Response characteristics of soil microorganisms and enzyme activities to different soil remodeling modes in open-pit mine

The development of coal resources meets the needs of social and economic development, but it also brings about the problem of surface soil scarcity caused by surface soil excavation. The use of mining solid waste to reconstruct the soil is an important measure for land reclamation in open-pit grassland mining area to make it available for vegetation restoration. Compared with the undamaged soil, the community structure characteristics of soil microorganisms in the reclaimed land have changed, resulting in affected land quality after reclamation. The structural characteristics and change rules of soil bacterial community can reflect the diversity and ecological function of soil microbial community in the mining area, and reflect the level and quality of soil reclamation. At present, researches mainly focus on the physical and chemical properties of reclaimed soil, and the effects of soil remodeling on microbial and enzyme activities are relatively lacking. In this study, soil and vegetation samples were collected and one-way ANOVA was used to analyze soil microorganisms and enzyme activities of each reclaimed field under different soil reconstruction methods in Shengli Coal Mine, Xilinhot City, Inner Mongolia Autonomous Region. The results showed that: Among the reclaimed fields under the three reconstruction methods, the number of soil microorganisms under different reconstruction methods is bacteria which accounts for more than 99.00%, actinomycetes account for about 0.70%, and fungi accounts for the least, about 0.10%. The differences in the number of microorganisms among the fields under different reconstruction methods are as follows: the number of bacteria and fungi in the mixed field of rock and soil, coal ganges and fly ash (SGA) are higher than those of the other two reconstruction methods. The number of actinomycetes in (S) is higher than that of the other two reconstituted fields. Geotechnical field (S) mixed with geotechnical gangue field (SG) of the same type of enzyme concentration difference is small, but the content of invertase in the field mixed with the mixed field of geotechnical coal gangue and fly ash (SGA) is different from that of the former two. The difference of reclamation methods is small, the content of urease is 10.00% lower than that of the first two reclamation methods, and the content of phosphatase is 10.00% higher than that of the first two reclamation methods. Under the same structure pattern, the microbial and enzyme activities in the field generally decreased with the increase of vegetation level. In general, when the vegetation level is different in the fields under the three reconstruction methods, there are certain differences in the number of microorganisms and enzyme activities. This may be due to the good water retention performance of the gangue located 0-20 cm in the surface layer. The strong water absorption of fly ash provide a suitable living environment for soil microorganisms. It may be an ideal soil reconstruction model to use solid waste to solve the problem of scarce topsoil for land reclamation in the eastern grassland mining area. © 2022 by the Author(s).