Ammonia volatilization from fertilizer sources on a loam soil in Idaho

Abstract

Optimizing crop N uptake while minimizing NH3 volatilization from N fertilizer sources is a critical part of agricultural best management practices. Urea is the most widely used N fertilizer but is also one of the most susceptible to losses as NH3. Fertilizer sources and additives can be used to reduce NH3 volatilization. Specifically, urease inhibitors [e.g., N-(n-butyl) thiophosphoric triamide (NBPT)] can reduce NH3 volatilization from urea. A novel fused ammonium sulfate nitrate (ASN) product has recently been developed as another potential alternative N fertilizer source but has not been studied widely. A field study was performed to quantify NH3 volatilization from the newly available ASN fertilizer as compared with various N fertilizers (ammonium sulfate [AS] and urea) including urea treated with the urease inhibitor NBPT in an alkaline calcareous loam soil in Idaho. Further, we assessed NH3 volatilization from surface applied and incorporated N fertilizers from these various N sources. Untreated surface-applied urea volatilized the highest amount of NH3, whereas incorporation of N fertilizers was effective in reducing volatilization as compared with untreated surface-applied urea. Our study indicated that the N fertilizer sources (AS, ASN, and urea+NBPT) were equally effective in reducing NH3 volatilization when compared with surface-applied urea. Our study will help refine N fertilizer management under multiple field situations and traditional management practices of crop producers in the western United States. Further, site-years and study locations would be needed to provide evidence of the effectiveness of ASN in reducing NH3 volatilization under a wider range of soil and environmental conditions.