Effect of elevated temperature and rice straw application on methane emission from lowland rice paddy soils
2012
Gaihre, Y.K., [email protected]' [email protected] | Wassmann, R., International Rice Research Inst., DAPO Box 7777, Manila (Philippines) | Pangga, G.V., Philippines Univ. Los Baños, College, Laguna (Philippines) | Aquino, E., International Rice Research Inst., DAPO Box 7777, Manila (Philippines)
Irrigated lowland rice fields are considred major sources of methane (CH4) omission. The source strength of CH4 from rice field is very uncertain and this uncertainty may further increase under changing climatic conditions, e.g. with increasing global temperature. Pot experiment in walk-in growth chamber with controlled day and night temperatures was conducted in International Rice Research Institute (IRRI), Philippines to determine the influence of increasing temperature on the source strength of methane in paddy rice soils (Aquandic Epiaquoll). Three levels of temperature i.e., 29/22, 32/25 and 35/28 deg C representing daily maxima/minima with two levels of rice straw (0 ton/ha and 6 ton/ha) were arranged in complete randomized design (CRD) with four replications. The elevated temperature with rice straw application affects soil redox potential, methane emission and rice yield were examined. The hypothesis increased temperature with rice straw application could decrease the soil redox potential faster and increase CH4 emission, was tested. The monitoring of soil redox potential and CH4 emission was done weekly throughout the rice growing period. Higher temperatures increased methane emission rates throughout the growth period of rice. However, the increment in emission triggered by higher temperature was especially prominent after incorporation of rice straw. Decrease reducation potential to less than -100 mV and methane emission was observed after 60 days of rice transplanting in pots without rice straw while it was observed after 14 days in rice straw treated pots. Significantly higher total CH4 emission was observed with high (35/28 deg C) temperature with rice straw application. Moreover, high temperature significantly increased spikelet sterility and reduced grain yield (P0.05) of the rice.
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