Surface Runoff and Shallow Ground Water Quality as Affected by Center Pivot Applied Dairy Cattle Wastes

Abstract

ABSTRACT DAIRY cattle wastes were applied to separate areas by center pivot irrigation at mean N rates of 91 and 44 kg/ha per month. Total N was determined on surface runoff samples from each area. Nitrate contamination of shallow ground water was measured in water samples collected from 23 sites, with each site having piezometers at 1.2, 2.4, and 3.6 m. Total cumulative N loads in surface runoff for June 1982-February 1985 from the high and low wastewater rates were 147 and 47 kg/ha, respectively. Mean monthly NO3 N concentrations of 10-70 mg/L, 10-50 mg/L, and 5-35 mg/L were found in the shallow, intermediate, and deep piezometers, respectively. Significant differences in shallow ground water N03~N concentrations were not found between the two wastewater application rates. Substantial NO3 N contamination at 3.6 m occurred despite dense very slowly permeable plinthic and subsoil materials.