| The northeast Mollisol area is the most important commercial grain production base in China because of its high organic matter content and rich nutrition.In recent years,the extensive use of chemical fertilizers,pesticides and plastic film has led to a large number of petrochemical products being imported and accumulated in the soil,which eventually led to a series of organic pollution and heavy metal pollution problems in the farmland ecosystem of northeast Molisol area.Microbes are the most active and important biological components of soil ecosystems,playing a key role in driving biogeochemical processes,controlling pathogens,and ultimately enabling ecosystem's function and serve.Soil microorganisms were sensitive to environmental stress,and changeed in their composition and diversity can reflect changes in soil quality in a timely manner.They were key indicators for assessing soil changes caused by natural or man-made disturbances.Soil microbes showed a clear spatial distribution pattern on a global scale,and their community structure is mainly influenced by contemporary environmental factors and historical evolutionary factors.In order to better understand the composition,diversity and driving factors of bacterial community in Mollisols,we selected 9 facility agricultural lands with similar routine management in the northeast Mollisols area for sampling,and described them on a large spatial scale based on Illumina Miseq sequencing technology.The main results of this study are as follows:(1)Soil organic matter(SOM),p H,cation exchange capacity(CEC),total phosphorus(TP),available phosphorus(AP)and total nitrogen(TN),and other physical and chemical properties of the change of season did not present certain regularity,but the physical and chemical properties associated with latitude,in addition to soil total nitrogen,and latitude are positively related to other properties.(2)The bacterial community diversity of agricultural facility black soil was different in different seasons,which was manifested as: summer>autumn>winter>spring.The principal component analysis based on OUT(operational taxonomic units)level found that the bacterial community distribution showed obvious seasonal differences.The bacterial communities were similar in summer and autumn,and similar in spring and winter,but the bacterial communities were significantly different in summer,autumn and spring and winter.In different parts of the spring big difference on the alpha diversity of soil bacteria,and alpha diversity index and correlation analysis found that the physical and chemical properties and geographic latitude,OTU number and soiltotal phosphorus(r=0.783,P=0.013)were significantly correlation,Shannon index and soil p H(r=0.700,P=0.036),and organic matter(r =0.683,P=0.042)were significantly correlation,but the alpha diversity index have no significant correlation with latitude.(3)Illumina Miseq sequencing results showed that 37 phyla,89 classes and 538 genera were detected in black soil of agricultural facilities.The dominant phyla and dominant phyla were basically the same in different seasons and the abundance differences were not significant.The abundance of dominant bacteria was the same in summer and autumn,and the same in spring and winter.The dominant phyla and dominant fungi of soil bacterial communities in different regions are basically the same,but their abundance varies greatly.(4)The dominant bacteria in the soil and the physicochemical properties of the soil and the principal component analysis of PAEs(Phthalic Acid Esters)showed that soil properties(i.e.,p H,organic matter,bulk density and nitrogen,potassium and phosphorus content)and PAEs levels,rather than geographical latitude,explained the major variations in the bacterial community structure.These factors accounted for 73.04% of total bacterial community variation.Among them,PAEs,as a typical soil pollutant,is the main factor driving the composition of bacterial community in the black soil of facility agriculture. |
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