Effects of Alkaline-Clay Mineral Complex On Methane Gas Emission in Paddy.

Rice cultivation in paddy field affect the global balance of the key greenhouse gases, such as CO2 and CH4. They act as sink for CO2 by photosynthetic assimilation from atmosphere and sequestrayion of the organic matter produced in the paddy soil, while paddy soil might be sources of CH4. The aim of the study were to estimate the effect of alkaline material on methane gas emissions from paddy soil. Gas samples were collected using a closed chamber technique and analyzed by gas chromatography equipped with flame ionization detector. Compared to control, methane emission were significantly lower (P≤0.01) in alkaline-clay mineral complex treatment. Results of chemical speciation model (MINTEAQ) showed that precipitation such as CaCO3, MgCO3 etc., would reduce methane in pore water. Although methane emission in paddy soil was influenced by chemical status including redox potential and organic matter decomposition etc, these results are imply that precipitation reaction by inorganic carbon such as carbonate, bicarbonate also affects controlling a methane gas emission.