Distribution of Soil Organic Carbon in Root Zones at Different Distances from the Central Axis of Maize Rhizomes and Its Response to the Regulation of Organic Material

Abstract [Aims] In view of the current problems of ambiguous boundaries and difficult operation of rhizosphere and non-rhizosphere soils (such as the process of shaking roots is complex and inaccurate), [Methods] this study proposed a method for dividing root zone soil based on the different distances of the centerline of maize rhizomes: root-adjacent soil (R 0 , 0–5 mm), near-root soil (R 5 , 5–50 mm), secondary near-root soil (R 50 , 50–150 mm), and distant Root Soil (R 150 , 150–325 mm), to explore the spatial distribution characteristics of soil organic carbon (SOC) in the root zone. It clarifies the horizontal distribution characteristics of root parameters (root length density, root average diameter density, root surface area density, and root volume density) and SOC at different distances, and investigates the correlation between root parameters and SOC with and without organic matter application. [Results] The results indicate that corn root parameters decrease with increasing horizontal distance. The distribution trend of SOC is similar to that of root distribution, with the difference that in the R 5 zone, the SOC content shows a significant "carbon (C) trough" with a decrease of 2.1%—10.0%. Root parameters showed a significant correlation with SOC before organic matter application, but this correlation weakened after fertilization. [Conclusion] This indicates that SOC sequestration in the root zone shifted from a “root-dominated” single-regulation model to an indirect model involving multiple interactions. This study provides new insights into the functional differentiation of root systems and the mechanisms underlying soil C sequestration in root zones, offering guidance for precision field management.