Suppression of CH4 Emission by Rice Straw Removal and Application of Bio‐Ethanol Production Residue in a Paddy Field in Akita, Japan

To elucidate the effects of rice straw removal and rice straw‐based bio‐ethanol production residue application on rice growth and methane (CH4) emission from a paddy field, a lysimeter experiment with three treatments (application of rice straw after harvesting (the rice‐straw plot); removal of rice straw and the application of bio‐ethanol production residue (the Et‐residue plot); removal of rice straw (the no‐application plot)) was conducted over three years. Though the grain yields in the Et‐residue and no‐application plots tended to be slightly higher than that in the ricestraw plot, there were no significant differences among the plots (530–546 g∙m−2). Suppression of CH4 emission by the treatments was found clearly in the early part of the growing season. The total CH4 emissions during the rice‐growing season (unit: g∙C∙m−2∙period−1) followed the order of the noapplication plot (11.9) < the Et‐residue plot (14.6) < the rice‐straw plot (25.4), and a significant difference was found between the no‐application and rice‐straw plots. Consequently, bio‐ethanol production from rice straw and a following application of its residue to paddy fields is considered to be a promising technology which can obtain new sustainable energy and suppress CH4 emission without any inhibition on rice growth.