Phosphorus dynamics in soils and landscapes

Abstract Transformations of P along both biological and pedologic pathways are reviewed and integrated in order to develop a comprehensive appreciation of P dynamics in soil ecosystems. The biological P cycle is driven by the essential role P plays in energy transport in biological systems. Mineralization of organic P is influenced by a process referred to as biochemical mineralization wherein hydrolysis of P is repressed by an ample supply of labile P and induced by a limited supply. Pedological P transformations are driven by leaching and increasing acidity which result in the weathering of primary minerals and the formation of secondary minerals. Although the biological cycle is more dynamic than the sluggish pedologic pathway, long-term evolution of P forms in soil ecosystems is controlled by the latter which continually moves P into a sink consisting primarily of occluded P. Occurrence of soluble P as an intermediate during P transformations accommodates translocation of P within soils and landscapes. Because both P content and forms and classes of Soil Taxonomy are related to stage of soil development, a relationship is proposed between taxonomic classes and P forms in soils.