Phosphorus In Drainage Waters Of The Atlantic Coastal Plain.

The Atlantic Coastal Plain region has had a long history of experimental and applied efforts to exclude phosphorus (P) from drainage waters. Early research focusing upon the chemical controls of soil and sediment P has given way to field studies aimed at refining our understanding of hydrologic pathways and sources of P in drainage effluent.  To some extent monitoring has helped to prioritize remedial strategies, with farmstead sources serving as principal sources of concern followed by soils of highest P status. Even then, soils of the Atlantic Coastal Plain are far from homogeneous. While drainage systems are generally designed to address regional water tables, textural discontinuities in coastal plain soils often serve to perch water, routing interflow along surface soil horizons and areas of highest P sorption saturation. Targeting surface soil P alone, however, can neglect substantial reserves in the subsoil. Recent trends in converting drainage ditches to subsurface tile drains present new concerns with regard to P leaching, especially following manure application. Integration of nutrient management, drainage management and agronomic management is necessary to overcome the many pathways that can exacerbate P transfers in this region.