Comparison of Ammonia Volatilization from Surface Applied v. Incorporated Fertilizers on High, Neutral, and Low pH Soils.

The volatilization of ammonia (NH₃) from urea and ammonium based fertilizer causes negative environmental and economic impacts especially when fertilizer are not incorporated following application. Urea, the most common nitrogen (N) source, and other ammonium based fertilizers can be susceptible to rapid NH₃⁺ volatilization immediately following fertilizer application. In the past decade, many enhance efficiency N fertilizer have been developed using technologies to inhibit urease enzyme production and nitrification and thereby increase N use efficiency and decrease the environmental impact of NH₃ volatilization. The objective of this study was to compare NH₃⁺ volatilization from non-incoporated and incorporated Urea, ammonium-based, and enhance efficiency N fertilizers. Ammonia volatilization was measured over a 10 and 28 d period on soil pH of 8.0; showing volatilization peaked the second or third day for urea and peak times varying for products containing urease inhibitors after application of fertilizer. Comparison of NH₃ volatilization from the different N-based fertilizers showed urea had the highest N loss from NH­₃ volatilization (14.4%, Fig. 1). The NBPT enhanced efficiency fertilizers (Agrotain, Limus, and Eclipse) and the urea/AMS had less N loss from NH₃ volatilization (2.0 – 3.2%) than urea, but more than Fūsn and AMS (1.1 and 1.6%, respectively). A comparison of incorporate (IN) versus non-incorporated (NIN) showed urea had the highest amount of N loss from ammonia volatilization over the 10 d study (16.4 % N loss INC) and (18.1 % N loss NIN) The non-urea fertilizer had low amounts of NH₃⁺ volatilization (AMS 2.5 % N loss INC) and (2.1 % N loss NIN) FUSN (1.8 % N loss INC) and (1.7 % N loss NIN) Agrotain (1.2 % N loss INC) and (1.2 % N NIN Fig. 2). These data suggest that enhanced efficiency mechanisms (NBPT or polymer coat) were successfully in reducing N loss from NH₃ volatilization, but incorporation of the fertilizer did not reduce NH₃ volatilization.