Rice paddies produce an estimated 20% of the methane released by human activities. But according to data presented at a Beijing climate conference last week, a switch to certain farming practices could erase most of those emissions. Jane Qiu reports on the research over at Nature News.
Earlier this year, Xiaoyuan Yan of the Chinese Academy of Sciences and colleagues came out with a notably low estimate of global rice-paddy methane emissions. Unlike other surveys, this one took into account the methane-busting practices of draining paddies mid-season and applying rice straw between crops.
Qiu’s story highlights work from a different American-Chinese team – Chris Butenhoff and Aslam Khalil of Portland State University and Xiong Zhenqin of Nanjing Agricultural University. Mid-season paddy draining has been common in China since the 1980s, the group points out, because it increases rice yield and saves water. By looking at the spread of paddy-draining and straw-strewing practices and at experiments that show the effects of such techniques, the researchers estimate that methane emissions from Chinese paddies have fallen nearly 70% from 1980 levels.
The catch? Drained paddies emit more nitrous oxide, another potent greenhouse gas. Still, the net effect is equivalent to taking 270 million tonnes of carbon dioxide out of the atmosphere annually. But outside China, mid-season drainage is not commonly practiced. Low-hanging fruit, anyone?