Evaluation of methane and nitrous oxide emissions in a three-year case study on single rice and ratoon rice paddy fields

Abstract

Ratoon rice involves the production of a second crop after the previous main crop harvest, originating from the remaining stubble. Plastic film mulching (PM) cultivation is considered a promising technique for improving economic benefits and reducing greenhouse gas intensity (GHGI). However, the effects of the different cultivation practices differences on the GHGI and the net ecosystem economic budget (NEEB) remain unclear. A three-year experiment was performed to measure CH4 and N2O emissions and grain yields, and then comprehensively assess the GHGI and NEEB. Four rice cropping treatments were established in a traditional single rice field: continuously flooded (CF), rainfed (RF), PM, and PM with ratoon rice cultivation (PM + RR). Compared with CF, RF increased N2O emissions by 108% and reduced CH4 emissions and grain yield by 75% and 22%, respectively, resulting in a reduction of NEEB by 1396 CNY ha−1 y−1. Switching from CF to PM, however, decreased annual CH4 emissions by 56% and increased N2O emissions by 358%, resulting in a 51% reduction in GHGI and an 883% increase in NEEB. Under PM, RR further reduced GHGI by 12% and increased NEEB by 18%. Compared with CF, PM + RR not only significantly increased crop yield by 1.32 t ha−1 and NEEB by 4410 CNY ha−1 y−1, but also dramatically decreased GHGI by 57%. These findings indicate that planting ratoon rice under PM can improve NEEB and reduce GHGI, potentially leading to a win-win situation for the environment and growers in water-stressed regions.