Study on Diurnal Variations of CH₄ Fluxes from Rice Soils in Pots

A pot culture experiment of rice in greenhouse was carried out to investigate the diurnal variations of CH₄ fluxes,soil temperatures and soil Eh during rice growing period with different treatments applied in the former winter cropping season.The results showed that there existed obvious diurnal variations of CH 4 fluxes and soil temperatures in continuous fine days.The maximum fluxes occurred at 4 pm while the minimum fluxes at about 4 am,and the variation patterns of CH₄ fluxes and soil temperatures were in conformity with cosine function of time t as a variable.Methane fluxes in continuous overcast and rainy days had a decreasing tendency day by day,and its diurnal variations could not be fitted with a cosine functional curve of time t .Diurnal variations of CH₄ fluxes were mainly influenced by soil temperature at 0 10 cm soil depth.And there is no influence of soil Eh on diurnal variations of CH₄ fluxes.