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Phosphorus (P), a crucial element for all life forms on Earth, is often insufficiently available in terrestrial ecosystems. The interaction and feedback between plants and soil microorganisms are crucial links integrating above‐ and below‐ground ecosystems. However, changes in soil P fractions in response to plant‐microbe interactions during vegetation succession remain poorly understood. This study investigated the trends and relationships between plant resorption, microbial properties, and soil P fractions in the transformation interface soil layer (TIS) and underlying topsoil layer (UTS) during grassland vegetation succession. The results point to a combination of soil properties, alongside microbial and plant factors driving soil P changes. However, the TIS and UTS layers differ, with phosphorus dynamics in the TIS layer primarily influenced by microorganisms. Microorganisms are co‐limited by C and P in both the TIS and UTS layers. Under microbial P‐limitation, microorganisms produce alkaline phosphatases (AP), while C deficiency stimulates the production of C‐acquiring enzymes, subtly regulating soil P dynamics through organic matter decomposition. Plant P resorption efficiency and microbial P‐limitation exhibit synergistic variations, reaching their lowest levels during the mixed Bothriochloa ischaemum and Stipa bungeana Trin (Bo.I + St.B) stage. This study emphasizes that P cycling is influenced by plant‐microbe‐soil interactions and feedback. Plants and soil microorganisms jointly regulate soil nutrient effectiveness and partitioning in the ecosystem. Plain Language Summary: Phosphorus (P) is an indispensable element found in all living organisms, essential for various biological functions like photosynthesis, energy transfer, and the synthesis of DNA and RNA. Focusing on vegetation restoration, we found that soil microorganisms faced limitations from both P and carbon (C). Notably, in the soil layer at the transformation interface, where plant litter was plentiful, microorganisms enjoyed improved access to P. This improvement was attributed to the plants in our study absorbing more nitrogen (N) than P, resulting in a higher concentration of P in their decomposing foliage. Furthermore, the production of alkaline phosphatase (AP) by microbes facilitates their access to additional P from the soil. From the viewpoint of P acquisition, an increase in microbial P‐limitation leads to a reduction in dissolved inorganic P, thereby enhancing the efficiency of plant P resorption. This process ultimately results in a net decrease in the total soil P content. Understanding the dynamics of P cycling in soil amid vegetation restoration is vital for the sustainable management of land. By ensuring that both plants and microorganisms have adequate access to P, we can foster successful and eco‐friendly vegetation restoration initiatives. Key Points: Microbial P limitation is more pronounced in the underlying topsoil layer compared to the transformation interface soil layerMicrobial factors such as extracellular enzymes are the main drivers of P variation within the transformation interface soil layerDuring the course of vegetation succession, microbial P‐limitation is found to enhance plant P resorption efficiency [ABSTRACT FROM AUTHOR]

Soil organic carbon (SOC) is the core component of terrestrial carbon (C) sink. Exploring the transformation and stabilization mechanism of SOC is key to understand the function of terrestrial C sink which copes with climate change. The traditional perspective is that plant residues are the initial source of SOC. The new concept of "soil microbial C pump" emphasizes that the synthesized products of soil microbial assimilation are important contributors to the stable SOC. This provides a new insight to the sequestration mechanism of SOC. Due to the complex and variable decomposition process of plant residues and the high heterogeneity of microbial residues, the transformation and stabilization mechanism of plant residues and microbial residues into SOC is still unclear. We reviewed research progress in plant and microbial residues, and introduced the characterization methods of quantification and transformation of plant residues and microbial residues, and also summarized the new findings on the transformation of plant and microbial residues into SOC. We further discussed the contribution and driving factors of microbial and plant-derived C to SOC. Finally, we prospected the future development direction and research focus in this field. This review would provide the scientific reference for the research of soil C sequestration in terrestrial ecosystem. [ABSTRACT FROM AUTHOR]