Effects of land reclamation on soil microbial community structure and function in the Huang-Huai plain mining area

The fertility of reclaimed soil in the Huang-Huai plain Mining Area is low, which is closely related to nutrient cycling. However, the microbiological mechanism of the effect of reclamation on soil nutrient cycling is still unclear. A total of 65 topsoil samples were collected from 4 reclamation areas and 1 control area in Dongtan mining area located in Zoucheng City, Shandong Province. High-throughput sequencing, PICRUSt2 and FUNGuild analysis tools were used to explore the effects of reclamation on soil microbial community structure and function, as well as unravel the environmental driving mechanism of microflora succession. The results showed that ① soil physical and chemical properties, and enzyme activities were significantly affected by reclamation (P<0.05). With increasing reclamation years, the ammonium nitrogen (AN) gradually increased, whereas nitrate nitrogen (NN), available phosphorus (AP), organic carbon (SOC), β-glucosidase (BG) and protease (PRO) activities decreased. The pH value and leucine aminopeptidase (LAP) activities presented the tendency of increasing first and then decreasing. ② Reclamation significantly affected the structure and composition of soil microbial community (P<0.05). The richness and evenness of soil microbial community increased with the increase of reclamation years. The dominant phyla of all treatments remained unchanged, but their relative abundances varied significantly. ③ Soil pH value, ammonium nitrogen and phosphatase dominated the variation of soil microbial community structure; ④ PICRUSt2 functional prediction showed that the gene function of bacterial community were similar, in which metabolism-related function was the most active one. The result of FUNGuild function prediction presented that the fungal community contained 2 monotrophic types, 3 mixed trophic types, 4 mono-functional groups and 14 mixed functional groups. This study enriches the knowledge of understanding the developmental microbiological mechanism of reclaimed soil, and provides a scientific basis for the management of coal mining subsidence in the Huang-Huai plains.