Joint mitigation of NH3 and N2O emissions by using two synthetic inhibitors in an irrigated cropping soil

Abstract

Ammonia (NH3) emissions from cropping systems are a major pathway of nitrogen (N) loss thus strongly affecting nitrogen use efficiency (NUE). The agriculture sector is responsible for ca. 94% of global NH3 emissions, mostly associated with manure management (56%), animal manure applied to soil (18%) and inorganic N fertilization (21%). Furthermore, N fertilization enhances N2O emissions from cropping systems. The assessment of NH3, and also N2O, abatement strategies on a regional basis has, therefore, become a strategic priority for sustainable food production worldwide.A field experiment, under Mediterranean conditions, was carried out to assess the N2O and NH3 mitigation efficiency of different synthetic inhibitors in an irrigated maize crop fertilized with urea (U). The nitrification inhibitor (NI) 3,4 dimethylpyrazole succinic acid (DMPSA), and the combination of the DMPSA and the urease inhibitor (UI), N-(n-butyl) thiophosphoric triamide (NBPT), were used in the experiment. Our findings indicate that, following top-dressing N fertilization, the highest NH3 emissions were observed after U + NI and U applications (12.2 and 11.1 kg N ha−1, respectively), with no significant differences between them. The application of urea with both inhibitors (U + 2I) significantly reduced these emissions down to 3.3 kg N ha−1. During canopy senescence, NH3 emissions were not negligible and were statistically similar between treatments, with an average value of 2.3 kg N ha−1. In addition, the treatments with NI were effective in reducing cumulative N2O losses (ca. 79%).