Abstract: Soil microbial functional diversity is a key indicator of soil quality. Revealing the characteristics of soil microbial functional diversity and co-occurrence in reclaimed coal mining area is of great theoretical and practical importance for mining area reclamation and ecological reconstruction. This experiment was conducted in a reclaimed coal mining area of Shanxi Yuci Guanyao Yong’an Coal Industry Co., Ltd., with corn as the reclamation crop. Topsoil samples (0-20 cm) under eight treatments were collected after 1-year reclamation, namely, UL (untilled land), CK (reclamation without fertilization), PK (phosphorus and potassium fertilizer), NPK (chemical fertilizer), NPKB (chemical fertilizer combined with phosphate solubilizing bacterial fertilizer), M (manure), MNPK (manure combined with chemical fertilizer), MNPKB (combined application of manure, chemical fertilizer and phosphate solubilizing bacterial fertilizer). Biolog Ecoplates technique and multivariate analyses were used to determine carbon source utilizing capability, functional diversity, and co-occurrence characteristics of soil microbial community. The results showed that carbon source utilizing capability of soil microbial community as well as their diversity and richness were significantly increased by fertilized reclamation. The reclamation effects of MNPK and NPK were strongest among all the treatments. Results from principal component analysis (PCA) and biclustering heatmap analysis collectively showed that carbon source utilization profiles of the insufficient fertilization group (UL, CK and PK) differed from the sufficient fertilization group (NPK, NPKB, M, MNPK and MNPKB), and those profiles of treatments within each group were similar. Soil microbial functional activity under sufficient fertilization treatments was significantly higher than that of insufficient fertilization treatments. Network analysis revealed that carbon source utilization by soil microorganisms in sufficient fertilization treatments harbored a stronger co-occurrence characteristics and a more complex network than in insufficient fertilization treatments. Our results indicated that fertilized reclamation played a positive role in improving functional diversity of soil microorganisms in coal mining area even in relative short term (1 year), and that sufficient fertilization treatments with equilibrated NPK doses were helpful to restore the complex and stable community structure of soil microorganisms. The combined application of manure and chemical fertilizer as well as chemical fertilizer application alone had the best reclamation effects, which had practical potential in reclamation of coal mining area.

Key words: fertilization, Biolog, microbial functional diversity, co-occurrence network.