Reduction in soil N 2 O emissions by pH manipulation and enhanced nosZ gene transcription under different water regimes.

Several studies have been carried out to examine nitrous oxide (N2 O) emissions from agricultural soils in the past. However, the emissions of N2 O 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. N2 O 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 N2 O emissions under both water regimes (60% WFPS and flooding). The 60% WFPS produced higher soil N2 O emissions than that of flooding, and dolomite largely reduced N2 O 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 N2 O emissions through promoting nosZ gene transcription.