Agronomic and Environmental Implications of Phosphorus Management Practices

Phosphorus (P) is an essential nutrient for growth of plants and aquatic organisms. Fertilizer or manure P application to land often is necessary to achieve or maintain optimal levels of crop production. However, P applications seldom are needed in high-testing soils and excessive applications can result in increased P delivery to water resources. Excessive nutrient levels can result in eutrophication of surface freshwater resources. The movement of P from agricultural land to water bodies is a complex process involving several source factors, transport factors, and multiple delivery pathways. Phosphorus moves into surface water attached to particulate matter eroded from the land and as dissolved P in surface runoff or subsurface tile drainage. It can also move into groundwater mainly as dissolved P.