TY - JOUR T1 - Nitrogen and phosphorus runoff from cropland and pasture fields fertilized with poultry litter JF - Journal of Soil and Water Conservation SP - 400 LP - 412 DO - 10.2489/jswc.64.6.400 VL - 64 IS - 6 AU - R.D. Harmel AU - D.R. Smith AU - R.L. Haney AU - M. Dozier Y1 - 2009/11/01 UR - http://www.jswconline.org/content/64/6/400.abstract N2 - Application of litter and other organic by-products to agricultural land off site of animal production facilities has created both environmental concerns and agro-economic opportunities, but limited long-term, field-scale data are available to guide management decisions. Thus, the objective of this study was to determine the water quality effects of repeated annual poultry litter application as a cropland and pasture fertilizer. Eight years of data collected on ten field-scale watersheds indicated several significant water quality differences based on litter rate (0.0 to 13.4 Mg ha−1 [0 to 6 ton ac−1]) and land use (cropland and pasture). On cropland fields, increasing litter rates (with corresponding decreases in supplemental inorganic nitrogen [N]) increased runoff orthophosphate phosphorus (PO4-P) concentrations but reduced extreme high nitrate nitrogen (NO3-N) concentrations. Whereas runoff PO4-P concentrations were somewhat similar between land uses, NO3-N concentrations were much lower in pasture runoff because of supplemental inorganic N application, reduced nutrient uptake potential, and faster litter mineralization on cropland. Although considerable variability was observed, intra-annual runoff NO3-N and PO4-P concentrations generally exhibited curvilinear decay based on time since fertilizer application. In spite of repeated annual litter application and buildup of soil phosphorus (P) at high litter rates, few long-term trends in N and P runoff were evident due to the dynamic interaction between transport and source factors. These results support several practical implications, specifically: (1) combining organic and inorganic nutrient sources can be environmentally friendly and economically sound if application rates are carefully managed; (2) high runoff N and P concentrations can occur from well-managed fields, which presents difficulty in regulating edge-of-field water quality; and (3) change in the animal industry mindset to view by-products as marketable resources could mitigate environmental problems, provide alternative fertilizer sources, and enhance animal industry revenue opportunities. © 2009 by the Soil and Water Conservation Society ER -