Soil phoD-harboring bacteria mediate the soil phosphorus conversion in response to nitrogen supply in Loess Plateau
摘要
The microbe phoD gene, which encodes alkaline phosphatase (ALP), is crucial for mineralizing organic phosphorus (Po) to bioavailable P. However, the effect of long-term nitrogen (N) addition on the phoD-harbouring microbial-mediated P cycle and its mechanisms are poorly understood.
MethodsWe performed an 8-year N application experiment on alfalfa in the Loess Plateau of China. Moreover, the soil P forms, ALP activity, and phoD-harbouring microbial community characters under different N addition rates (0, 50, 100, and 150 N ha−1 yr−1) were determined.
ResultsLong-term N addition significantly reduced soil phoD gene abundance, pH, AP, labile P, and ALP activity but significantly increased the percentages of NaOH-Po and residual P in total P. N application significantly changed the community composition of phoD microbes. Furthermore, we found that N application significantly reduced the dispersal limitation of stochastic processes, N50, N100, and N150 treatments decreased by 53.17%, 89.95%, and 85.82%, respectively, compared with the N0 treatment. Network analysis indicated that the microbial network in the high-N group showed higher links (354), average degree (7.08), closeness centrality (0.301), and neighborhood connectivity (7.644) compared to those of the low-N group microbial network (6.52, 0.292, and 7.057, respectively). According to structure equation models (SEM), the key factors determining ALP were N addition rates, phoD gene abundance, and soil pH.
ConclusionsOur study indicated that N application can promote microbial competition for P and reduce soil P availability via phoD-harbouring microorganisms in the alfalfa continuous cropping system.
Graphical Abstract