Effects Of Different Agricultural Activities On The Characteristics Of Surface Soil Fauna Community In Huang-huai-hai Region

Farmland ecosystem is the basis of human survival and development,which is of great significance to the sustainable development of human beings.The Huang-Huai-Hai region is one of the important grain production bases in China.Its agricultural activities are mainly based on the application of chemical fertilizers,supplemented by agricultural means such as organic fertilizers or straw returning,so as to achieve the purpose of increasing grain production.Soil organisms are an important component of farmland ecosystem and have extremely important ecological functions.Soil fauna have a large number of groups and constitute a complex soil food web with soil microorganisms.Exploring the effects of major agricultural activities such as fertilization on the characteristics of soil fauna communities is of great significance for optimizing farmland management measures and maintaining soil health.This study was conducted at five long-term research stations of agriculture ecosystems（Hengshui,Laiyang,Yuanyang,Xuzhou and Mengcheng）,which are located in the Huang-Huai-Hai region.This study explored the effects of representative agricultural activities,i.e.,inorganic fertilization,organic fertilization,straw returning to the field,inorganic fertilization combined with organic fertilization,inorganic fertilization combined with straw returning to the field,and land abandonment,on the characteristics of soil fauna community.The main results are as follows:（1）Different agricultural activities mainly affected the abundance of Entomobryidae,Isotomidae,Formicidae,Lycosidae,Staphylinidae and Carabidae to change the community structure of soil fauna.Straw returning significantly increased the density of herbivorous soil fauna functional groups,and inorganic fertilizer plus straw returning significantly increased the predatory soil fauna functional groups.（2）Fungi and G+were sensitive to agricultural activities.Soil microorganisms also affected soil fauna communities to some extent.The abundance of soil fauna functional groups in Detritivore and Herbivore was negatively correlated with Fungi.The abundance of soil fauna functional groups in Omnivore was negatively correlated with BSI.The advantage of fungal channel in farmland ecosystem is obvious,and the feeding effect of soil fauna on fungi may lead to the decrease of fungal biomass.（3）Agricultural activities have changed the physical and chemical environment of farmland.Among them,agricultural activities tend to increase soil organic carbon（SOC）,soil total nitrogen（TN）,soil available phosphorus（Olsen P）,available potassium（AK）,ammonium nitrogen（NH₄⁺）,nitrate nitrogen（NO₃^-）.The application of inorganic fertilizer,organic fertilizer and straw returning had significant negative effects on soil bulk density（BD）and soil（p H）,while farmland abandonment tended to increase soil（p H）.Soil fauna communities were affected by environmental factors such as site,temperature（T）,soil（p H）,total potassium（TK）,soil available phosphorus（Olsen P）,and soil nitrate nitrogen（NO₃^-）.（4）The yield of farmland may be affected by Detritivore and Omnivore soil fauna functional groups..There was a significant positive correlation between soil fauna and farmland yield in Detritivore and Omnivore.In summary,different agricultural activities such as chemical fertilizer,organic fertilizer,straw returning,mixed application of chemical fertilizer and organic fertilizer,chemical fertilizer and straw returning did not significantly reduce soil fauna diversity.One possible reason is that the phenomenon of reciprocal growth and decline between different soil fauna groups in the face of external interference maintained the dynamic balance of soil fauna community structure to a certain extent.However,it seems that long-term agricultural cultivation inevitably has a tendency to reduce soil fauna diversity.Abandonment has a positive effect on Formicidae while recuperating farmland.The increase of Formicidae dominance of Omnivores may lead to the decrease of soil fauna diversity in abandoned land.Agricultural fertilization directly or indirectly provides energy for soil microorganisms,which is conducive to increasing soil microbial biomass.At the same time,large predatory soil faunas are relatively more likely to be affected by soil microbial communities,and the relationship with microorganisms is more complex.It can be seen that agricultural activities affect the farmland ecological environment by changing the physical and chemical properties of farmland and the soil fauna community and soil microbial community.This study found that the spatial heterogeneity of soil fauna communities is large,and the impact of agricultural activities on soil fauna communities may not be comparable to the differences in community structure caused by spatial heterogeneity.Detritivore and Omnivore soil fauna functional groups have a certain feedback effect on farmland yield,but the complex process is worthy of further study.