Abstract:

The problem of global soil salinization is becoming increasingly serious, leading to the decline of soil productivity, inhibition of plant growth, threats to food security, and economic losses. Consequently, it poses a significant threat to agricultural production and ecological balance. Due to its unique properties such as expansibility, high water absorption and ion exchange, bentonite water-retaining agent has shown great potential in improving saline-alkali land. It can enhance soil aggregate structure, reduce soil bulk density, regulate water and salt migration, reduce salt accumulation on the surface and mitigate the soil hardening caused by salinization. Moreover, it provides a more favorable growth environment for soil microorganisms and plants. Therefore, it is considered as a promising material for soil remediation. In this study, the literature related to bentonite water-retaining agent retrieved from Web of Science and CNKI was systematically analyzed using bibliometric methods. Specifically, the structural characteristics of bentonite water-retaining agent and its effects on water and salt migration in saline soils were summarized. In addition, the application outcomes of bentonite water-retaining agent in improving soil structure, enhancing nutrient utilization efficiency, promoting microbial activity and increasing crop yield were evaluated. Furthermore the potential applications and limitations of bentonite water-retaining agent were discussed. The results showed that bentonite water-retaining agent could increase the stability of soil aggregates in saline-alkali soil by 15%-30%, and the uptake of nitrogen, phosphorus and potassium by crops by 20%-40%. The bentonite water-retaining agent has significant synergistic advantages of ‘water absorption-salt suppression-ecological friendliness' and is a potential material for saline-alkali land improvement. Future research can focus on the composite modification and multi-functional synergistic application of bentonite water retaining agent to further improve its water retention, salt regulation and nutrient synergistic regulation ability, in order to provide theoretical support for low-cost, environmentally friendly improvement and sustainable agricultural development of saline-alkali land.

Key words: saline-alkali land, bentonite water-retaining agent, ion adsorption, water-salt migration, ion exchange