Abstract:
The objective was to reveal nitrous oxide (N
2O) fluxes from double-cropping rice field affected by soil enzyme activities under different irrigation modes and nitrogen (N) treatments. The effects of three irrigation modes (conventional irrigation CR, “shallow-wet-dry” irrigation TR and alternate wetting and drying irrigation DR) and three N treatments (FN1: 120 kg hm
−2: 20% basal fertilizer, 40% tillering fertilizer and 40% panicle fertilizer), FN2: 120 kg hm
−2: 50% basal fertilizer, 25% tillering fertilizer and 25% panicle fertilizer) and FN3: 90 kg hm
−2: 50% basal fertilizer, 25% tillering fertilizer and 25% panicle fertilizer) on N
2O fluxes and enzyme activities were investigated using field experiments of double-cropping rice, and the relationships between N
2O fluxes and enzyme activities were analyzed. N
2O fluxes in TR and DR modes were 92.82% and 175.95% higher than that in CR mode, and N
2O flux in FN3 was 39.7% lower than that in FN2. Compared with CR mode, TR mode increased soil urease activities, and DR mode increased soil hydroxylamine and nitrite reductase activities. There were significantly positive correlations between N
2O flux in the double-cropping rice field and the activities of urease (late rice field: correlation coefficient of 0.38; early rice field: correlation coefficient of 0.63), nitrate reductase (late rice field: correlation coefficient of 0.33; early rice field: correlation coefficient of 0.61) and hydroxylamine reductase (late rice field: correlation coefficient of 0.63; early rice field: correlation coefficient of 0.73) in soil. The activities of urease, nitrate reductase and hydroxylamine reductase in soil significantly affected N
2O fluxes in double-cropping rice field under different irrigation modes and N treatments.