| Aiming at the problems of poor soil environment and uneven seasonal distribution of climate resources in the red soil dryland farmland ecosystem,In this study," Chinese milk vetch-spring corn-autumn soybeans" was used as a control,and four different intercropping multi-cropping systems were set up: "potato-spring corn||spring soybeans-buckwheat" 、 "Mixed Sowing of ’Three Flowers’-Spring Corn||PeanutsSesame||Mung Beans","Broad Beans-Spring Corn/Spring Sweet Potatoes","RapeSpring Corn||Spring Soybeans-Summer Sweet Potatoes||Mung Beans".Focus on exploring the effects of different multi-crop planting systems on soil chemical properties,soil organic carbon pool and microbial communities.Study the distribution of light,heat and water resources and their contribution to system productivity.Reveal the mechanism of multi-cropping planting system to improve the soil environment of red dry land and efficiently use climate resources.Analyze the comprehensive benefits of the multi-cropping planting system by using the gray correlation method,and select the high-yield and high-efficiency multi-cropping planting system suitable for the red dry land,and provide theoretical support for the establishment of a suitable planting model for the efficient use of red soil dry land resources.The main conclusions are as follows:(1)The annual total biomass of the "broad bean-spring corn/spring sweet potato" planting system is the highest,which is 41.87% higher than that of the "Chinese milk vetch-spring corn-autumn soybean".The intercropping and multi-cropping system has higher annual productivity and net output value.(2)The allocation rate of light and hot water resources in the "Rape-Spring Corn||Spring Soybean-Summer Sweet Potato||Mung Bean" planting system is higher than that of the ""Chinese milk vetch-spring corn-autumn soybean".The light energy production efficiency,effective accumulated temperature production efficiency and precipitation production efficiency of the four intercropping and multi-cropping planting systems are all higher than "Astragalus vulgaris-spring corn-autumn soybeans".The "broad bean-spring corn/spring sweet potato" planting system has the highest light energy utilization rate and precipitation apparent bioavailability,which is significantly higher than that of "Chinese milk vetch-spring corn-autumn soybeans".Intercropping and multi-cropping planting systems have great potential in the efficient use of climate resources.(3)The crop diversity index of the intercropping and multi-cropping system with richer and more varieties of crops is higher.The higher crop diversity index is "threeflower mixed-spring corn||peanut-sesame||mung bean",and the lower one is "broad bean-spring corn/spring sweet potato".(4)Intercropping and multi-cropping planting systems have great potential in improving soil acidic environment,promoting the accumulation of soil available phosphorus,soil total organic carbon,soluble organic carbon,soil microbial biomass carbon content,and increasing soil microbial entropy and soil carbon pool index.(5)"Broad bean-spring corn/spring sweet potato" has the highest abundance and diversity of soil bacteria and fungi microbial communities.The bacterial microbial community abundance of this planting system was significantly higher than that of"three-flower mixed planting-spring corn||peanut-sesame||mung bean",and the diversity of fungal microbial community was extremely significantly higher than that of "Chinese milk vetch-spring corn-autumn soybean"(P<0.01).The fungal microbial community diversity of "three-flower mixed sowing-spring corn||peanut-sesame||mung bean" was significantly higher than that of ""Chinese milk vetch-spring corn-autumn soybean"(P<0.05).The soil microbial abundance and diversity of the intercropping and multi-cropping system is higher.(6)Soil carbon pool is more related to soil nitrogen nutrients.Soil nitrate nitrogen was significantly positively correlated with soil microbial biomass carbon(P<0.05),and soil ammonium nitrogen was significantly positively correlated with total organic carbon and soil microbial biomass carbon(P<0.01).Soil nutrients affect the distribution of soil fungi and bacterial communities.From the perspective of soil chemical properties,the composition of soil bacterial and fungal microbial communities in dry land of red soil is closely related to soil nitrogen nutrients.The activities of soil microorganisms may affect the changes of soil carbon pool components and soil nitrogen and other nutrients.(7)The comprehensive benefit evaluation of five multi-cropping planting systems was carried out using the grey correlation method.The one with higher ecological benefit is "rape-spring corn||spring soybean-summer sweet potato||mung bean".The intercropping and multi-cropping planting system with better comprehensive benefits was initially selected as "broad bean-spring corn/spring sweet potato",which has higher economic and social benefits. |
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