| A reasonable planting system can not only improve crop yield,save costs and increase income,achieve high yield and efficiency in rice field production,but also promote agricultural ecological cycle,stabilize soil fertility,maintain food security,agricultural ecological security,and promote sustainable agricultural development.In order to explore ecological and environmental friendly planting patterns suitable for the promotion of double cropping rice areas in the middle reaches of the Yangtze River,this study set up five planting modes,namely,Chinese milk vetch-early rice-late rice(CRR,CK),Chinese milk vetch-early rice-sweet potato | | soybean(CRI),rape-early rice-late rice(RRR),rape-early rice-sweet potato | | soybean(RRI)and potato-early rice-late rice(PRR),to study the characteristics of crop yield,soil physical and chemical properties,soil organic carbon and components,soil microbial community structure diversity,and soil enzyme activity under the three cropping system in the double cropping rice region of the middle reaches of the Yangtze River,and the comprehensive benefit analysis of five planting modes was conducted.The main research results are as follows:(1)Chinese milk vetch-early rice-sweet potato | | soybean(CRI),rape-early rice-sweet potato | | soybean(RRI),and rape-early rice-late rice(RRR)models all significantly improved crop yields.Compared to the control,the rape-early rice-sweet potato | | soybean model significantly increased late rice yield and total yield by 31.43%and 27.39%(P<0.05),respectively.(2)Chinese milk vetch-early rice-sweet potato | | soybean(CRI)can improve soil macro-aggregate content and soil stability.Compared with the control,the soil aggregate content of CRI>2 mm increased by 20.77%,6.71% and 2.19% during winter and early and late rice harvest periods,respectively.After two years of testing,the p H value of each treatment increased,and the rape-early rice-late rice(RRR)model performed best;The soil organic matter and total nitrogen content of the Chinese milk vetch-early rice-sweet potato | | soybean(CRI)model was the highest,with increases of 7.89%～35.02% and6.59% ～ 26.80% compared to other treatments.The soil available phosphorus and potassium contents of the potato-early rice-late rice(PRR)model were higher than those of other treatments,with increases of 29.48% and 126.49% compared to the control.Chinese milk vetch-early rice-sweet potato | | soybean(CRI)and rape-early rice-sweet potato | | soybean(RRI)models were beneficial to improving the soil nitrate and ammonium nitrogen contents.(3)The rape-early rice-late rice(RRR)model is beneficial to the accumulation of soil organic carbon and can slow down the loss of soil carbon.The models of Chinese milk vetch-early rice-sweet potato | | soybean(CRI)and rape-early rice-sweet potato | |soybean(RRI)are beneficial to improving the content of soil soluble organic carbon.(4)Chinese milk vetch-early rice-sweet potato | | soybean(CRI)and rape-early rice-late rice(RRR)are beneficial to improving the microbial diversity index.Proteobacteria,Curvularia,and Actinomycetes are the top three dominant groups of soil bacteria with relative abundance,while the top three dominant groups of soil fungi are Ascomycetes,Basidiomycetes,and Mucor.The pattern of Chinese milk vetch-early rice-sweet potato | | soybean(CRI)and rape-early rice-sweet potato | | soybean(RRI)increased the relative abundance of soil actinomycetes and ascomycetes.Ammonium nitrogen,total organic carbon,nitrate nitrogen,and available phosphorus are the main environmental factors that affect the structure of soil microbial communities.(5)Compared with the control,the Chinese milk vetch-early rice-sweet potato | |soybean(CRI)and rape-early rice-sweet potato | | soybean(RRI)models significantly increased soil invertase and urease,with increases of 11.4% ～ 13.16% and 84.44% ～168.15% during the late rice harvest period.Potato-early rice-late rice(PRR)treatment was beneficial to improving soil catalase activity.(6)The economic benefits of the rape-early rice-late rice(RRR)planting model are the highest,while the ecological benefits of the Chinese milk vetch-early rice-sweet potato | | soybean(CRI)planting model are better.rape-early rice-late rice(RRR)and rape-early rice-sweet potato | | soybean(RRI)have better social and comprehensive benefits.To sum up,in the double cropping rice region in the middle reaches of the Yangtze River,taking into account crop yield and economic benefits,the rape-early rice-late rice planting model performs best,with the highest comprehensive benefits,and has the advantage of sustainable development,which is conducive to alleviating the food crisis and promoting high-quality agricultural development.In the seasonally arid region of the middle reaches of the Yangtze River,taking into account soil fertility and ecological benefits,it has a good prospect to appropriately develop the Chinese milk vetch-early rice-sweet potato | | soybean and rape-early rice-sweet potato | | soybean cultivation models. |
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