Extensive research has focussed on demonstrating the quantum of crop responses with different crop species at different nutrient addition rates in soils with varying subsoil phosphorous (P) and potassium (K) status. In contrast, little research has been conducted to optimise product choice, application strategy and product compatibility when nutrients are co-located. The current project addresses this knowledge gap in the GRDC Northern grains region by using a combination of field, glasshouse, and laboratory studies to develop comprehensive deep nutrient placement guidelines for growers.

These guidelines will identify the most effective fertiliser product and form to overcome a specific subsoil constraint and maximize crop responses - both in the target crop and as a residual benefit in subsequent crop seasons. It will also explore the impact of fertiliser application method (tines, discs, zonal tillage, direct high pressure injection) on crop recovery, with key trade-offs involving the amount of soil disturbance and potential moisture loss/seed bed roughness with the volume of nutrient enrichment, the cost of ground-engaging equipment, horsepower requirements and reliability of performance under different moisture conditions and soil types.