Abstract:Soil organic phosphorus(P) is an important component of the soil P pool and its mineralization plays an important role in global P cycling. Understanding the mineralization of soil organic P is beneficial for the efficient utilization and management of P in terrestrial ecosystems. In recent years, the application of advanced techniques such as modern spectroscopy, chromatography, and mass spectrometry has provided crucial avenues for a more comprehensive characterization of the composition and structure of organic P. This review summarizes the applications of these technologies in quantifying changes in soil organic P content. Organic P, following mineralization, is converted into inorganic P(Pi), making it available for direct uptake and utilization by plants and microorganisms. Soil organic P mineralization is orchestrated by two primary pathways: enzymatic and mineral-mediated processes. Delving into the mechanisms of biological catalysis and abiological mineral-mediated catalysis is crucial for elucidating the control pathways of organic P. The mechanisms of soil organic P mineralization can be divided into biological mineralization driven by the oxidation of organic matter by microorganisms (phoA, phoD, and phoX) in response to energy demand, and biochemical mineralization driven by the release of Pi nutrients from plants in response to the demand for P nutrients mediated by phosphatases. Recent investigations have underscored the significance of minerals as an abiological mineralization pathway, shedding light on the mechanisms and actions of mineral-mediated catalysis. The surfaces of minerals (such as iron (hydro) oxides, manganese (hydro) oxides, and aluminum(hydro)oxides)provide an enzyme-like environment, facilitating the cleavage of phosphate ester (P-O-C) and terminal phosphoanhydride(P-O-P)bonds, resulting in the hydrolysis of organic P to Pi. In soil ecosystems, the biogenic elements carbon(C) and nitrogen(N) are intimately linked with soil organic P mineralization. From a nutrient factor perspective, elucidating the driving patterns of organic P mineralization can inform strategies to regulate soil P pools. Specifically, C effectively drives microbial mineralization of organic P, whereas N influences enzymatic metabolism, with the interplay between the two elements profoundly influencing the soil organic P mineralization process. The multiple forms of organic P present in soils are susceptible to influences from various external factors, which modulate phosphatase activity and alter organic P content, thereby further affecting the mineralization process. Various factors, including agricultural practices (such as fertilizer application, tillage practices, and biochar application), soil physical and chemical properties (such as pH, temperature, soil water content, and soil aeration status), microbial biomass, soil CO2 concentration, vegetation, and pollutants all impact soil organic P mineralization, resulting in corresponding environmental ecological effects. Therefore, regulating organic P mineralization is crucial for enhancing soil fertility and protecting the environment. Future strategies can focus on enhancing phosphatase activity, altering organic P composition, and increasing the abundance of phosphorus-solubilizing microorganisms to improve soil organic P mineralization. This review summarizes the advances in soil organic P mineralization research, synthesizing the soil processes, influencing factors, and control pathways, and highlighting the existing challenges and prospects.

Abstract:【Objective】 Phosphorus is an essential nutrient element that affects the growth, yield and quality of crops. Due to the application of a large amount of phosphate fertilizer and the lack of scientific management, the utilization rate of phosphate fertilizer is low and the environmental risk increases. Thus, it is important to know the effects of different amounts of exogenous phosphorus(P) addition on P bioavailability components in paddy soil under flooding conditions.【Method】 Three soil samples were collected from the new paddy field (NP, 2-3 years), medium-term paddy field (MP, 20-30 years) and old paddy field (OP, 400-500 years) in Sunjia small watershed of Yingtan, Jiangxi Province. Based on the flooding culture experiment (0-80 days) with different concentrations of exogenous P addition [0(CK), 125(P1), 250(P2), 500(P3), 625(P4), 750(P5) mg·kg-1], the test for simulating the bioactivation process of biologically based P(BBP method) was adopted. The dynamic changes in the increment(Δ) of soluble P(Ca-P), easily activated and released P(Ci-P), easily mineralizable acid phosphatase (En-P), and the potential inorganic P(HC-P) were analyzed, and the correlation between all P components and influencing factors were evaluated.【Result】 The results showed that under flooding conditions, exogenous P addition could significantly increase the available P(Bray-P) and BBP components such as Ca-P, En-P, Ci-P and HC-P in paddy soil, and the increment of P contents of each component increased significantly with an extension of P addition. The increment of BBP components was changed by the order:ΔCa-P < ΔEn-P < ΔCi-P < ΔHC-P. On day 15 of incubation, the ΔCa-P and ΔCi-P in the new paddy field reached a maximum value while on day 60, the ΔCa-P, ΔEn-P, ΔHC-P and ΔBray-P in the medium-term paddy field reached their maximum value. However, the P content of each component did not change significantly in the old paddy field. The ratio of ΔBray-P to ΔTP(ΔBray-P/ΔTP) in paddy soil after exogenous P addition showed the same trend as that of ΔBray-P, but there was no significant difference among different P additions. Path analysis showed that exogenous P addition had a significant direct positive effect on ΔBray-P in new and old paddy soil; ΔCi-P had a significant direct positive effect on ΔBray-P in new paddy field; ΔHC-P and ΔCa-P had a significant direct positive effect on ΔBray-P in medium-term paddy field, and ΔEn-P had a significant direct positive effect on ΔBray-P in old paddy field.【Conclusion】 Although exogenous P addition can significantly increase the components of the bioavailability of P in paddy soil, the emergence stage of the maximum increment bioavailability of P in paddy soil is different. Therefore, it is of great significance to timely and appropriately apply P fertilizers for the improvement of P fertility and the risk control of P loss in paddy fields.