A comprehensive technical report explores the yield gap typical in commercial wheat and canola crops in the high rainfall zone (HRZ) of southern Australia. A previous report concluded that the yield gap was due to insufficient fertiliser being applied to achieve potential yield. The main barrier to supplying sufficient nutrients was identified as a lack of confidence that higher fertiliser rates would result in an economic return on investment.
The new report highlights progress and provides an overview of the nutrient status of phosphorus (P), potassium (K), nitrogen (N), sulfur (S), copper (Cu) and zinc (Zn) in both the soils and wheat and canola crops in the HRZ of south-eastern Australia. Growers and advisors will be offered assistance in making decisions on nutrient applications to maximise the economic yield potential of wheat and canola.
Research behind this report includes:
- Nutrient omission trials to test the response of wheat and canola to N, P, K, S, Cu and Zn.
- A survey of nutrient status using soil, grain and plant tissue samples collected from farm paddocks to determine actual status relative to critical values in the scientific literature.
- Simulations using a process-level model of wheat and canola growth examined potential N responsiveness in different rainfall scenarios and provided reliable estimates of the grain yield response of crops.
- A review of existing decision support tools that showed how the preliminary process-based crop model can be used to examine the profitability and risks associated with single-input usage (N or P, other nutrients not limiting) under a variable climate. This will be extended to examine more realistic situations that simultaneously examines multi-variable input response processes (such as N and P or S or K) on wheat and canola yields.
The research project concludes after the 2017 growing season and will use the final year to test the consistency of field findings across seasons.