Impact of a Nitrification Inhibitor on Nitrogen Losses in Contrasting Soils and Water Regimes

Abstract

Nitrification inhibitors, such as 3,4-dimethylpyrazole phosphate (DMPP), can reduce nitrogen (N) losses, but their efficiency depends on the edaphoclimatic conditions. The aim of our study was to compare N losses, nitrate leaching and ammonia volatilization, from soils with contrasting texture and precipitation regimes fertilized with urea or urea treated with DMPP under controlled conditions. Methods: Columns of two different soils (Soil A: sandy-loam, Soil B: clay-loam) were subjected to three N-source treatments [no fertilization (CONTROL), urea, and urea with DMPP) and two water regimes equivalent to a wet or dry season (WET and DRY, respectively). Nitrogen losses by ammonia volatilization and nitrate leaching were measured over 42 d. Results: For both soils, DMPP decreased nitrate leaching in the WET regime (-27% and − 67% in Soil A and B, respectively), outweighing any observed ammonia volatilization increase (+ 15% and + 39% in Soil A and B, respectively). Conversely, under DRY conditions, DMPP’s effect on nitrate leaching was minimal in Soil B and, in Soil A, the increased ammonia emissions (+ 39%) negated the benefits of reduced nitrate leaching. Conclusion: These results highlight the critical role of edaphoclimatic factors in determining the effectiveness of DMPP, emphasizing the need for site-specific application strategies.