Release of entrapped methane from wetland rice fields upon soil drying
- Agricultural Univ., Wageningen (Netherlands)
- International Rice Research Institute, Los Banos (Philippines); and others
Methane emissions from rice paddies were monitored to determine the dynamics of methane release during evaporative drying. Two clay soils and one calcareous sandy loam, all from Philippine rice paddies, were examined. The soils were fertilized with urea or green manure, and/or amended with gypsum. Monitoring data was collected for several weeks after harvesting 1992 dry and wet season crops. Methane emission was monitored automatically with a closed chamber technique using 24-hour semincontinuous determination of methane emission rates from different gas collector chambers. In all plots, very high emissions of methane to the atmosphere during the early phase of soil drying was observed. It was not determined whether this was due to the drainage method or partly attributable to low time resolution sampling. The total amount of methane emitted depended on the fertilizer and/or soil amendment. However, the ratio of the methane released during evaporative drying and methane emitted during the growing seasons was approximately constant. Therefore, methane during soil drying is a significant component of the total methane emitted from a rice paddy. Neglecting this component could cause total methane emission during a rice crop cycle to be underestimated by about 10 percent. 14 refs., 4 figs., 3 tabs.
- OSTI ID:
- 244049
- Journal Information:
- Global Biogeochemical Cycles, Vol. 10, Issue 1; Other Information: PBD: Mar 1996
- Country of Publication:
- United States
- Language:
- English
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