Effect of different inoculation treatments on AM fungal communities and the sustainability of soil remediation in Daliuta coal mining subsidence area in northwest China

Artificial ecological engineering plays an important role in promoting the restoration of mining subsidence areas. To investigate the effects of field inoculation on soil remediation, field studies were conducted in Shendong Daliuta mining area in Yulin, northwest China. Amorpha fruticose plants were treated with under five different inoculations, Funneliformis mosseae (F. m), Rhizophagus intraradices (R. i), F. mosseae and R. intraradices (F. m + R. i), Pantoea sp. (CA), F. mosseae and Pantoea sp. (F. m + CA), as well as no inoculation (CK) as control. The diversity and structure of arbuscular mycorrhizal (AM) fungal communities, glomalin, and soil organic carbon (SOC), available phosphorus, available nitrogen, soil pH were investigated. Based on pyro-sequencing on small subunit ribosomal RNA genes (SSUs), 63 AM fungal operational taxonomic units (OTUs) were identified, which belonged to six genera and two families. F. m + CA inoculation exhibited the highest available phosphorus, the lowest N/P ratio, and higher the ratio between total glomalin-related soil protein (T-GRSP) fractions and soil organic carbon (SOC). Fungal community diversity indices, including Shannon-Wiener, Simpson, and pielou, in F. m inoculation were significantly lower than others, and the phylogenetic index in F. m + CA inoculation was the highest (P < 0.05). In addition, Permutational multivariate analysis of variance (PerMANOVA) and non-metric multidimensional scaling (NMDS) analyses showed that the distribution of AM fungal communities without F. m inoculation were not significantly different from CK. These results demonstrated that the diversities and structures of AM fungal communities were sensitive indicators for monitoring the environmental changes in subsidence area. Furthermore, structural equation model (SEM) showed that AM fungal diversity had direct effects on T-GSRP. In summary, field inoculation of Amorpha fruticose plants had a valid effect on soil remediation, and F. m + CA inoculation is the befitting combination for soil restoration in the experimental field.