ABSTRACT
Phosphorus (P) is essential for plant growth and development. However, excess P application resulting from the imbalance between P input and output results in soil P accumulation. Phosphorus that accumulates on the soil surface serves as a potential P source during runoff events and is a major contributor to the eutrophication of aquatic systems. This chapter focuses on the management of P for agriculture and the environment. The first step in P management starts with soil testing and grouping soil into different fertility ratings for optimal crop yield. Soil test P (STP) is also used for environmental P loss assessment. Several studies have indicated a strong relationship between P loss in runoff and STP, where greater STP concentration resulted in higher P concentration in runoff. However, the relationship between STP and P loss is management specific and varies with soil type. A threshold P saturation ratio (PSR) is also used as an efficient tool to assess environmental P loss risk from P-impacted soils. Soil P storage capacity (SPSC) derived from the threshold PSR captures the risk of the previous loading and can quantify the safe storage capacity of P in the soil. Adoption of PSR/SPSC along with best management practices can be instrumental in P loss reduction from nonpoint sources.
