A global meta-analysis of rhizosphere impacts on soil and microbial stoichiometry in agroecosvstems

Abstract. The stoichiometry of the rhizosphere, particularly concerning carbon (C), nitrogen (N), and phosphorus (P), reflects the balance between nutrient mineralization and retention during organic matter decomposition. However, the magnitude and underlying mechanisms of rhizospheric influences on soil and microbial stoichiometry remain insufficiently quantified at the global scale across diverse agroecosystems. This study synthesizes data from 113 peer-reviewed sources, encompassing 882 individual observations. The results reveal that the rhizosphere significantly increases soil C:N, C:P, and N:P ratios, while concurrently decreasing microbial C:N, C:P, and N:P ratios relative to bulk soil conditions. Notably, the rhizospheric effects on soil C:N ratios is amplified in humid regions and diminished in arid environments. In contrast the influence on microbial C:N exhibits a positive correlation with increasing soil organic C and ammonium N concentrations. Moreover, sensitive crops such as maize and vegetables enhance the rhizospheric soil C:N ratio by 5.68 % and 8.91 % respectively, while reducing the microbial C:N ratio by 11.00 % and 19.44 %. Soil organic C and ammonium N emerge as key determinants of rhizospheric soil and microbial C:N ratios, contributing 37.9 % and 30.3 % to their varations, respectively. The study establishes a coupled relationship between rhizospheric soil and microbial stoichiometry. These findings offer critical insights into rhizospheric nutrient cycling, which are essentials for improving soil health and optimizing nutrient use efficiency through targeted management practices.