Effect of controlled drainage in the wheat season on soil CH4 and N2O emissions during the rice season

The effect of draining crop fields during the wheat season on the soil CH4 and N2O emissions during the rice season in this article. There were four treatments: traditional cultivation during the wheat season + cultivation without fertilization during the rice season (CK1 field), traditional cultivation during the wheat season + traditional cultivation during the rice season (CK2 field), draining the fields through shallow furrows + traditional cultivation during the rice season (CQ field) and draining the fields through deep furrows + traditional cultivation during the rice season (CS field). The results are listed as follows. (1) Draining the field through furrows during the wheat season significantly reduced the CH4 and N2O emissions during the rice season. Compared with the CK1 field, the total CH4 emissions from the CQ and CS fields decreased by 43.1% and 39.9%, respectively; compared with the CK2 field, the total CH4 emissions from the CQ and CS fields decreased by 58.1% and 55.7%, respectively; compared with the CK2 field, the total N2O emissions from the CQ and CS fields decreased by 33.6% and 32.7%, respectively. N2O emissions from the CQ and CS fields caused by fertilization declined by 44.0% and 42.9% compared with that from the CK2 field. (2) Draining the wheat field in winter changed the CH4 emission pattern during the following rice season. The daily average CH4 emission flux from the winter flooded CK1 and CK2 fields were comparable before the field sunning and after the re-flooding and the fluxes from the drained CQ and CS fields before the field sunning were close to that from the CK1 and CK2 fields but were significantly greater than that from the drained CQ and CS fields after the field re-flooding. (3) The soil CH4 emission flux was significantly negatively correlated to the soil Eh. But the correlation was weakened by the drainage treatment in the wheat season. In summary, draining the crop field in the wheat season should be an effective approach to reducing soil greenhouse gas emissions in the rice season.