The Effect Adding Earthworms To Soil On Microbial Functional Diversity During The Straw Return Process

Corn Straw is a common renewable resource in the Northeast China and contains rich nutritional elements.Earthworms have an impact on the activity of soil microorganisms through activities such as digging,feeding,and excreting dung,thus changing the community structure and function of soil microorganisms.Soil microorganisms are important biological indicators for evaluating soil ecological functions and participated in several important soil processes,including nutrient transport,energy flow,and organic matter decomposition.The addition of earthworms to the straw return process can increase the storage of carbonaceous substances in the soil,and provide nutrients for the life activities of soil microorganisms,thus creating favorable conditions for the growth and reproduction of microorganisms,in addition to having an impact on the functional diversity of soil microorganisms.In this paper,a straw return experiment was carried out in the farmland of Yangjialu,Dehui City,Jilin Province.Four treatments were set up in the experiment: control treatment(CK),straw only(S),earthworm only(E),and straw and earthworm at the same time(SE).Soil samples were collected in May,July and September of 2021.The functional diversity of soil microorganisms under different treatments was measured by the biolog microplate method.Analysis of the relationship between microbial functional diversity characteristics,soil physicochemical properties,and enzyme activity,under different treatments to explore the effect of adding earthworms on the functional diversity of soil microorganisms in the process of straw return.The main results are as follows:(1)The addition of earthworms in straw returning process is beneficial to the improvement of soil microbial metabolic activity,and the change of microbial metabolic activity shows a trend of increasing first and then stable.All treatments can improve the Shannon diversity index,Simpson dominance index and Pielou evenness index of soil microorganisms.The Mc Intosh index of each treatment is significantly higher than that of the control only in July.(2)The main types of carbon sources utilized by the different treatment microorganisms are carbohydrates and amino acids.In terms of the utilization capacity of single carbon source,soil microorganisms with earthworms and straw added at the same time has the strongest utilization capacity of carbon source,and soil microorganisms with different treatments has significant differences in carbon source utilization capacity.(3)The addition of earthworms in straw returning can increase the activities of soil catalase,urease,phosphatase and sucrase.There are significant differences in soil enzyme activities under different treatments.There are significant differences in soil enzyme activities at different sampling times.(4)The correlation analysis between soil physical and chemical properties and microbial functional diversity showed that soil p H and organic matter were the key environmental factors affecting microbial functional diversity.The correlation analysis between soil enzyme activity and microbial functional diversity showed that soil catalase and urease would have a significant impact on microbial functional diversity.In summary,adding earthworms to the straw return process can improve soil physicochemical properties,enhance soil enzyme activity,improve soil fertility levels and increase the content of nutrients required for soil microbial growth,and enhance the functional diversity of soil microorganisms.In this study,the metabolic activity and carbon source utilization of soil microorganisms and changes in soil microenvironment and its ecological functions are thoroughly investigated to provide theoretical support for the rational utilization of straw resources.