Abstract
Experiments were conducted to examine the effect of continuous application of different kinds of straw on methane emission and production in flooded rice soil microcosms. Consecutive cultivation for four years revealed that there was no significant difference in the amounts of methane emitted by plots applied with rice straw and those applied with wheat straw, though emissions varied remarkably from year to year. Methane emission from plots with an application of 6t ha-1 rice straw or wheat straw increased 3.5 times or 3.4 times compared to that from plots without straw, respectively. Continuous application of straw altered the methanogenic characteristics by increasing the response to glucose added to the soil. The production potential of methane and carbon dioxide was measured by laboratory incubation, and was significantly increased in samples taken from plots receiving straw applications when glucose was added, while there was no response to glucose addition in soil from plots without straw application. In contrast, dissolved carbon including organic acids were accumulated in the control plot. These results indicated that the methane production potential in response to glucose was maintained by continuous application of straws.
