Influence of controlled irrigation on CH₄ and N₂O emissions from paddy fields and subsequent greenhouse effect

The methane (CH₄) and nitrous oxide (N₂O) emissions from controlled irrigation paddy fields were observed by using the static chamber gas chromatography (GC) method.The objective of the study is to investigate the influence of the controlled irrigation technique on the CH₄ and N₂O emission process and the subsequent greenhouse effect.The results show that during a life cycle of rice crop,the total CH₄ emission from the controlled irrigation paddy field can be reduced by as much as 73.2% to 85.0% compared to that from the flood irrigation ones,and the emission is found to be most active in the early to mid-tillering stage of rice growth.By contrast,controlled irrigation would lead to a 10.6% increase in the total N₂O emission from paddy fields during the most tmie of rice growth.The average N₂O emissions from controlled and flood irrigation paddy fields are 106.65mg/m² and 96.40 mg/m²,respectively.It is estmiated that the global warming potential (GWPs) contributed by CH₄ and N₂O emissions from controlled irrigation paddy fields would be 726 kg/hm²,which should result in a 59.1% emission reduction compared with that from flood irrigation ones.Our study suggests that using the controlled irrigation technique would significantly reduce CH₄ and N₂O emissions and the subsequent GWPs.