Wheat and Lupin Potassium Responses

Assessment of soil test and K responses for wheat and canola in southern Victoria.


01 Dec 2013

Potassium response curves

The Better Fertilizer Decisions for Crops Project (BFDC) that concluded in 2012 identified several gaps in data around the development of robust soil test calibrations. This project seeks to collect crop responses to applied potassium particularly from the high rainfall zone of southeastern Australia. This region has a high yield potential and in general soil K values are low, and as cropping expands it seems reasonable to conclude that K nutrition will become a significant component in a nutrient management plan.

The project will follow standard protocols - largely developed from the BFDC project - to establish response experiments to help fill the current knowledge gaps.

Soil samples will be taken 0-10 cm, 10-20 cm and 20-30 cm for K response curves. Colwell K, exchangable K and tetraphenyl borate K extractions will be undertaken, along with some estimates of clay mineralogy using hand held gamma radiometrics (where appropriate).

Nutrients will be applied as KCl at 4 rates with basal N, P and S treatments. Each experiment will have four replications. Sites will be selected using the above soil tests and local knowledge of potentially responsive sites.

Target crops will be wheat and canola initially.

Crop growth, yield and quality will be assessed and responses fitted using the protocols developed in the BFDC project. All data will be included in the national database of soil fertility responses.