Beijing Study Points Out Way To Cut Methane Emissions
Chinese scientists have conducted a study regarding the production of the potent greenhouse gas methane in flooded rice fields. Rice is one of the major food crops for the world and many hectares are devoted to the growing of it, much of it in flooded fields or paddies. Rice straw left to rot in the flooded fields is decomposed by anaerobic bacteria that produce methane as a by-product. This represents a significant contribution to the earth's load of greenhouse gases.
The team says that if draining is combined with applying rice straw — the stem and leaves left behind after harvesting — methane emissions could be reduced by 7.6 million tonnes a year, representing around 30 per cent of global emissions from rice fields.
Rice straw is traditionally either burned between growing seasons or ploughed back into the soil as a source or nutrients for the next season's crop. When the field is reflooded, microorganisms feeding on the rice straw generate methane.
But if the straw is left to decompose in the open air of a drained field during the fallow season, methane emissions would be reduced, say Yan and his colleagues, and the rice straw could still supply some nutrients to the soil.
The technique has yet to be tested on farmers' rice fields, but the results from the experimental ones are promising.
Stanley Tyler from the US-based University of California, Irvine, told SciDev.Net: "Flooded and rain-fed rice paddies are one of the few wholly man-made methane sources and potentially one of the best chances for humans to control methane emissions."