Submitted to: World Congress of Soil Science
Publication Type: Proceedings
Publication Acceptance Date: August 20, 2002
Publication Date: August 20, 2002
Citation: WASSMANN, R., BUENO, C.S., LANTIN, R.S., LU, W.F., CHAREONSILP, N., OLK, D.C. STRAW MANAGEMENT AFFECTING METHANE EMISSIONS FROM DIFFERENT RICE ECOSYSTEMS. WORLD CONGRESS OF SOIL SCIENCE. 2002. CD-ROM. BANGKOK, THAILAND.
Emissions of the greenhouse gas methane from wetland rice fields are generally enhanced by organic inputs into the soil. This study investigates methane emissions and crop residue management at three sites: Los Banos (Philippines), Hangzhou (China), and Prachinburi (Thailand). In Los Banos, the common practice of incorporating rice straw late during field preparation resulted in seasonal mean emissions of 30 to 250 mg methane m-2 d-1. Early residue incorporation (i.e. approximately 30 d before field preparation) reduced emissions by 81%, 18% and 54% in the wet season 1996, dry season 1997, and wet season 1997, respectively. Grain yields did not differ significantly between treatments. In Hangzhou, late incorporation of rice straw resulted in high emissions (>250 mg methane m-2 d-1). Emissions could be reduced by about 10% when the straw was incorporated before the winter fallow (early season) and was mulched (late season). Experiments in Prachinburi were conducted in deepwater rice, yielding high straw biomass due to the elongation of rice plants. The common practice of straw burning (followed by soil incorporation of ash) resulted in low emissions (<90 mg methane m-2 d-1) during the vegetative period, but this practice implied methane emission and air pollution during the burning process. Methane emissions were generally high (>300 mg methane m-2 d-1) when fresh straw was incorporated into the soil. Emissions were low when the straw was either composted or mulched on the soil under zero tillage. Results from all three locations indicate that methane emissions from rice fields not only depend on quantity of rice straw but also on mode and timing of incorporation.