Aqueous and gaseous nitrogen losses induced by fertilizer application

In recent years, concern has grown over the contribution of nitrogen (N) fertilizer use to nitrate (NO 3 − ) water pollution and nitrous oxide (N 2 O), nitric oxide (NO), and ammonia (NH 3 ) atmospheric pollution. Characterizing soil N effluxes is essential in developing a strategy to mitigate N leaching and emissions to the atmosphere. In this paper, a previously described and tested mechanistic N cycle model (TOUGHREACT‐N) was successfully tested against additional observations of soil pH and N 2 O emissions after fertilization and irrigation and before plant emergence. We used TOUGHREACT‐N to explain the significantly different N gas emissions and nitrate leaching rates resulting from the different N fertilizer types, application methods, and soil properties. The N 2 O emissions from NH 4 + ‐N fertilizer were higher than from urea and NO 3 − ‐N fertilizers in coarse‐textured soils. This difference increased with decreases in fertilization application rate and increases in soil buffering capacity. In contrast to methods used to estimate global terrestrial gas emissions, we found strongly nonlinear N 2 O emissions as a function of fertilizer application rate and soil calcite content. Speciation of predicted gas N flux into N 2 O and N 2 depended on pH, fertilizer form, and soil properties. Our results highlighted the need to derive emission and leaching factors that account for fertilizer type, application method, and soil properties.