Soil microorganisms play a crucial role in the phosphorus (P) cycle, influencing P availability to plants. P deficiency is common in weathered and tropical soils, and the efficiency of P use by plants is often poor despite the presence of significant total P. The finite nature of high-quality rock phosphate sources underscores the need for more efficient P use in agriculture. Microorganisms can enhance P availability through various mechanisms, including solubilization of precipitated forms of calcium phosphates, alteration of sorption equilibria, and induction of metabolic processes that solubilize and mineralize P from sparingly available forms. These mechanisms are important for improving P nutrition in plants, especially in high-input systems and in developing countries where access to fertilizers is limited. Microbial activity in the rhizosphere is complex, with interactions between microorganisms and plants being difficult to manage. However, certain microorganisms, such as rhizobia and mycorrhizal fungi, have been successfully used to enhance P availability. Microbial biomass P is a dynamic pool, with significant turnover rates and potential for P release. The rhizosphere is characterized by increased microbial activity due to root exudates, leading to P depletion and mobilization. Phosphatase enzymes, both plant and microbial, are crucial for mineralizing organic P, and their activity is often enhanced under P deficiency. Microorganisms can solubilize inorganic P through acidification of growth media and release of organic anions. Inoculation of plants with P-solubilizing microorganisms can improve growth and P nutrition, especially under controlled conditions. However, field performance is inconsistent, often attributed to factors such as microorganism persistence and understanding of mechanisms. The role of microorganisms in P mobilization is complex, with interactions between plants and microorganisms influencing P availability. Future research should focus on understanding microbial interactions, developing effective inoculants, and improving the predictability of P mobilization in soils. Molecular tools and metagenomic approaches are providing new insights into microbial community structure and function, offering opportunities for better management of P availability in agricultural systems. Overall, soil microorganisms are integral to P cycling and have the potential to enhance P use efficiency in sustainable agriculture.Soil microorganisms play a crucial role in the phosphorus (P) cycle, influencing P availability to plants. P deficiency is common in weathered and tropical soils, and the efficiency of P use by plants is often poor despite the presence of significant total P. The finite nature of high-quality rock phosphate sources underscores the need for more efficient P use in agriculture. Microorganisms can enhance P availability through various mechanisms, including solubilization of precipitated forms of calcium phosphates, alteration of sorption equilibria, and induction of metabolic processes that solubilize and mineralize P from sparingly available forms. These mechanisms are important for improving P nutrition in plants, especially in high-input systems and in developing countries where access to fertilizers is limited. Microbial activity in the rhizosphere is complex, with interactions between microorganisms and plants being difficult to manage. However, certain microorganisms, such as rhizobia and mycorrhizal fungi, have been successfully used to enhance P availability. Microbial biomass P is a dynamic pool, with significant turnover rates and potential for P release. The rhizosphere is characterized by increased microbial activity due to root exudates, leading to P depletion and mobilization. Phosphatase enzymes, both plant and microbial, are crucial for mineralizing organic P, and their activity is often enhanced under P deficiency. Microorganisms can solubilize inorganic P through acidification of growth media and release of organic anions. Inoculation of plants with P-solubilizing microorganisms can improve growth and P nutrition, especially under controlled conditions. However, field performance is inconsistent, often attributed to factors such as microorganism persistence and understanding of mechanisms. The role of microorganisms in P mobilization is complex, with interactions between plants and microorganisms influencing P availability. Future research should focus on understanding microbial interactions, developing effective inoculants, and improving the predictability of P mobilization in soils. Molecular tools and metagenomic approaches are providing new insights into microbial community structure and function, offering opportunities for better management of P availability in agricultural systems. Overall, soil microorganisms are integral to P cycling and have the potential to enhance P use efficiency in sustainable agriculture.