Differences in rice yield and CH4 and N2O emissions among mechanical planting methods with straw incorporation in Jianghuai area, China

•Dry direct-seeding reduced CH4 emission significantly with a comparable yield.•No significant difference in N2O emission was found between the planting methods.•Straw recycling did not increase CH4 emission under mechanical dry direct-seeding.•Lowest area- and yield-scaled emissions were found in dry direct-seeding fields.

Mechanical planting is replacing manual transplanting in the major Asian rice cropping areas, however, few are known about the impacts of mechanical planting on rice yield and greenhouse gas (GHG) emission. Therefore, a two-year experiment was conducted to examine the impacts of dry direct-seeding (MDS), wet direct-seeding (MWS) and transplanting (MTP) in Jianghuai area, China. The results showed that CH4 emission was significantly lower in the MDS than the MWS and MTP both with and without straw incorporation. No significant difference in N2O emission was found among the planting methods. Straw incorporation significantly stimulated CH4 emission in the MWS and MTP, but not in the MDS. The lowest rice yield was found in the MWS, while there was no significant difference in grain yield between the MDS and MTP methods. The area-scaled emission of CH4 and N2O in CO2-equivalent unit was respectively 78.5 and 89.6% lower in the MDS than those in the MWS and MTP without straw incorporation, and 87.7 and 94.1% lower with straw incorporation. The yield-scaled emission was correspondingly 80.4 and 88.1% lower without straw incorporation, and 89.0 and 93.4% lower with straw incorporation, respectively. Our results indicate that MDS can get an acceptable yield with a large reduction in GHGs emissions in the test location.