NITRATE MONITORING AND GLEAMS SIMULATION FOR POULTRY LITTER APPLICATION TO PINE-SEEDLINGS

Nitrate leaching below the root zone was monitored and a water quality model was simulated for poultry litter application to pine seedlings. The six treatments used in this experiment were 4.5, 9.0, and 18.0 t/ ha of poultry litter, 4.5 t/ha of poultry litter with intensive weed c ontrol, commercial fertilizer, and a control. Nitrate-N concentrations were determined from the top 80 cm of the soil profile and from water sampled 61 cm below the surface. The water quality model GLEAMS was a pplied to predict NO3-N concentrations in the subsurface water and in the soil profile. For all treatments, NO3-N concentrations in soil lea chate far exceeded 10 mg/L during the first seven months following ame ndment application, but they dropped below 10 mg/L for the rest of the 15-month study period. Measured leachate concentrations were greatest for the commercial fertilizer treatment. Soil NO3-N concentrations we re highest in the top 10 cm of the soil profile, but they were not sig nificantly different from pre-treatment concentrations nine months aft er amendment application, nor were there any significant differences a mong treatments. The model accurately predicted NO3-N leachate concent rations for the poultry litter treatments, although it underestimated concentrations for the control and commerical fertilizer treatment. Si mulated soil NO3-N concentrations were higher than average measured va lues in most cases.