Construction of Compound Microbial Fertilizer Using High-Efficiency Phosphate-Solubilizing Bacterial combinations from Phyllostachys edulis Forest Soil and Its Growth-Promoting Mechanism

At present, the available phosphorus elements are scarce globally, mostly inorganic phosphorus that cannot be used by plants, and the subtropical region of China is the main production area for Moso bamboo(Phyllostachys edulis). The primary soils in this region are red soil and brick-red soil, in which a large amount of phosphorus cannot be directly absorbed and utilized by plants. This process relies on phosphorus-solubilizing microorganisms for conversion and utilization. Therefore, in order to realize the rapid conversion and efficient utilization of phosphorus elements, this study used the pot experiment to sample the end of the growth season(T₁) and the end of the rapid growth season(T₂) to verify the functional effect of the efficient phosphorus-soluble microbial strain combination in the growth process of bamboo seedlings. Additionally, specific carriers for the microbial strains were constructed to observe and analyze their effects on seedling growth and the phosphorus nutrient environment in the soil. The results showed that both freeze-dried and liquid microbial agents from the synthetic microbial community significantly promoted seedling growth and nutrient accumulation. Among them, the liquid microbial agent had the best growth-promoting effect during the T₁ period, with root biomass and total nitrogen content in the roots significantly increasing by 103% and 15.65%, respectively, compared to the control(CK). The freeze-dried microbial agent showed the best growth-promoting effect during the T₂ period, with soil total nitrogen and available phosphorus content increasing significantly by 16.11% and 11.05 times, respectively. The total biomass, as well as total nitrogen and total phosphorus content, increased significantly by 91.49%, 76.32%, and 122.58%, respectively, compared to CK. Further analysis through different carrier inoculation comparative experiments showed that a 1:1 volume mixture of peanut shells and sugarcane bagasse was suitable as the carrier for the synthetic microbial community.One year after the application of the phosphate-solubilizing solid biofertilizer constructed with this carrier, the soil available phosphorus significantly increased by 408%. At the T₁ stage, the root and aboveground biomass of Moso bamboo seedlings increased by 8.7% and 41.9%, respectively, compared to the control(CK). At the T₂ stage, the root and aboveground biomass of Moso bamboo seedlings increased by 32.3% and 746%, respectively, compared to CK. The preliminary results demonstrate that the highly efficient phosphate-solubilizing bacterial combination has a significant effect on the growth of Moso bamboo seedlings, and a specific biofertilizer was developed, providing a reliable solution to address phosphorus deficiency during the growth of Moso bamboo seedlings.