Effects Of Water-saving Irrigation And Conservation Tillage On Cropping Growth And Greenhouse Gases Emissions In Double Rice-Cropping Systems

Conservation tillage and water-saving irrigation on cropping yield and greenhouse gas emissions has significant influence in double rice-cropping systems, we not only need consider the global warming potentials of various greenhouse gases, but also took the crop yield into account when we need to evaluate the potential impact of agricultural management practices on global climate change. This experiment used of static chamber gas chromatography and the double cropping-milk vetch was studied in Jiangxi red soil regions. Across positioning experiment research of water-saving irrigation and conservation tillage on the impact of Cropping growth and development and greenhouse gas emissions in double Rice-cropping systems. The three water regime treatments included continuous flooding（F）, flooding-midseason drainage-flooding（F-D-F） and flooding-midseason drainage-flooding-moist intermittent irrigation（F-D-F-M） in rice growing seasons. Conservation tillage research from the viewpoint of tillage methods and straw returned, the tillage treatments included conventional tillage（CT）, rotary tillage（RT） and no-tillage（NT）. Straw returned treatments set straw returned（SR） and the straw to remove（SM）. The main research results are as follows（1） Water-saving irrigation and conservation tillage effects on rice growth and developmentUnder the different of water management treatments, the rice yield of F-D-F and F-D-F-M treatments is more than F except for the late rice season in 2013. But there was no significant difference in the yield of different treatments. To Compared with F, the main reason of high yield is the effective panicles number of medium and more grain number per panicle under water-saving irrigation.The anniversary rice yield show that RT > CT > NT under different tillage treatments, but there was no significant difference in different treatments. To compare with CT, more effective panicle number and1000-grain weight Increase is main reason for RT to reach the higher rice yield, but the NT treatment reduction of output is because of less effective panicle number and the grain number per panicle.The rice yield of SR treatment is greater than the SM treatment in the double Rice-cropping systems under the Straw returned treatments, but there was no significant difference in rice yield. To compare with SM, More grain number per panicle and Filled grain ratio bigger is the main reason for the SR treatment to reach the higher yield.（2） The influence of Water-saving irrigation on paddy greenhouse gas emissionsVarious treatments CH₄ emissions are based on the rice planting season under different Water regime treatments, and the rice planting season accounted for 99.72%-99.95% of annual CH₄ accumulated emissions. The N2 O emissions mainly comes from the milk-vetch growing season, and the milk-vetch growing season accounted for 39.7%-72.5% of annual N2 O accumulated emissions. GWP of all treatments was 7648.8-23132.7 kg CO₂-eq kg-1 hm-2,GHGI was 0.48-1.39 kg CO₂-eq kg-1 grain yield. To compare with F, GWP and GHGI of F-D-F and F-D-F-M are significantly reduced. Therefore, to compare with F, F-D-F and F-D-F-M can significantly slow down the global warming potentials in the paddy fields.（3） The influence of tillage methods on paddy greenhouse gas emissionsVarious treatments CH₄ emissions are based on the rice planting season under different tillage treatments, and the rice planting season accounted for 99.10%-99.81% of annual CH₄ accumulated emissions. The N2 O emissions mainly comes from the milk-vetch growing season, and the milk-vetch growing season accounted for 53.88%-65.22% of annual N2 O accumulated emissions.GWP of all treatments was 9082.8-14775.4 kg CO₂-eq kg-1 hm-2,GHGI was 0.55-0.83 kg CO₂-eq kg-1 grain yield. To Compared with CT, GWP and GHGI of NT treatment significantly reduced 35.70% and 33.07% respectively, On the contrary, GWP and GHGI of RT treatment increased by 4.60% and 2.06% respectively, But there was no significant difference. Therefore, to compare with CT, NT can significantly reduce the paddy greenhouse gas emissions, and RT can increased paddy greenhouse gas emissions.（4）The influence of straw returned on paddy greenhouse gas emissionsVarious treatments CH₄ emissions are based on the rice planting season under straw returned, and the rice planting season accounted for 98.80%- 99.79% of annual CH₄ accumulated emissions. The N2 O emissions mainly comes from the milk-vetch growing season, and the milk-vetch growing season accounted for 15.12%-54.26% of annual N2 O accumulated emissions. GWP of all treatments was 8020.1-1463.5 kg CO₂-eq kg-1 hm-2,GHGI was 0.49-0.82 kg CO₂-eq kg-1 grain yield. To Compared with SM, SR treatment with GWP and GHGI significantly increased by 76.1% and 76.1% respectively. Therefore, to compare with SM, SR significantly increased the paddy greenhouse gas emissions.To sum up, Water-saving irrigation and conservation tillage had no significant influence in cropping yield, but it was significant influence on the global warming potentials in double rice-cropping systems. Straw returned can lead to CH₄ emissions increased significantly, but through no-tillage and water-saving irrigation can effectively slow down GWP and GHGI of the paddy fields. Therefore, adopt water-saving irrigation under conservation tillage measures can achieve double effect of high and stable yield crop and reduction of greenhouse gas emissions.