Further understanding of nitrous oxide emission from paddy fields under rice/wheat rotation in south China

This paper reported the quantitative contribution of three important dry-wet cycles to N2O emission in annual rotation, and compared N2O emission patterns during rice and wheat seasons affected by diverse causes-induced dry-wet cycles based on in situ measurements for 2 consecutive years (from 2007 to 2009). Results showed that 50-70% of the annual N2O emission was emitted during wheat season and 30-50% during rice season. During rice seasons, greatest flux occurred immediately after preflooding at the start of rice season, accompanied by peaks of NO3 concentrations in soil water. N2O emission during the preflooding period contributed 80-84% of seasonal emission, far higher than 7.6-8.4% released during midseason aeration and 5.0-7.4% during drainage period. Variation of N2O emission in wheat season was much greater than that in rice season. In the Taihu lake region, controlled water management determined emissions of N2O in rice season, whereas variation of natural precipitation and temperature determined N2O emission pattern during wheat season.