Phosphorus and potassium


Developing new methods and indicators to characterise the availability of phosphorus (P) and potassium (K) for field crops.

Against a background of growing scarcity of fossil phosphorus (P) resources and the risk of degradation of surface waters through eutrophication as a result of the transfer of P from soils, the management of phosphate fertilisation of agricultural crops is one of today’s burning issues. In Switzerland, the rationale for phosphate fertilisation is essentially based on the evaluation of the amount of P available for the plants, arrived at by chemical extraction. Given the poor predictive value of chemical extractions, however, this diagnosis remains imprecise and unreliable. Substantive advances in identifying and evaluating the available soil P fractions have been obtained via the quantitative and hierarchical analysis of the contribution of potential mechanisms for mobilisation of P by the roots. In this context, the research carried out as part of a number of projects by  Agroscope’s ‘Plant Nutrition’ team in partnership with other institutions outside of Switzerland will furnish indispensable information for improving the phosphate fertilisation practices of Swiss agrosystems.