Ten-year rice management enhances soil aggregate stability in salt-alkali soils: Role of Fe/Al oxides and organic carbon

Soil aggregates, the “structural skeleton” of the soil matrix, are fundamental to maintaining soil fertility, structural integrity, and ecosystem multifunctionality. Saline-alkali soils, which are widely distributed across arid and semi-arid regions worldwide, represent one of the most critical constraints to agricultural productivity. However, the mechanisms by which long-term rice management regulates aggregate stability in these soils remain poorly understood. To address this gap, we conducted a long-term field experiment in sodic saline-alkali soils of Baicheng, Jilin Province, northeastern China, including six treatments: rice management for 1, 2, 5, 8, and 10 years, and a non-cultivated control (CK). Soil samples (0–10 and 10–20 cm) were fractionated by aggregate size, and aggregate-associated SOC and Fe/Al oxides were quantified. Structural equation modeling (SEM) revealed that associations between long-term rice management and increased SOC and Fe/Al oxide contents, both of which were positively correlated with aggregate stability. Fe oxides were associated with the strongest positive correlations to stability, while soil salinity showed negative correlations. These findings suggest a hypothesized organic–inorganic synergistic cementation mechanism in which SOC (via encapsulation and biochemical bonding) and Fe/Al oxides (via mineral bridging) may jointly contribute to soil structure. This study deepens mechanistic understanding of soil physicochemical reconstruction in saline-alkali soils and provides a theoretical basis for sustainable saline soil rehabilitation under salinity stress. • Rice management in saline soils enriches soil organic carbon and Fe/Al oxides, boosting aggregates. • Fe oxides strongly correlate with resilience under saline stress in sodic soils. • Soil organic carbon and Fe/Al oxides synergies restructure aggregates in sodic rice soils for restoration.