Volatilization and nitrification of nitrogen from urine under simulated cattle feedlot conditions

Abstract

Animals fed for slaughter are being concentrated in large feedlots, and, in some cases, contamination of ground and surface water supplies has resulted. In laboratory model studies, the amounts of ammonia volatilization and nitrate accumulation under simulated feedlot conditions depended on the moisture content of the soil. When urine was added every 2 days to an initially wet soil at the rate of 5ml per 21 cm/sup 2/, less than 25% of the added N was lost as ammonia and about 65% was converted to nitrate. When urine was added every 4 days to initially dry soil, essentially all the water evaporated between urine additions, and 90% of the added N was lost as ammonia. These findings suggest that the stocking rate and other management factors should be considered in pollution abatement.