The effect of controlled soil temperature on diel CH4 emission variation

During the 1994 dry season, diel methane emission variations were monitored in the greenhouse and the phytotron of the International Rice Research Institute, Los Baños, Philippines at ambient and artificial soil temperature regimes using a closed chamber technique. Diel soil temperature regimes affected methane emission rates. Under ambient temperature regime, methane fluxes increased with rising soil temperature in the morning and reached a maximum in the early afternoon, then decreased rapidly and leveled off at night while soil temperature declined gradually till sunrise next morning. Changing diet soil temperature regimes resulted in changes in diel methane emission patterns irrespective of the amplitudes of the methane emission rates. Using Arrhenius equation to simulate temperature dependence of methane emission variations indicated that soil temperature is a major factor controlling diel methane emission variations (r2 = 0.78).