CAN WATER TREATMENT RESIDUALS BE INTEGRATED INTO BEST MANAGEMENT PRACTICES TO REDUCE NONPOINT SOURCE POLLUTION OF THE CHESAPEAKE BAY BY AGRICULTURAL PHOSPHORUS?

Phosphorus (P) enrichment in the Chesapeake Bay, Delaware's Inland Bays and their tributaries by surface and subsurface runoff from agricultural fields has been implicated in the degradation of water quality in these important surface waters. In 1998, the State of Maryland passed legislation requiring the development and implementation of N and P-based management plans for agricultural systems using fertilizers by 2001 and for those using organic wastes (manures, biosolids) by 2005. The State of Virginia passed similar legislation in 1999, focusing on N and P-based management plans for the poultry industry. In June of 1999, the State of Delaware passed a Nutrient Management Act which restricts the amount of P that can be applied to “high P” soils. In addition to the state nutrient management laws and associated regulations, Total Maximum Daily Load (TMDL) agreements have been negotiated between state environmental agencies in Delaware (1997) and Virginia (1998) and USEPA that have identified P as a key factor in the nonpoint source pollution of many streams, rivers, ponds, and bays and called for the development of pollution control strategies to reduce P losses to surface waters. Maryland does not have a TMDL agreement but a lawsuit has been filed to compel USEPA to establish TMDLs for impaired water bodies in that state.Many soils in this watershed are now considered “excessive” in soil test P from an agronomic standpoint. This has raised serious questions about the potential for soluble and particulate P from agricultural fields to contribute to nonpoint source pollution of the Chesapeake Bay and its tributaries. A major contributing factor to the widespread distribution of high P soils in this watershed has been the long-term use of animal wastes, alone or in conjunction with commercial fertilizer P. This has resulted in an accumulation of P in soils with time, which increases the likelihood of P losses in runoff and eventually to the leaching and subsurface runoff of P in some soils. The traditional approach to reduce P losses from soils to water has been to install buffer strips, grassed waterways, use fall cover crops, and the like. While these practices are effective at trapping sediments (particulate P) they have little influence on the loss of soluble P. Recent research in the U.S. and some European countries has evaluated the effectiveness of water treatment residuals (WTRs) as soil amendments for buffer zones that are installed to reduce the transport of soluble P from agricultural soils to surface waters. This presentation discusses an approach to evaluate, demonstrate, and integrate into existing water quality programs the use of WTRs as components of best management practices (BMPs) for P control in the Chesapeake Bay Watershed.