Ammonia Volatilization from Nitrogen Fertilizers Surface Applied to No‐till Corn

Abstract

AbstractLow use efficiency has frequently been observed when N fertilizers, particularly those containing urea, are applied directly on the surface residue in no‐till corn (Zea mays L.) production systems. A portion of this low use efficiency has been attributed to volatilization of NH3. Field experiments were conducted at two locations in Indiana to make direct measurements of NH3 volatilization from granular urea, cogranulated urea‐urea phosphate (UUP), urea‐ammonium nitrate solutions (UAN) and prilled ammonium nitrate (AN). The fertilizers were applied directly on corn residue at a rate of 168 kg N ha−1. On a Lyles sandy loam soil (Typic Haplaquolls) 50.9 kg of the 168 kg N ha−1 applied as granular urea was lost in 120 h, with essentially all that loss occurring in the first 50 h after application. Peak loss rates of 3.0 kg N ha−1h−1 occurred 23 h after application. No significant volatilization loss occurred with AN, while 26.0 kg N were lost through volatilization with UUP and 14.6 kg N lost from UAN. Peak loss rates at 23 h after application were 1.83 and 0.37 kg N ha−1h−1 for UUP and UAN, respectively. A 25‐mm rain shower effectively stopped volatilization approximately 50 h after application. On a Bedford silt loam soil (Typic Fragiudalfs) volatilization losses were considerably lower than those found on the lower cation exchange capacity Lyles soil. Though overall losses were lower, relative losses from the different N fertilizers were similar to those found on the Lyles soil.