Enhancing Soil Phosphorus and Potassium Availability in Tea Plantation: The Role of Biochar, PGPR, and phosphorus- and potassium-bearing Minerals

The utilization of phosphorus- and potassium-bearing minerals, plant growth-promoting rhizobacteria (PGPR), and biochar presents a promising strategy for enhancing soil phosphorus and potassium availability. However, the synergistic effects and underlying mechanisms that facilitate this optimization are yet to be fully elucidated. This study aims to use the combined benefits of phosphorus- and potassium-bearing minerals, PGPR, and biochar to improve the availability of phosphorus and potassium in soil for tea plants, and at the same time, uncover the mechanisms responsible for this improvement. The results showed that combined application of phosphorus- and potassium-bearing minerals, PGPR, and biochar had stronger positive impacts on tea yield, phosphate and potassium content in tea leaves, and the availability of phosphorus and potassium in soil, compared to using them individually or in pairs. Employing Random Forest and Partial Least Squares Structural Equation Modeling, we revealed that Chloroflexi bacteria harboring pqqc functional genes are pivotal in augmenting soil phosphorus availability. Furthermore, beta-Glucosidase, NaHCO3 extracted phosphorus, available potassium, and potassium in tea leaves also had a significant influence on phosphorus availability. For potassium availability, the critical factors included phosphate-solubilizing bacteria counts, catalase activity, available phosphorus, cation exchange capacity, organic matter, and potassium content in tea leaves. In summary, our research conclusively shows that the integration of phosphorus- and potassium-bearing minerals, PGPR, and biochar represents an effective approach to enhancing phosphorus and potassium accessibility in soil, thereby offering a viable alternative to conventional phosphorus and potassium fertilizers in tea cultivation.