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

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.