Water quality impacts of conservation and nutrient management practices in Pennsylvania

Abstract

ABSTRACT: A field-scale microcomputer model, CREAMS, was used to assess the impacts of selected best management practices (BMPs) and nutrient management programs (NMPs) on sediment and nutrient losses from three locations with three soil and field configurations common to the Chesapeake Bay drainage area in Pennsylvania. Several BMPs were evaluated, with CREAMS simulations conducted for runoff, erosion, sediment and nutrient delivery to the field boundary, and percolation and nitrate leaching through the crop root zone. Two separate NMPs were evaluated in combination with the BMPs. The baseline NMP followed traditional manure and fertilizer application practices and the improved NMP used an improved, high management system that incorporated best timing, placement, and types of nutrient additions. BMPs increased percolation and decreased runoff compared to moldboard plowing with no conservation practices. Sediment exported from the fields was also reduced by the use of BMPs. Reductions in total nitrogen (N) and phosphorus (P) losses varied greatly for different BMPs and sites. Although BMPs reduced sediment-associated N and P losses, the improved NMPs, as compared with the traditional baseline NMP, had little effect on these losses. BMPs tended to increase, whereas the improved NMPs substantially reduced, nitrate leaching. The improved NMPs also greatly reduced P losses from those sites where P loss was predominantly in soluble form rather than sediment associated. The use of BMPs and improved NMPs together effectively reduced sediment and total nutrient losses.