Effects of rice stalk mulching combined with green manure retention and nitrogen reduction on rice yield and ammonia emission
A field experiment was conducted in Hanzhong,Shaanxi Province for two consecutive rotation seasons(2019-2021)to study the integrated effect of milk vetch(Astragalus sinicus L.)and rice(Oryza sativa L.)straw return with nitrogen reduction on rice yield and ammonia volatilization in milk vetch-rice rotation system.The four treatments were:no returning of rice straw in winter accompanied by conventional N application,namely,control(CK);co-incorporation of Chinese milk vetch and rice straw in winter accompanied by conventional N application(GRN100);reducing 20%of N application rate based on the GRN100(GRN80);and reducing 30%of N application rate based on the GRN100(GRN70).A ventilation NH3 volatilization collection device monitored the characteristics of ammonia(NH3)volatilization during the rice growth periods.The results showed that:compared with the CK,the co-incorporation of Chinese milk vetch and rice straw in winter increased the grain yield of Huanghuazhan in the order of GRN80>GRN70>GRN100.In particular,the average annual increase of GRN80 and GRN70 was 7.66%and 6.37%,respectively,relative to the CK.The NH3 volatilization in the canopy mainly occurred after 30 days of fertilization,with a higher rate in the periods from the heading to maturity stage.The soil NH3 volatilization occurred mainly within 16 days after fertilization and peaked on the second day after fertilization,which was 0.53 kg·hm-2·d-1 and 0.58 kg·hm-2·d-1 in 2020 and 2021,respectively.Compared with the CK,the GRN80 significantly reduced both the accumulation value and intensity of canopy NH3 volatilization by 58.73%and 57.14%,respectively,during the entire rice growth period.The accumulation value and intensity of soil NH3 volatilization were also significantly reduced under the co-incorporation of Chinese milk vetch and rice straw in winter during the whole rice growth periods relative to the CK,with the order of GRN100>GRN70>GRN80.In terms of the accumulation value and intensity of NH3 volatilization during the entire rice growth period,compared with the CK,the co-incorporation of Chinese milk vetch and rice straw in winter significantly reduced them by 2.88%-8.32%and 5.26%-13.88%,respectively,with the highest reduction rate under the GRN80.Correlation analysis showed that the NH+4-N concentration in surface water was significantly positively correlated with soil NH3 volatilization rate under every treatment,while it was significantly negatively correlated with the canopy NH3 volatilization rate under GRN80 and GRN70.The research shows that the co-incorporation of Chinese milk vetch and rice straw in winter accompanied by reducing 20%or 30%N application rate based on the conventional N application rate,can significantly increase rice yield and reduce NH3 volatilization.It thus may be a suitable rice cultivation strategy for high grain yields and environmental friendliness.
Chinese milk vetch-rice rotationstraw returnnitrogen reductionrice grain yieldammonia volatilization
万方数据
维普
