Improving the quality of barren rocky soil by culturing sweetpotato, with special reference to plant-microbes-soil interactions

Biological process is an effective strategy to improve soil quality in agroecosystems. Sweetpotato has long been cultivated in barren rocky soil (BRS) to improve soil fertility and obtain considerably high yield. However, how sweetpotato cultivation affects soil quality is still unclear. We cultured sweetpotato in virgin BRS, and investigated its transcriptome, rhizospheric microbial community and soil properties. A high sweetpotato yield (22.69 t.ha−1) was obtained through upregulating the expression of genes associated with stress resistance, nitrogen/phosphorus/potassium (N/P/K) uptake, and root exudates transport. Meanwhile, the rhizospheric microbial diversity in BRS increased, and the rhizospheric microbial community structure became more similar to that of fertile soil, which might benefit from the increased root exudates. Notably, the relative abundances of N-fixing and P/K-solubilizing microbes increased, and the copy number of nifH increased 6.67 times. Moreover, the activities of acid, neutral, and alkaline phosphatases increased strongly from 0.63, 0.02, and 1.15–1.58, 0.31, and 2.11 mg phenol·g−1·d−1, respectively, and total carbon, dissolved organic carbon, available N/P content also increased, while bulk density and pH of BRS decreased, indicating the enhanced soil fertility. Our study found sweetpotato cultivation improved BRS quality through shaping microbial communities, which has important guiding significance for sustainable agriculture.