保护性耕作模式下早稻田甲烷排放特征

Characteristics of CH4 emission in early rice paddy field under conservation tillage

  • 摘要: 目的研究耕作对早稻田甲烷排放的影响,并分析影响稻田甲烷排放的环境因子,寻找合适的耕作模式以减少稻田甲烷排放.方法设免耕不施肥、免耕施肥、常规不施肥和常规施肥4个处理,分别在水稻分蘖期和水稻抽穗期采用静态箱法收集气态甲烷(CH4),同步观测地温、采气箱内温度、环境温度、地表温度、草面温度、相对湿度及风速,探究早稻田CH4排放的日排放规律,明确免耕和施肥及环境因素对稻田CH4排放的影响.结果早稻田CH4的排放与气温、地表温度、5 cm土温、草面温度、相对湿度、风速等密切相关,尤其在分蘖期,各处理均与上述环境因子显著相关(P<0.05).不同耕作与施肥模式下,CH4日平均通量不同,在水稻分蘖期具体表现为常规施肥>常规不施肥>免耕施肥>免耕不施肥,在水稻抽穗期表现为常规不施肥>免耕施肥>常规施肥>免耕不施肥.结论免耕与常规耕作相比,早稻田CH4的排放量相对降低;施肥导致分蘖期早稻田CH4排放通量增加,但在抽穗期导致早稻田CH4排放减少.免耕可以减轻早稻田CH4的排放,其推广能为稻田减排做贡献.

     

    Abstract: ObjectiveThis paper aimed to research the effects of tillage methods on methane emission from early rice paddy fields,explore the environmental factors that affected methane emissions from paddy fields,and search for suit-able tillage pattern to reduce methane emissions from rice fields.MethodFour treatments were set:conventional tillage and no-fertilization ,conventional tillage and fertilizer ,no-tillage and no-fertilizer and no-tillage and fertilization. Gaseous methane(CH4)was gathered by using static box method at rice tillering stage and heading stage. At the same time, earth temperature,gas-collection box temperature,ambient temperature,surface temperature,grass surface tempera-ture,relative humidity and wind speed were observed. The study explored the diurnal variation of CH4 emission fluxes in early rice paddy fields and the effect of no-tillage,fertilization and environmental factors on CH4 emission from paddy field.ResultThe emission of CH4 in early rice paddy fields was closely related to air temperature,surface temperature, temperature of soil in 5 cm depth,grass surface temperature,relative humidity and wind speed. CH4 emission fluxes un-der four treatments were significantly related to the environmental factors(P<0.05) especially at tillering stage. The daily average CH4 emission fluxes under different treatments were different. At tillering stage,daily average CH4 emission fluxes were as follows: conventional tillage and fertilization>conventional tillage and no-fertilization>no-tillage and fertilization>no tillage and no-fertilization;the rank at heading stage was conventional tillage and no-fertilization>no-tillage and fertilization>conventional tillage and fertilization>no tillage and no-fertilization.ConclusionThe CH4 emission from paddy field in no-tillage treatment is lower than conventional tillage treatment. Fertilization results in an increase in CH4 emission from paddy fields at the tillering stage,but leads to a decrease in CH4 emissions from early rice paddy fields at heading stage. The extension of no-tillage contributes to the reduction of CH4 emissions from rice fields,which can be pro-moted in cultivation for emission reduction.

     

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