Processes governing phosphorus availability in temperate soils

Phosphorus losses from agricultural soil to water bodies are mainly related to the excessive accumulation of available P in soil as a result of long-t erm inputs of fertilizer P. Since P is a nonrenewable resource, there is a need to develop agricultural systems based on maximum P use efficiency with minimal adverse environmental impacts. This requires detailed understandin g of the processes that govern the availability of P in soil, and this pape r reviews recent advances in this field. The first part of the review is de dicated to the understanding of processes governing inorganic P release fro m the solid phase to the soil solution and its measurement using two dynami c approaches: isotope exchange kinetics and desorption of inorganic P with an infinite sink. The second part deals with biologically driven processes. Improved understanding of the abiotic and biotic processes involved in P c ycling and availability will be useful in the development of effective stra tegies to reduce P losses from agricultural soils, which will include match ing crop needs with soil P release and the development of appropriate remed iation techniques to reduce P availability in high P status soils.