Background

This five-year National Risk Management Initiative (2023 – 28) aims to understand and improve the risk-reward outcomes for Australian grain growers by supporting grower on-farm decision-making. The project will take a Participatory Action Research (PAR) approach involving a network of 26 grower groups, 10 research partners, and 6 research group leads nation-wide.

The GGA will collaborate with the Grains Research Development Corporation (GRDC), and CSIRO, as well as 8 Western Australian grower group project partners including, Stirlings to Coast Farmers, South-East Premium Wheat Growers Association (SEPWA), Facey Group, Corrigin Farm Improvement Group (CFIG), Western Australian No-Tillage Farmers Association (WANTFA), Liebe Group, West Midlands Group (WMG), and Mingenew Irwin Group (MIG)

SCF Project

This project investigates how crop rotation influences nitrogen use efficiency (NUE), emissions intensity, profitability, and grower risk behaviour in the high rainfall zone (HRZ) of Western Australia. Cropping systems in this region are largely conducted on sandy duplex soils with inherently low water- and nutrient-holding capacity, creating a production environment that differs markedly from higher-performing systems in eastern Australia. These soil characteristics, combined with frequent high rainfall events, increase the leaching and denitrification losses of applied nitrogen. Alongside this, low NUE where a relatively small proportion of applied nitrogen is recovered in grain yield or grain protein, has contributed to the yield gap seen in HRZ. As a result, many growers adopt conservative nitrogen strategies, particularly in higher rainfall seasons when losses are perceived to be greatest.

Local soils are highly prone to leaching and short-term waterlogging, which has led to limited confidence in soil nitrogen banking. Consequently, nitrogen decisions are often made on a seasonal or ‘set-and-forget’ basis. This approach can result in over-application in low decile years and insufficient nitrogen supply when seasonal conditions favour high yield potential.

In response to this challenge, Stirlings to Coast Farmers established a long-term field experiment in 2023 to assess both agronomic and economic outcomes of differing crop rotations and nitrogen risk strategies. Alongside the field measurements, APSIM modelling and emissions calculations are being used to extend the relevance of the trial results across a broader range of seasonal and management scenarios. The overall aim is to quantify both the risks (lower NUE and higher emissions intensity) and rewards (profitability and yield stability) associated with different nitrogen strategies and rotational sequences in the WA HRZ. By providing robust, regionally relevant data, this project seeks to improve grower confidence and support more adaptive nitrogen decision-making.