Biomass, feed quality, mineral concentration and grain yield responses to potassium fertiliser of dual-purpose crops

The effect of increasing rates of potassium (K) fertiliser was studied on a soil with base exchangeable K values <= 0.1 cmol(+)/ kg by assessing biomass, feed quality, mineral concentration and grain yield for wheat, triticale and canola. The crops showed variable biomass response to K rates at early plant growth stages, however at anthesis there were significant positive biomass responses to increasing rates of K. A positive K rate effect was detected on feed quality with significant increases in metabolisable energy. Irrespective of sampling time, increasing K rate resulted in significant increases in crop K concentration and mineral ratios, such as the Tetany index, but significant decreases in Ca and Mg concentrations. Final grain yield was significantly increased by K rate and there were beneficial effects on grain quality (thousand grain weight). Overall, this study highlights the importance of K to production responses and implications for the health and productivity of grazing livestock.