RESUMO
In order to evaluate the effect of different treatments on yield and greenhouse gas emissions during the summer maize growing season, a two-year film mulching experiment was conducted in 2014 and 2015. In this experiment, the two main experimental factors were rainfed treatment (R) and irrigated treatment (I), and the secondary experimental factors included control treatment (CK), half film mulching treatment (HM), and full film mulching treatment (FM). The emissions of soil greenhouse gases (CO2, CH4, and N2O) were monitored using a static opaque chamber and chromatography method. Moreover, the greenhouse gas emissions intensity (GHGI) was used to evaluate the effect of carbon sequestration in different treatments. The results of this study showed that the yields of the RHM and RFM treatments did not differ significantly in 2014, but increased by 19.6% and 26.8%, respectively, in 2015 compared with that of RCK. The yield of IHM was not improved, and that of IFM significantly increased by 14.1% and 55.8% in 2014 and 2015, respectively, compared with that of ICK. The irrigated treatments only promoted CO2 emissions in 2015 (P<0.01), and all film mulching treatments (regardless of HM and FM treatments) had no effect on CO2 emissions under rainfed and irrigated conditions (P>0.05). Irrigated treatments had no effect on the absorption of CH4 (P>0.05), whereas the film mulching treatments had an inhibitory effect. Compared with values of RCK, the amount of seasonal N2O emissions for ICK showed a significant difference in 2015 with a decrease of 22.3%. Compared with values of RCK, the amounts of N2O emissions for RHM and RFM had no significant differences in 2014, but significantly decreased by 50.7% and 51.4% in 2015, respectively. Compared with ICK, IHM and IFM significantly decreased the amounts of N2O emissions by 47.5% and 54.2% in 2014, and by 9.6% and 52.2% in 2015, respectively. The GHGIs of RHM and RFM were significantly reduced by 60.1% and 61.7% in 2015, respectively, compared with values of RCK, and the GHGIs of IHM and IFM were significantly reduced by 39.7% and 53.2% in 2014, and reduced by 22.2% and 67.5% in 2015, respectively, compared with that of ICK. This means that the effect of FM on reducing GHGI was better than that of HM. It was also found that the significantly reduced GHGI in irrigated treatments may be attributed to the increased yields. Therefore, FM under irrigation conditions was recommended for summer maize for stabilizing the yield and reducing the GHGI.
