Urease and nitrification inhibitors with drip fertigation strategies to mitigate global warming potential and improve water-nitrogen efficiency of maize under semi-arid regions

The limited availability of water resources and the significant loss of nitrogen oxides are severe constraints on agricultural development in dry-land agricultural systems of China. The field studies consisted of two new inhibitors (1) nitrification inhibitor (N) (3,4-dimethyl-1 H-pyrazol-1-yl) succinic acid isomer (DMPSA) and (2) urease inhibitor (U) N-butyl thiophosphorictriamide (NBPT) with three mulch drip fertigation irrigation treatments H (370 mm, conventional drip fertigation irrigation, referring to local actual agricultural irrigation standards), M (75% of H, moderate drip fertigation), L (50% of H, low drip fertigation), and CF: traditional flat planting without inhibitors and drip fertigation. The results indicate that drip fertigation irrigation with composite nitrification inhibitor can significantly reduce the N2O and CH4 cumulative emissions, thereby significantly reducing ET, GWP, and GHGI. Under the inhibitor-based strategy, the use of urease and nitrification reduced N2O loss by 42% and 60% compared with CF. In addition, RNH or RNM treatment can significantly enhance the content of SWS, NH4+-N, and NO3--N in the 0–120 cm depth, and significantly reduce the NO3--N leaching of the deeper soil. The N accumulation, grain N content, and N transport efficiency of corn significantly increase, which is helpful for improving grain yield. Under the action of two inhibitors, there was a significant difference between H and M drip fertigation irrigation. Compared with CF, the RNM with 75% reduced drip fertigation increase in average grain yield, biomass yield, CWPyield and CWPeco by 51%, 33%, 31%, and 57%, respectively. These results show that the use of H or M drip fertigation with nitrification inhibitor must be promoted in a rain-fed corn agro-ecosystem, in order to reduce GHG emissions without penalizing grain yield and leading to improves water-nitrogen efficiency of maize.