Spatial Distribution Characteristics And Driving Factors Of Soil Microbial Communities In Long-term Maize Continuous Cropping Fields Of Jilin Province

Jilin Province is located at one of the "Three Golden Corn Belts" in the world,and the per unit yield of corn and the rate of commercial grain have been in the forefront for many years in China.Although continuous cropping of corn for many years effectively increased grain yield,it also led to the decline of cultivated land fertility,such as soil consolidation,low nutrient utilization efficiency,change of soil microbial community,inhibition of maize seedling growth and so on.Soil microorganisms play an important role in the formation of soil fertility,nutrient absorption,growth promotion and biological stress resistance of plants,and are an important part of soil.However,the biogeographic distribution of soil microorganisms in maize continuous cropping is still unclear.In this study,25 soil samples were collected within 659 km,and high-throughput sequencing technique was used to explore the diversity,community composition and biogeographic distribution of bacteria and fungi in maize continuous cropping soil of Jilin Province.The results are as follows:1.Soil p H ranges from 5.14 to 8.33.The contents of soil organic matter,total nitrogen,total phosphorus and available phosphorus are generally high,and there is a high correlation among chemical properties.The soil nutrients change in latitude gradient,and soil nutrients decrease with the increase of latitude.The soil nutrients are closely related to precipitation,indicating that precipitation may be an important factor affecting soil nutrient mineralization and accumulation.2.The diversity of bacterial community in low latitude area is relatively high,which indicates that there may be a latitude gradient of bacterial community diversity in maize continuous cropping soil.The dominant phyla in soil(relative abundance > 5%)were Proteobacteria(52.61%),Acidobacteria(13.62%),Actinobacteria(10.43%)and Gemmatimonadetes(6.82%).Non-metric multidimensional analysis(NMDS)and redundancy analysis(RDA)showed that the composition of soil bacterial community was mainly affected by soil p H and total phosphorus content,and the effect of soil p H was greater than that of total phosphorus.The similarity of bacterial community composition showed a significant " Distancedecay" model(P < 0.001).The variation partitioning analysis(VPA)shows that the variation of soil microbial community composition can explain 55.9%,the contribution rate of geographical distance is 4.1%,and the contribution rate of environmental factors is 51.4%,in which soil factors are greater than climate factors.Our results show that in the process of shaping the soil bacterial community of maize continuous cropping in Jilin Province,contemporary environmental factors(such as soil p H,total phosphorus)are more important than historical factors(geographical distance).3.Similar to the results of the study on bacterial community in maize continuous cropping soil in Jilin Province,the diversity of fungal community increased with the decrease of latitude,indicating that there may also be a latitude gradient of fungal community diversity.The dominant fungal phyla in soil(relative abundance > 5%)were Ascomycota(64.76%),Basidiomycota(15.50%)and Mortierellomycota(9.14%).Non-metric multidimensional analysis(NMDS)and canonical correspondence analysis(CCA)showed that the average annual precipitation had the greatest effect on the composition of fungal community,followed by soil p H.The similarity of fungal community composition showed a "distance-decay" trend similar to that of bacterial community(P < 0.001).The variation partitioning analysis(VPA)showed that the contribution rate of geographical distance to fungal community variation was 5.7%,and the contribution rates of soil and climate factors were 26.2% and 13.7%,respectively.Our results show that contemporary factors such as soil p H and annual average precipitation are more important than historical factors such as geographical distance in shaping soil fungal communities in maize continuous cropping in Jilin Province.To sum up,this study revealed the important ecological factors affecting the diversity,composition and niche differentiation of bacterial and fungal communities by investigating the biogeographic distribution of bacteria and fungi in maize continuous cropping soil in Jilin Province.The results provide a new insight for the construction of soil microbial community in maize continuous cropping in Jilin Province and lay a theoretical foundation for the subsequent maintenance or restoration of normal soil ecological function.