Exchangeable or non-exchangeable K - that is the question

Lighting a flare for magnesium

Saving money or saving costs?

4 decades of K Proceedings

Modelling offers the best prospect for improving our understanding of the dynamic interactions between the soil supply of K and crop demand for K, claims Professor Keith Syers of the University of Newcastle upon Tyne, UK, in Proceedings No. 411 “Soil and Plant Potassium in Agriculture” of the Fertiliser Society. Fertilizer recommendations for K are being modified in the light of greatly increased crop offtake in recent years but, although there have been advances in modelling the uptake of K by crops, there is still a shortage of data to validate the models. For widespread acceptance at the field level, models require a better integration between the soil and crop components, simplification and validation.

Of particular interest is the relationship between “slowly available” K and initially exchangeable K in soils where mineralogical composition is known. This is because it may be possible to moderate exchangeable K values, based on an estimate of the supply of slowly available K, in order to develop more precise fertilizer recommendations.