## 4 Discussion
### The Effects of Changing to Cash Crops on Basic Soil Properties in Moso Plantations
These microorganisms could promote the growth of Persimmon by improving the availability of phosphorus. As the core of the soilP transformation process, the expression of functional genes of the P cycle is the most direct quantitative indicator to evaluate the intensity of each component of the P cycle [31]. In this study, it was found that _phoU_, _pstS_ and other genes were the most abundant in Tea-oil soil. _phoU_ is a multifunctional regulator of microbial signal transduction and homeostasis and plays an important role in coordinating Pi transport and counter-ion regulation, controlling polyphosphate accumulation, and regulating secondary metabolite biosynthesis and DNA repair [32]. The transport genes _ugpA_, _ugpB_, _ugpE_, _gcd_ and _phoD_ had the highest abundance in Persimmon soil. Among them, _ugpA_, _ugpB_ and _ugpE_, as transport genes, play an active role in the process of soil phosphorus assimilation. _phoD_ gene is usually used as a biomarker of organic phosphate mineralization, and the mechanism of soil organic phosphate mineralization controlled by microorganisms carrying the _phoD_ gene through alkaline phosphatase has been confirmed [21; 33]. In addition, the content of dissolved inorganic phosphorus gene _gcd_ in the soil of Persimmon trees increased significantly, indicating that Persimmon trees may have a high demand for phosphorus and soil microorganisms respond to crop demand for phosphorus by increasing the expression of the _gcd_ gene, thereby promoting the absorption and utilization of phosphorus [34]. However, the relative abundances of _pqA_, _pqB_, _pstC_, and _pstS_ genes decreased after the change to Persimmon and Tea-oil species. The decrease in relative abundances of _pqS_ genes may reflect the adaptation of microbial communities to environmental changes [35]. Correlation Analysis Between Basic Soil Properties and Phosphorus-Functional Microorganisms After Moso Plantation Was Replanted with Cash Crops  
As a key component of the soil ecosystem, soil microorganisms play an important role in the cycling of soil nutrients and the decomposition of organic matter [36]. At the same time, soil moisture content and pH can significantly affect the composition and diversity of soil flora, and play an important role in the recycling of soil nutrients and the decomposition of organic matter [37]. Microbial biomass phosphorus is an important form of soil organic phosphorus, which covers the intracellular phosphorus content of all living microorganisms in soil [38]. We found that the P content of soil microbial biomass was closely related to the type of crops planted after the change to cash crops. Among them, the soil MBP content of Persimmon trees was the highest, which might be due to the developed root system of Persimmon trees, which was conducive to the attachment and growth of microorganisms, thus promoting the increase of microbial biomass. The content of soil P fractions is not only related to the basic properties of soil but also affected by the structure and function of soil microbial community [39]. The results showed that the abundances of _Bradyrhizobium_ and _Camellia_ were positively correlated with TP content in soil. _Bradyrhizobium_ is a kind of nitrogen-fixing bacteria, but previous studies have shown that an optimal phosphorus level is needed to effectively fix nitrogen and increase yield, making _Bradyrhizobium_ closely related to the phosphorus content in soil [40]. In addition, the abundance of _Reynatella_, _Steroidter_ and _Pseudolabrys_ was significantly positively correlated with soil pH, SOM, AP, EC, TN and MBP indices, while _Amyclatoppsis_ was significantly negatively correlated with these soil indices, with the highest relative abundance in the control soil and the lowest abundance in Persimmon soil. _Amyclatoppsis_ is widely distributed in soil [41] and can activate insoluble phosphorus in soil by secreting phosphatase, thereby promoting the recycling and reuse of nutrients.