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Methane emissions and mitigation options in irrigated rice fields in southeast China

: Lu, W.F.; Chen, W.; Duan, B.W.; Guo, W.M.; Lu, Y.; Lantin, R.S.; Wassmann, R.; Neue, H.U.


Nutrient cycling in agroecosystems 58 (2000), Nr.1/3, S.65-73
ISSN: 1385-1314
Fraunhofer IFU; 2002 in Helmholtz-Gesellschaft integriert
midseason drainage; pig manure; rice straw; biogas residual; cultivar; winter fallow; dissolved methane

Methane (CH sub 4) emissions from rice fields were monitored in Hangzhou, China, from 1995 to 1998 by an automatic measurement system based on the "closed chamber technique." The impacts of water management, organic inputs, and cultivars on CH sub 4 emission were evaluated. Under the local crop management system, seasonal emissions ranging from 53 to 557 kg CH sub 4 ha high -1 were observed with an average value of 182 kg CH sub 4 ha high -1. Methane emission patterns differed among rice seasons and were generally governed. by temperature changes. Emissions showed an increasing trend in early rice and a decreasing trend in late rice. In a single rice field, CH sub 4 emissions increased during the first half of the growing period and decreased during the second half. Drainage was a major modifier of seasonal CH sub 4 emission pattern. The local practice of midseason drainage reduced CH sub 4 emissions by 44 % as compared with continuous flooding; CH sub 4 emissions could further be reduced by intermittent irrigation, yielding a 30 % reduction as compared with midseason drainage. The incorporation of organic amendments promoted CH sub 4 emission, but the amount of emission varied with the type of organic material and application method. Methane emission from fields where biogas residue was applied was 10 - 16 % lower than those given the same quantity (based on N content) of pig manure. Rice straw applied before the winter fallow period reduced CH sub 4 emission by 11 % as compared with that obtained from fields to which the same amount of rice straw was applied during field preparation. Broadcasting of straw instead of incorporation into the soil showed less emission (by 12 %). Cultivar selection influenced CH sub 4 emission, but the differences were smaller than those among organic treatments and water regimes. Modifications in water regime and organic inputs were identified as promising mitigation options in southeast China.