A laboratory evaluation of ammonia volatilization and nitrate leaching following nitrogen fertilizer application on a coarse-textured soil

In a series of field studies, differing rainfall patterns within the first month after N fertilizer application to a coarse-textured soil significantly affected yields and N-use effciency of irrigated corn (Zea mays L.), and responses varied with N source. A laboratory study was conducted to evaluate effects of N source with precipitation following N application to a coarse-textured soil. Nitrogen sources included urea-ammonium nitrate solution (UAN), UAN with additives of either nitrapyrin (2-chloro-6- [trichloromethyl] pyridine) as a nitrification inhibitor or maleic-itaconic acid copolymer as a urease and nitrification inhibitor, or polymer-coated dry urea (PCU).fiese products were applied to soil in chambers from which ammonia (NH₃) volatilization and nitrate (NO₃^-) leaching were measured over 31 d following fertilization. Precipitation events simulated rainfall frequencies and amounts that occurred in field studies in dry and wet conditions. Ammonia volatilization was lower in wet than dry conditions. Total NH₃ loss for the dry precipitation regime ranged from 11 to 18% of applied N fertilizer for all treatments except PCU (<1%). In contrast, all treatments in wet conditions had low NH₃ loss (<1% of applied N). However, substantial NO₃^- leaching occurred with wet conditions, comprising 48 to 66% of applied N for most treatments. Leaching loss was the greatest for UAN, followed by UAN with additives. For either dry or wet environments, losses of N from PCU to either NH3 volatilization or NO₃^- leaching were negligible.