Optimising the yield and economic potential of high input cropping systems in the High Rainfall Zone

The High Rainfall Zone in southeastern Australia has high yield potentials for wheat and canola, but growers are faced with challenges about resource allocation in a relatively new and rapidly evolving cropping system. This project will develop tools that predict the production and economic response as well as the risks associated with applying the level of inputs needed for wheat and canola crops to achieve their potential in this region.


22 May 2017

2016 Annual Interpretive Summary

Canola and wheat grain yields in the high rainfall zone of southern Australia are currently less than half of the predicted potential. The main barrier to achieving these potential yields is the application of sufficient nutrients. There has been limited research on nutrient response of crops to soil nutrient status, conducted in this humid region. It was hypothesized that grain yields in the southeast of South Australia would be limited at soil test levels higher than those currently accepted, as the current critical soil test levels are based on response studies undertaken in regions of lower yield potential. Nutrient omission experiments were undertaken with wheat and canola to assess the impact of particular nutrients on yield under different rates of nitrogen (N) supply. A decile 10 season (high rainfall season) in 2016 saw grain yield responses to phosphorus (P) and sulfur (S) of 17 to 38% over an unfertilized control, where N was applied met the expected yield potential.

Across the sites tested, the limiting nutrients were first N, followed by P and S. Relative to the 2016 site and season, the current critical values were suitable for P in wheat and S in canola, but too low for P in canola and S in wheat. A decile 1 season (low rainfall season)in 2015 did not allow full expression of the yield potential achievable in most seasons in this region, with only an N response observed in canola. Further evidence is required to substantiate these findings in less extreme seasons.