From waste to soil: The pivotal role of organic matter in soil aggregate formation under dry and wet conditions

Background and aims

Coal tailings, given their limited ecological functionality, frequently necessitate the investigation of innovative resource utilization methods. Soil aggregates, fundamental to soil structure and function, rely heavily on the content of organic matter and moisture during their formation. However, the impact of soluble and insoluble carbon sources on the durability and stability of aggregates under varying wetting conditions remains unclear.

Methods

This study employed kaolinite, a primary component of coal tailings, as a control to examine the formation of large aggregates of tailings under varying organic matter conditions and the stability of these aggregates under wet and dry conditions.

Results

A comparison of coal tailings with high organic matter content to kaolinite, which lacks organic matter, reveals that soluble carbon can significantly and rapidly augment the content of large soil aggregates, particularly under slow wetting treatment conditions, where its content surpasses 3 times that of other treatment groups. The diffusion of insoluble carbon can bolster the aggregation of soil aggregates under both dry and wet conditions. Small soil particles decelerate the decomposition of organic carbon, markedly impacting the stability of the aggregate structure.

Conclusion

The inherent organic matter in the tailings matrix, along with the physicochemical mechanisms dominated by the form of substances (soluble or insoluble), can elucidate the stability process of large aggregates. This study offers a scientific foundation for exploring the field of solid waste resource utilization and soil structure.