[Comprehensive effects of combined application of organic and inorganic fertilizer on yield, greenhouse gas emissions, and soil nutrient in double-cropping rice systems].

We carried out a 3-year field experiment with three treatments: 1) no fertilizer application (CK), 2) chemical fertilizer application (F), and 3) combined organic and chemical fertilizer (FM) in which the total nitrogen inputs were equal with F (organic fertilizer applied in the early rice season). We evaluated the variations of crop yield, CH4 and N2O emission, and soil nutrient. The results showed that fertilizer application could increase rice yield in both early and late rice seasons. Compared with F treatment, FM treatment increased rice yield by 5.6% and 7.2% for early and late rice, respectively. The enhancement of yield was positively correlated with years. Compared with F treatment, CH4 emission in early rice season, late rice season and whole year in the field in FM treatment was increased by 8.2%, 4.8% and 6.7%, respectively, while the N2O emission was deceased by 31.4%, 5.0% and 18.8%, respectively. Organic fertilizer application reduced the greenhouse gas intensity (GHGI) by 6.8% and 8.5%, but there was no significant differences in global warming potential (GWP) across treatments in 2018 and 2019. Compared with F treatment, the content of organic matter, total nitrogen, available phosphorus and available potassium were increased by 9.7%, 4.1%, 30.9% and 2.5%, respectively. Overall, our results suggested FM application in early rice season is an effective measure to increase crop yield, improve soil nutrient, and reduce GHGI.