Linking soil phosphorus fractions to associated microbial functional profiles under crop rotation on the Loess Plateau of China

Crop rotation plays an essential role in maintaining soil fertility and is meaningful to soil health and sustainable agricultural management. However, the impact of crop rotational regimes on the soil phosphorus (P) fractions and associated phosphorus cycling (P-cycling) profiles driven by microbial communities are not well elucidated. Hence, we used metagenomics to comprehensively investigate the variations in soil microbial P-cycling functional genes and representative processes, as well their regulations for soil P fractions among distinct crop rotational regimes and complexity. Most soil properties, particularly P fractions, were significantly greater in corn rotations than other crop rotations. The composition of P-cycling functional genes and microbial communities was also distinctly clustered in accordance with crop rotational regimes to varying degrees. The potential of representative P-cycling processes was all significantly higher in the complex rotation. Notably, the key functional genes including phoD, ppx, pstB, ugpA were differently screened from each P-cycling process and assembled toward the middle of their networks. Furthermore, soil potential carbon mineralization as a dominant property regulated several P-cycling processes and was intimately associated with the key P-cycling functional genes. Crop rotational complexity and the P-uptake and transport process had profoundly total effects on soil P fractions. Overall, this study provides a deep insight into soil microbial P-cycling functional profiles for developing sustainable soil P management practices at crop rotational agroecosystems.