for Mallee soils as it typically correlates well with important 'fixed' soil characteristics that are associated with crop yield potential e.g. salt related subsoil constraints that reduce plant available water (PAW). Stimulated by increased fertiliser prices, more agronomy service providers using EM mapping and reduced EM mapping costs, the uptake has been rapid. The area of EM mapping increased from an estimated 20,000ha to 180,000ha over the life of the project and many whole farms are now being EM mapped, with several agronomy service providers incorporating the use of EM mapping into their agronomy services to growers. The use of variable rate inputs on paddock zones is now a common practice with the Mallee having one of the highest adoption rates in Australia.
Implications
Targeting inputs according to the production potential and riskiness of well understood soil-based zones gives Mallee farmers a greater ability to increase the rate of return from inputs and manage the risk associated with seasonal and soil variability in a low rainfall environment. As more land is mapped, including many whole farms, new opportunities for economic and environmental benefits are becoming apparent.
More information is available on this website
farmtalk no 23 – Making use of EM in the Mallee
MSF 2008 Compendium
The N Tool is available from Mallee Focus
Further information
The role of EM mapping in precision agriculture in the Mallee.
Rick Llewellyn, Anthony Whitbread, Ben Jones and Bill Davoren
Proceedings of the 14th Australian Agronomy Conference, Australian Society of Agronomy, Adelaide, 2008
www.regional.org.au/au/asa/2008/concurrent/managing-site-season/5915_llewellynrl.htm
Long-term performance of intensive cereal-based cropping in the Mallee.
Bill Davoren, Gupta Vadakattu and David Roget
.Proceedings of the 14th Australian Agronomy Conference, Australian Society of Agronomy, Adelaide, 2008
http://www.regional.org.au/au/asa/2008/poster/farmer-focussed-research/5844_davoren.htm
EM38 and crop-soil simulation modelling can identify differences in potential crop performance on typical soil zones in the Mallee.
Anthony Whitbread, Rick Llewellyn, D Gobbett and Bill Davoren
Proceedings of the 14th Australian Agronomy Conference, Australian Society of Agronomy, Adelaide, 2008
http://www.regional.org.au/au/asa/2008/poster/agronomy-landscape/5823_whitbread.htm
Farming system impacts on microbial activity and soil organic matter dynamics in southern Australian Mallee soils.
Gupta Vadakattu, David Roget, Bill Davoren, Rick Llewellyn and Anthony Whitbread
Proceedings of the 14th Australian Agronomy Conference, Australian Society of Agronomy, Adelaide, 2008
http://www.regional.org.au/au/asa/2008/concurrent/crop-agronomy/5918_guptavvsr.htm
| 
