Aggregate stability and organic carbon stock under different land uses integrally regulated by binding agents and chemical properties in saline‐sodic soils

Abstract

Aggregate stability and soil organic carbon (SOC) are critical for maintaining soil structure and preserving soil productivity. Land use substantially affects the process of soil aggregate stabilization and SOC sequestration, yet the detailed mechanisms have not been well studied in degraded soil ecosystems (e.g., saline-sodic soils).Therefore, to interpret the effects of land-use changes on soil aggregate stability and SOC stocks in saline-sodic soils, soils were sampled from four major land-use areas (degraded meadow, artificial forest, sorghum field, and paddy field) in Northeast China. The results showed that artificial forest soils exhibited the greatest proportion of water-stable aggregate (>250 μm) in 0-10 and 10-20 cm layers than sorghum and paddy field, which was mainly due to the absence of tillage disturbance. The highest SOC stock (59.79 Mg ha À1 ) was observed in paddy soils, indicating its greater SOC sequestration potential than those of other land uses. The variance partition analysis (VPA) revealed that soil parameters resulted in 85.1% variation regarding soil aggregate stability, in which the chemical characteristics (i.e., pH, EC, exchangeable Na + , and exchangeable sodium percentage) contributed 23.1%, binding agents (SOC, exchangeable Ca 2+ , and poorly crystalline Fe/Al oxides) contributed 20.6%, and their interactions contributed 39.5%. Binding agents directly participated in soil aggregation processes by forming clay-polyvalent metal complexes, while the chemical characteristics indirectly promoted soil aggregation via increasing various binding agents.Understanding the interactions between binding agents and clay are important for promoting soil aggregate stabilization in saline-sodic soil.

The formation of small macro‐aggregates induces soil organic carbon stocks in the restoration process used on cut slopes in alpine regions of China

“…The oxalate-extractable Fe/Al oxides can improve soil aggregate stability by forming complexes with clay under saline-sodic soil (Feng et al, 2021). The relatively high clay content in our study seems to support this view.…”

“…This may the cementation of inorganic components (crystalline Fe/Al oxides) plays a more vital role in soil aggregate stability than soil organic matter (Torres‐Sallan et al, 2018). The oxalate‐extractable Fe/Al oxides can improve soil aggregate stability by forming complexes with clay under saline‐sodic soil (Feng et al, 2021). The relatively high clay content in our study seems to support this view.…”

“…Our study focused on the changes of SOC stocks and soil aggregate stability. Given the Fe oxides produced by the corrosion of galvanized wire mesh can coprecipitate with the soluble organic carbon, and can also participate in the formation of soil aggregates as a cement (Feng et al, 2021; Sun et al, 2020; Xue et al, 2020), we hypothesized that CSG was more conducive to SOC stocks and has higher soil aggregate stability than CSN and CST. Furthermore, we predicted that aggregate‐associated SOC and soil aggregate stability may be the main drivers of SOC stocks changes (Zhong et al, 2021).…”

“…We observed that SOC stock in CST and CSG was significantly higher than that in CSN (Figure 4b). This may be improved soil quality of cut slope enhances the net primary productivity, and resulting in more plant and microbial residues input (Feng et al, 2021). Soil aggregates were important physical dimensions of SOC protection, and about 90% of SOC is stored in them (Sarker et al, 2018).…”

Nutrient addition affects stability of soil organic matter and aggregate by altering chemical composition and exchangeable cations in desert steppe in northern China

“…Our results showed that certain exchangeable polyvalent cations (e.g., Mg 2+ , Ca 2+ ) was positively related to WMD and proportions of macro‐aggregates, particularly small macro‐aggregates (Figure 8a). It has been reported that exchangeable Ca 2+ and Mg 2+ and was positively related to WMD in chernozem and saline‐sodic soils (Feng et al, 2021; Yao et al, 2022). Higher Ca 2+ content generally results in greater aggregate stability owing to the bridging of Ca 2+ , which forms clay‐polyvalent and metal–organic matter complexes (Chen et al, 2019; Rowley et al, 2017).…”