Effects of Feldspathic Sandstone Addition on Microbial Biomass, Soil Enzyme Activity, and Bacterial Community Structure of Sandy Soil

Desertification is a serious environmental problem worldwide. In this study, a long-term field experiment was conducted to investigate the effects of feldspathic sandstone on remediation of sandy soil. The results indicated that feldspathic sandstone addition increased the soil moisture, available N, P, K content, organic matter content, and cation exchange capacity of the sandy soil. The microbial biomass carbon increased 130.12%, 135.45%, and 120.34% in the compound soil with the feldspathic sandstone and sand mass ratio of 1:1, 1:2, 1:5, respectively, and the microbial biomass nitrogen increased 102.38%, 107.45%, and 81.69%, respectively. Meanwhile, soil urease, catalase and surface activity were significantly enhanced (p < 0.05). Illumina sequencing revealed the differences of bacterial community structure between compound soil and sandy soil. The Acidobacteriota was more abundant in sandy soil while Proteobacteria and Firmicutes were more abundant in compound soil. Proteobacteria and Firmicutes are involved in nutrient cycling and plant residues degradation, respectively. Their enrichment is beneficial for soil quality improvement. Redundancy analysis indicated that available N, K, organic matter and soil moisture content are key factors that involved in the assembly of bacterial community. Overall, adding feldspathic sandstone into sandy soil improved soil physiochemical properties, enhanced soil microbial activity and optimized the bacterial community, which would ultimately improve the quality and ecological function of the sandy soil.