The Importance of Sunbsurface Flow in Soil Phosphorus Loss.

Soil phosphorus (P) loss has been historically believed through pathways of surface runoff and erosion. However, recent studies have increasingly evidenced that sub-surface runoff or title drainage can account for 22 to 98% of the total soil P loss. Partition of soil P loss between tile drainage and surface runoff is a function of tile spacing, but the optimum tile spacing can vary with soil types. Particular P often plays an important role in soil P loss in tile drainage water, followed by the dissolved reactive P. Variation of P loss in tile drainage water, including seasonality, magnitude, and relative importance to total soil P loss, is significant. Factors affecting P form distribution and their concentrations and magnitudes of loss in tile water can include those (soil, weather, crop, management practices) that are eventually related to soil P status (i.e. degree of P saturation, solubility), dispersibility, and hydrological properties (i.e. porosity and size distribution, amount of discharge and flow rate). This review paper will discus the up-to-date research findings by using case studies that have been conducted in large field plots equipped with most advanced auto-sampling and monitoring systems.