Runoff Water Quality from Poultry Litter‐Treated Pasture and Forest Sites.

In the Ozark Highlands of the USA (36–38° N, 91–95° W), annual application of poultry litter to pasture land is a routine waste management practice. The objective of this study was to measure the effect of site characteristics and poultry litter application on runoff and nutrient transport from grazed pasture and forest sites at different landscape positions. Sixteen pairs of 1 × 2 m plots were established on Nixa (loamy‐skeletal, siliceous, active, mesic Glossic Fragiudults) and Clarksville (loamy‐skeletal, siliceous, semiactive, mesic Typic Paleudults) cherty silt loams. One plot of each pair received 4.5 Mg ha−1 of poultry litter. Rainfall was simulated at 75 mm h−1 for 1 h (25‐yr return period storm) one month after litter application. A composite runoff sample was analyzed for dissolved reactive phosphorus (DRP), total phosphorus (TP), ammonia N (NH3‐N), nitrate N (NO3‐N), total Kjeldahl nitrogen (TKN), and total suspended solids (TSS). Poultry litter‐treated plots had consistently higher concentrations of all water quality parameters tested compared to untreated plots. Concentration of DRP in runoff from untreated plots was linearly correlated with three soil P tests (0.35 < r2 < 0.85). Soil P on litter‐treated plots had little effect on runoff DRP, which averaged 2.20 mg L−1. High variation in runoff resulted in only NO3‐N showing significantly greater losses due to poultry litter treatment at two pasture sites. Results indicate that variation in runoff has a significant effect on nutrient transport from grazed pastures receiving poultry litter. [ABSTRACT FROM AUTHOR]