The Influence Of Different Treatment On Methane And Nitrous Oxide Emissions Of Chaohu Polder

In this paper,effects ofCH₄ and N₂O emissions in different farming and different water control methods under rice-wheat rotation in Chaohu during wheat season on farmland soil were studied to explore the economic technology suitable for polders in Chaohu with better yield and lower emissions.Polders of rice-wheat rotation farmland in Chaohu had been under experimental observation from 2013 to 2015.In this study,surveillance sites were set up in Tongyang Town of Chaohu in Anhui and six treatments were in process including conventional treatment?CG?,fertility development?CY?,no-tillage fertility development?CB?,straw incorporation with fertility development?CJ?,conventional treatment with drainage via shallow ditch in wheat season?CQ?,conventional treatment drainage via deep ditch?CS?.Each treatment set 3 repetitions.Results were as follows:1.In a complete cycle of rice-wheat rotation,comprehensive greenhouse effects under different farming methods were mainly due to emissions of CH₄.Besides,CH4emissions of paddy fields occupied the majority in paddy season and wheat season,which led to the focus of the study on greenhouse gases reduction of polders in Chaohu during rice-wheat rotation.2.Compared with CG,in different water control methods,N2O emissions of CQ and CS rose or fell with an uncertain trend,and even in some years emissions increased.But from the perspective of the whole cycle of rice-wheat rotation under CQ and CS treatment,the reduction of emissions in CH4 offset the increase of missions in NO₂,by which the total emissions of greenhouse gases in paddy season and wheat season gained a lower value than those of other 4 treatments.Thus,both treatments of CQ and CS with different water control methods obtained a significant effect to reduce emissions.3.Under treatments of CG,CY,CB and CJ,emissions of CH₄ in paddy fields 4during paddy season presented a triple peak pattern commonly.Emission peaks occurred respectively in the early period of the rice tiller,the early booting and flowering stage,early filling and mature stage.However,emissions of CH₄in winter wheat fields under treatments of CQ and CS presented the trend of a single peak pattern in paddy season.Under treatments of CQ and CS,emissions of CH4 retained in a low level in later growing period of paddy,which led to a total emissions much lower than those of other treatments.4.In paddy season,the nitrogen content of soil played a critical role in emissions of CH₄ in paddy fields.Compared with those under CG treatment,emissions of N₂Ounder treatments of CB and CJ showed the effect of stable reduction,but for CY reduction owned its volatility.Compared with those of CG,emissions of N₂O under CY treatment were 28.57%higher in 2013;28.57%lower in 2014 and 29.09%lower in2015.In wheat season,compared with those of CG,N₂O emissions under CY and CJ gained more stable reduction.However,for CB,reduction was less stable.In terms of the whole growing period of paddy and wheat,CJ treatment brought stable reduction inN₂O emissions in both paddy season and wheat season,while reduction of CY and CB gained different levels of volatility.5.Emissions of CH₄ in paddy fields under rice-wheat rotation system,in paddy season and wheat season,accounted for the majority in the whole cycle from the perspective of the percentage which CH₄emissions owned in the whole CO₂equivalence(CO_2-e).In addition,the proportions which CH₄ and N₂O occupied in CO_2-e during the whole cycle of rice-wheat rotation indicated that emissions of CH₄ in wheat fields and paddy fields was the main contributor to greenhouse effect.Therefore,reduction of greenhouse gases in polders from Chaohu should pay special attention to CH₄ emissions from paddy fields6.Compared with the treatment of CG,CQ and CS showed better economical yield to different extent both in paddy season and in wheat season:in the paddy season,the yield increased by 1.54%and 0.35%respectively,and in the wheat season it increased by 3.28%and 2.88%respectively.Above all,treatments of CQ and CS showed excellent effects on both the reduction of greenhouse gases in farmland and the improvement of economic yield,which was suggested the suitable and efficient measure to reduce emissions under rice-wheat rotation system for polders from Chaohu.