# Progress and Prospect of Saline-Alkaline Soil Management Technology: A Review
## 3 Advanced Technology of Saline-Alkaline Soil Management
### Emerging Chemical Treatments
#### 3.2.2 Humic Acid  
Humic acids are organic colloids with high activity, adsorption, and aggregation capabilities. These properties enable humic acid to make a crucial role in the treatment of saline-alkaline and alkaline land. Specifically, humic acid helps disperse soil particles, enabling them to agglomerate tightly [92]. This process not only improves soil architecture and the capacity to retain moisture and nutrients, but also enhance soil aeration and water permeability, providing a better environment for plant growth.  
Humic acid, a macromolecular organic substance, is derived from animal and plant remains. These remains accumulate to form humic acid through a complex array of chemical reactions during microbial decomposition and metamorphosis processes [93]. In recent years, this research has advanced significantly.  
[PERSON] et al. [94] discovered that the application of earthworm castings and humic acid fertilizers significantly improved the microstructure of large aggregates in saline-alkaline and alkaline land. Humic acid fertilizers can also enhance bacterial and fungal activity, especially during harvest stage when nutrient availability and root nutrient adsorption improve in saline-alkaline soils [95]. These fertilizers also increase the yield and quality of crops like sugar beets, with reported increases in yield ranging from 11.29% to 32.54% and sugar production from 13.5% to 38.61% [4].  
[PERSON] et al. [96] discovered that, under salt stress, humic acid boosted the photosynthetic rate, transpiration rate, and stomatal conductance of switchgrass, while lowering intercellular CO\({}_{2}\) concentration. This enhancement significantly promoted switchgrass growth by optimizing its photosynthetic function. In a separate study, [PERSON] et al. [97] found that incorporating granular corn stover into saline-alkaline and alkaline land notably increased the soils humus content and composition.  
Furthermore, humic acid can significantly improve the soil's structural and chemical properties. It can regulate soil acidity, making it more suitable for plant growth. Rich inorganic matter, minerals, and micronutrients, humic acid is essential for plant growth and development. As a macromolecule organic matter and organic colloid, humic acid has important application value in soil, as it improves soil structure, physical and chemical quality, enhances soil fertility, and boosts productivity, thereby supporting sustainable agricultural development [98; 99].  
While chemical amendments provide rapid improvement in soil properties, their long-term effectiveness and potential for secondary pollution need to be carefully considered. A combined approach that includes both chemical and organic materials has been found to be more effective for improving the health of saline-alkaline soils [100]. However, it is important to evaluate the environmental impact of chemical measures, particularly considering the risk of contamination from exogenous materials like calcium containing compounds, humic acid, and furfal residue, which are commonly used in saline-alkaline soil amendments [37].