Effective climate change mitigation through land-based strategies requires maximizing soil carbon (C) sequestration across land uses and management practices. Yet, land-use and management impacts on soil C and nitrogen (N) fractions and their distribution in soil profiles in water-limited environments remain elusive. We evaluated various labile and stable pools of soil C and N at 0-15, 15-30, and 30-60 cm depths under four long-term land uses - continuous alfalfa and tall fescue systems, a conventionally managed annual cropping system, and cottonwood orchard - to understand land use-driven changes in soil C fractions in different depths, and total profile C sequestration. Results showed that C and N fractions were allocated differently across depth layers, suggesting divergent mechanisms of C sequestration at different depths. Perennial systems increased labile and stable C pools, specifically at 0-15 cm, thereby supporting biologically mediated soil organic C (SOC) sequestration. The annual cropping system accumulated greater mineral-associated organic C (MAOC) and inorganic C at 30-60 cm, mediated by the physicochemical pathway of C formation and stabilization. At 0-60 cm, soil inorganic N and potentially mineralizable N (PMN) were 2.4-7.3 and 3.8-8.4 times higher, respectively, under annual crops than other land uses. The profile distribution of labile N and C fractions relative to MAOC played a crucial role in SOC sequestration in various depths. The potential of arid soils to sequester C varied with vegetation type and land use. Management practices should focus on optimizing the distribution of labile C and N throughout the profile to promote microbial activity and enhance soil C sequestration. (c) 2025 International Research and Training Center on Erosion and Sedimentation and China Water and Power Press. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).