Organic amendments promote soil phosphorus related functional genes and microbial phosphorus cycling

Phosphorus (P) mobilization by soil microorganisms plays a crucial role in determining the fertility and productivity of terrestrial ecosystems, yet the synthesis of impact of fertilization strategies on this process remains poorly understood. To fill this knowledge gap, we conducted a meta-analysis of 1082 observations from 85 independent fertilization experiments to evaluate how the abundance and diversity of P related functional genes (phoD, phoC and pqqC) and microbial P cycling responded to fertilizer addition. Overall, we found that amendment with organic matter (OM) alone or with inorganic fertilizer (OM + IF) enhanced soil microbial P (MBP), soil phosphatase activity, and the phoD gene abundance. Conversely, addition of nitrogen (N) fertilizer increased pqqC gene abundance but decreased MBP and phoD gene abundance. P fertilizer increased MBP and the diversity of the phoD gene, while combined NP addition (with or without potassium, K) increased acid phosphatase activity, MBP, pqqC gene abundance and the diversity of the phoC gene. Specifically, the effects of fertilizer addition on rhizosphere properties varied with fertilizer type: OM increased rhizosphere phosphatase activity and phoD gene abundance, whereas P and NP(K) fertilizers decreased them. Furthermore, as annual temperature and precipitation increased, the influence of OM on soil phosphatase activity and phoD gene abundance increased, while the effect of P addition on the Chao1 index of phoD reduced. As experimental duration lengthens, the effect of OM on phoD gene abundance was strengthened, while the effect of N addition was suppressed. Across all fertilizer studies, structural equation models suggested that soil phosphatase activity was closely correlated with soil organic carbon (SOC), soil pH, and phoD or phoC gene abundance. This comprehensive analysis highlights the benefits of OM and OM + IF over synthetic fertilizer for soil microbial P cycling and associated functional genes, providing profound insights into P mobilization and use efficiency in terrestrial ecosystems.