Although crop rotations with grain legumes and ley pastures play an important role in maintaining and improving soil fertility, fertilisers remain the major source of nutrients to replace those removed by grain production. The greater reliance on stored soil moisture for crop productivity in the clay soils of the northern region, rather than in-season rainfall, places a greater emphasis on subsoil nutrient reserves that can be accessed during periods when topsoils are dry. There are large gaps in our knowledge for many of the crops grown in the GRDC northern region, and for most of the nutrients, as well as the appropriate soil testing methodology to assess subsoil phosphorous (P), potassium (K) and sulfur (S) status.

The purpose of this project is to better understand plant responses to the supply of nutrients. With widespread regional trials, this work will provide soil test - plant response calibrations, focussing on P, K and S soil test-crop response information for sorghum, wheat and chickpea crops. The objective being to better match fertiliser inputs to meet crop demand yet minimise nutrient losses.