Dynamic features and mechanisms of soil aggregate stability related to soil carbon pools and microbially mediated functions under N input: Advances, issues, and future perspectives

In the context of food security and climate change mitigation, enhancing the stability of soil aggregate-mediated organic carbon (C) is crucial for long-term soil C sequestration in arid agroecosystems. Nitrogen (N) input, while essential for boosting crop productivity, profoundly influences soil aggregation, microbial activity, and the distribution of soil organic carbon (SOC) among functional pools. However, the mechanisms through which N regulates aggregate-associated SOC stabilization via microbial-mediated processes remain poorly understood. This review synthesizes recent advances on the effects of N input on soil aggregate dynamics, aggregate-associated SOC fractions, and microbial functional regulation in arid agricultural systems. We emphasize how N-driven shifts in microbial community composition, extracellular enzyme activities, functional genes, and glomalin-related processes influence aggregate formation and SOC protection. The novelty of this review lies in developing an integrated conceptual framework linking N input, soil aggregation, microbial functional responses, and aggregate-scale SOC stabilization. Our synthesis provides mechanistic insights to optimize N management strategies, thereby enhancing soil aggregate stability and maximizing long-term C sequestration, thereby promoting sustainable agriculture and climate change mitigation in arid regions.