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 efficiency 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). These products were applied to soil in chambers from which ammonia (NH 3 ) volatilization and nitrate (NO 3 − ) 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 NH 3 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 NH 3 loss (<1% of applied N). However, substantial NO 3 − 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 NH 3 volatilization or NO 3 − leaching were negligible.