Effect Of Organic Management And Hedgerows On Biota Diversity In Farmland

Although intensive agricultural production has brought higher food production,it may also lead to soil pollution,loss of ecological diversity and other problem.In order to mitigate the negative effects and enhance sustainable production capacity,some eco-friendly production methods with the elements of recycling and reduction have been widely used in agricultural production,such as applying biogas fertilizer,adopting biological control measures,and preserving the semi-natural habitat around farmland.The evolution of farmland soil biomes and organic matter and the complex multidimensional interactions between them are cutting-edge areas and challenges in agroecology,as well as bottelnecks of foundalmental research in sustainable agriculture.However,systematic knowledge has not yet been developed on the effects of different agricultural management on farmland soil organic matter and biodiversity as well as their underlying mechanisms.In this project,we studied the field farmland with long-term(more than 10 years)organic cultivation(EM)and conventional cultivation(CM),as well organic farmland with semi-natural habitats such as plant hedgerows(EMH).We analyzed the effects of different agricultural management on soil dissolved organic matter(DOM),soil microbial community,nematode community and spider community in a real farming environment.The main findings of the study are as follows.(1)Organic management,especially hedgerows,can effectively increase soil organic matter content and humification capacity.Compared to CM,soil organic matter content in EM and EMH were elevated by 20%.The results of 3D excitation-emission matrix fluorescence spectroscopy showed that soil DOM content in EM and EMH were elevated by 38% and 74% respectively,while the humification index increased and the biological index decreased,indicating that organic management measures promoted soil humification and soil organic matter stability was improved.(2)Both organic management and hedgerows had significant effects on soil microbial community diversity and increase the abundance of populations and functions associated with nutrient cycling.Compared to CM,the homogeneity of bacterial communities in EM and EMH soils was elevated,and hedgerows had a significant effect on this elevation.There were significant differences in the composition of dominant taxa such as Actinobacteria,Proteobacteria,Chloroflexi and Ascomycota under different treatments,and organic management had a significant effect on eukaryotic microbial communities,while hedgerows had a significant effect on bacterial communities.Functional prediction analysis showed that the EM and EMH soils exhibited a higher abundance of chemoheterotrophic and aerobic heterotrophic functions,indicating that organic managemen t and hedgerows may contribute to improved nutrient utilisation and crop growth.(3)Organic management and hedgerows were able to increase soil nematode community diversity and alter nematode community composition.Compared to CM,nematode taxa in EM and EMH showed a significant decrease of herbivores nematode density and an increase of bacterivorous and omnivorous/predatory nematode densities.Ecological index analysis showed higher diversity,structural index,enrichment index and nematode channel ratio under EM and EMH treatments,indicating that the soil was relatively healthy and the microfood web was dependent on bacterial decomposition pathways and less disturbed.(4)The spider community structure of the farmland showed high heterogeneity under different management measures.Compared to CM,the Shannon index of EM and EMH increased by 22% and37%,and the evenness index by 27% and 33%,respectively,indicating that adopting organic measures and preserving semi-natural habitats such as hedgerows were important measures to maintain spider species diversity in farmland.(5)Both soil microbial and nematode community structure showed significant correlations with soil DOM content and components.Procrustes analysis showed that nematode communities had similar distribution patterns to both microbial and spider communities,which may suggest that management measures brought similar driving forces to different taxa of the soil food web,and the driving force may be related to soil DOM.In conclusion,organic management and retention of hedgerows can increase soil organic matter content and humification capacity,and elevate the diversity of soil microbial communities as well as soil faunal communities,which are effective measures to enhance soil fertility and biodiversity in farmland.