Long-term nitrogen addition changes phosphorus availability and reshapes phosphate-solubilizing bacterial community in purple soil of southwest China
Liuyan Zhou, Jianguo Jiang, Jun Xie, Yuanxue Chen, Huarong Guo, Wencai Dai, Rong Huang, Zifang Wang, Ming Gao
Abstract
Microorganisms play central roles in regulating soil phosphorus (P) cycling and availability retention. However, how long-term nitrogen (N) fertiliser application in intensively managed croplands affects soil microbial P metabolism remains unclear. In this study, we investigated the effects of different N applications on availability P, phosphatase activity, P functional genes, and microbes that participate in organic P mineralisation and inorganic P dissolution in a continuously managed (6 years) maize fields. The results showed that as the rates of N fertiliser increased, soil pH decreased, whereas AP content increased first before decreasing (N180 highest). A similar trend was found in the activities of alkaline and acid phosphatase. Furthermore, an increase in the N fertiliser application rate enhanced the abundance of phoX , pqqC , and gcd genes but decreased that of phoD and phoA genes. Structural equation modelling and random forest analysis revealed that total N and pH were the most important predictors of phoD - and pqqC -harbouring microbial composition, respectively. N180 and N270 treatments harboured higher modularity, nodes, links, and proportion of positive linkages in the phoD - and pqqC -harbouring microbial co-occurrence networks. Overall, different N applications reshaped the phoD - and pqqC -harbouring communities through direct or indirect effects, making it more flexible and efficient in improving the P-utilisation rate. These results have implications for sustainable agricultural management and will be helpful for deepening our understanding of soil microbial interaction and P activation mechanisms. • High N application decreases the available phosphorus and pH in soil. • P function gene and P-mobilisation microbes differ in sensitivity to added N. • Long-term N fertilisation reshapes pqqC - and phoD -harboring communities. • N addition induces an increase in microbial competition for P in the maize system.