Reduction in soil N₂O emissions by pH manipulation and enhanced nosZ gene transcription under different water regimes

Several studies have been carried out to examine nitrous oxide (N₂O) emissions from agricultural soils in the past. However, the emissions of N₂O particularly during amelioration of acidic soils have been rarely studied. We carried out the present study using a rice-rapeseed rotation soil (pH 5.44) that was amended with dolomite (0, 1 and 2 g kg^-1 soil) under 60% water filled pore space (WFPS) and flooding. N₂O emissions and several soil properties (pH, NH₄⁺N, NO₃^--N, and nosZ gene transcripts) were measured throughout the study. The increase in soil pH with dolomite application triggered soil N transformation and transcripts of nosZ gene controlling N₂O emissions under both water regimes (60% WFPS and flooding). The 60% WFPS produced higher soil N₂O emissions than that of flooding, and dolomite largely reduced N₂O emissions at higher pH under both water regimes through enhanced transcription of nosZ gene. The results suggest that ameliorating soil acidity with dolomite can substantially mitigate N₂O emissions through promoting nosZ gene transcription.