Efficacy of enhanced efficiency nitrogen fertilizer on ammonia volatilization in varied soil moisture conditions

Abstract Enhanced efficiency nitrogen fertilizers (EENFs) are modified forms of nitrogen fertilizer used to reduce nitrogen loss such as ammonia and nitrous oxide. While these EENFs aim to combat nitrogen loss, environmental impacts, such as moisture, may still influence nitrogen loss through ammonia volatilization. This study aims to further understand the influence of varied soil moisture conditions on the efficacy of urea‐based EENFs. An incubation system with a random block design of four replicates was utilized to evaluate both urea and urea ammonium nitrate (UAN) EENFs applied at three moisture content levels. These levels were assigned and treated at 2/3×, 1×, and 2× field capacity. Urea + EENF resulted in greater ammonia loss than UAN + EENF at 1× and 2× field capacity, indicating a possible difference in efficacy between the two EENFs. Additionally, both EENF forms of urea and UAN had the greatest percent loss of applied N at 2× field capacity, revealing the inefficient use of EENFs on soils with high moisture content.