Characteristics of soil phosphorus fractions and microbial communities in different Camellia oleifera intercropping modes

Phosphorus is one of the important limiting nutrients for plant growth in the red soils of southern China. Understanding how the intercropping affect soil phosphorus fraction and availability is crucial for maintaining P demand in Camellia oleifera agroforestry system. Here, we investigate the effect of intercropping on soil phosphorus fraction, availability and phoD-harboring bacteria community under three plantation types, namely C. oleifera monoculture (CK), C. oleifera intercropping with Capsicum annuum L (CC), and C. oleifera intercropping with peanut (CP). Compared to CK, CP significantly increases the NaHCO3-Po content but decreases the NaOH-Po content; additionally, the EAP content significantly increases while the MAP content significantly decreases. The NaOH-Pi content of CC is significantly higher than CK, while the Residual-P content is significantly lower, accompanied by a notable decrease in NAP content.Intercropping exerts an influence on soil phosphorus effectiveness by modulating the phoD-harboring bacterial community. Overall, Camellia intercropping can improve soil phosphorus availability to a certain extent, but the effects of intercropping with different crops on phosphorus availability vary. In summary, the practice of intercropping with peanuts proves more advantageous in enhancing phosphorus availability, rendering it a planting strategy meriting greater promotion within agricultural production.