APPLICATION OF GLEAMS TO PREDICT NUTRIENT LOSSES FROM LAND APPLICATION OF POULTRY LITTER

The GLEAMS (Groundwater Loading Effects of Agricultural Management Sys tem) (version 2.1) water quality model was used to predict nutrient (N and P) losses in surface and subsurface runoff, and their concentrati ons in soil layers, following application of two rates (9 and 18 t ha- 1) of poultry litter and a recommended rate of a commercial fertilizer on conventionally tilled corn plots at the Tennessee Valley Substatio n of the Alabama Agricultural Experiment Station. Model simulation res ults were compared with field data. The experiment included four repli cations for each of the three soil-amendment treatments. The GLEAMS si mulation of soluble and sediment P losses in surface runoff and NO3-N concentrations in leachate and soil layers were not consistent with fi eld data. Simulation of N-transformation effects on N losses in surfac e runoff did not agree with field data. The model simulated higher NH4 -N than NO3-N losses in surface runoff, while field data showed the op posite. The model simulated low concentrations of P in leachate at a 1 .0 m depth, while the observed data showed large variations.