Soil Microbial Communities,Enzyme Activities And The Effect Factors Of Different Years After Starting Reclamation In Coal Waste Pile

Soil microbial and enzyme are important pivots for the material cycle and energy exchange in soil ecosystems,which are sensitive indicators for measuring soil quality and have important indications for the evolution of soil quality,and can also reflect changes in soil microenvironment earlier.Therefore,studying the response of soil microbial and enzyme to soil quality helps to understand the adaptation and evolution mechanisms of Soil microbial and enzyme to soil environmental changes,and promote the stability of soil ecosystem functions.In the process of reclamation and remediation of Coal waste pile in China,the method of planting vegetation after pushing over the cover soil is generally adopted.However,there are a series of quality problems in the reconstructed soil forming after pushing over the cover soil,such as poor soil structure,nutrients deficiency,water shortage heavy metal pollution and so on.Therefore,how to effectively evaluate the soil quality in reclaimed land is the key to carry out the vegetation restoration work in Coal waste pile.This study aims to find out the response of reconstructed soil microbial and enzyme to soil quality in Coal waste pile during different reclamation years by analyzing the relationship between the changes of soil microbial community structure,microbial biomass carbon,nitrogen and enzyme activities and soil properties,which is essential to guide the vegetation recovery in coal-bearing mountains of mining areas according to the actual situation in terms of time,at the same time,in which it also has important theoretical guidance value for conducting agricultural production reasonably.In this study,the orchards of 3a(R-3a),5a(R-5a)and 7a(R-7a)at Coal waste pile of Cao village in Shanxi Province were taken as examples to study the changes of 5 microbial communities(common bacteria,fungi,actinomycete,gram-positive bacteria andgram-negative bacteria),microbial biomass carbon,nitrogen,and 4 enzyme activities(catalase,alkaline phosphatase,dehydrogenase,urease)in 0-10 cm and 10-20 cm soil layers and analyze the effect of soil physicochemical properties on microorganisms and enzyme activity.The main findings are as follows:(1)It can be seen from the difference in soil physicochemical properties of three different reclamation-years sample plots that oil organic matter,total nutrients,available nutrients,water content,clay content,pH value,and cation exchange capacity,and organic carbon content in soil layers of 0-10 cm and 10-20 cm all enhanced significantly with the increase of the number of reclamation years,which was most obvious in R-7a plots but the available potassium content and conductivity showed a downward trend.At the same time,compared with those in the original orchard common orchard(CK),except that the soil nutrient content,water content,clay content,pH value,soil cation exchange capacity,and organic carbon are still significantly low in these three reclamation-year orchards.(2)It can be seen from the difference in total soil microbial PLFAs concentration and community PLFAs concentration of three different reclamation-years sample plots that the total concentration of soil microbial PLFAs enhanced with the increase of reclamation years and that the concentration of PLFAs in the soil microbial community had varying degrees of enhancement with the increase of reclamation years.In 0-10 cm soil layer,the concentration of PLFAs in Gram-negative bacteria and common bacteria increased most significantly,whereas the increase in the concentration of actinomycete PLFAs was only found in R-7a.In10-20 cm soil layer,the concentration of actinomycete PLFAs increased most obviously,while Gram-positive bacteria increased significantly only in R-7a plots.Compared with that in CK plot,the PLFAs concentrations of five microbial communities in the soil of three different reclamation-years sample plots were still low.The soil microbial community structure showed that Gram-positive bacteria and common bacteria accounted for the largest proportion,actinomycetes accounted for the smallest proportion,and fungi and Gram-negative bacteria changed in varying degrees.(3)It can be seen from the differences in soil microbial biomass carbon,nitrogen and enzyme activities of three different reclamation-years sample plots that the soil microbialbiomass carbon,nitrogen and enzyme activities showed different increase trend and that soil microbial biomass carbon and nitrogen enhanced overall with the increase of reclamation years.In 0-10 cm soil layer,the increase of microbial biomass carbon was more obvious.In10-20 cm soil layer,the increase of microbial biomass nitrogen was more obvious.Compared with those in CK plot,the soil microbial biomass carbon and nitrogen were much lower in three different reclamation-years sample plots.The enzyme activity also increased with the increase of reclamation years,and the activity of dehydrogenase and alkaline phosphatase increased most significantly in 0-10 cm and 10-20 cm soil layers.Compared with those in CK plot,the four enzyme activities were significantly lower in three different reclamation-years sample plots.(4)It can be seen from the relationship among the concentrations of PLFAs,microbial carbon,nitrogen,enzyme activity,and soil physical and chemical properties of soil microbial community in three different reclamation-years sample plots that the organic matter,total nitrogen,total phosphorus,total potassium,alkaline nitrogen,and effective Phosphorus,cohesive,organic carbon,water content,cation exchange capacity and pH have a great influence on the total concentration of PLFAs and PLFAs in the community;that organic matter,total nitrogen,total phosphorus,total potassium,available phosphorus and clay have a great impact on microbial biomass carbon and nitrogen;and that organic matter,total nitrogen,total phosphorus,total potassium,clay,organic carbon,and cation exchange capacity have a great effect on enzyme activity.