Effect of Irrigation Rate on Ammonia Volatilization

Sprinkler irrigation can limit N loss from NH3 volatilization when urea is surface applied. This study was conducted to find the effective irrigation rate needed to limit NH3 loss from volatilization when urea is surface applied. A gradient of six irrigation rates (0.0, 1.3, 3.8, 7.6, 11.4, and 21.6 mm) was used to find the effective irrigation rate for urea incorporation. Ammonia was collected by the modified passive flux method for 23 d after urea application. Cumulative NH3 loss ranged from 3.1 to 67.3 kg N ha−1, with 7.6 mm of irrigation water reducing losses to 19.4 kg N ha−1. The result of this gradient irrigation study predicts that NH3 losses can be reduced by 90% by applying 14.6 mm of irrigation water immediately after urea application. Decreased NH3 loss associated with higher irrigation rates led to increased wheat (Triticum aestivum L.) N concentrations. The application of 14.6 mm of irrigation water successfully incorporated urea and reduced losses from NH3 volatilization.