PurposeThis study aims to investigate the effects of root exudates on the aggregate stability and permeability of loess and to further reveal the mechanisms of vegetation in preventing and controlling soil erosion beyond mechanical effects.Materials and methodsWetting tests were conducted to investigate how loess aggregate stability varies with curing time and root exudate concentration; and infiltration tests were carried out to examine the influence of root exudates on the infiltration characteristics of loess with varying degrees of compaction.Results and discussionThe results showed that the stability of loess aggregates significantly increased due to the application of root exudates. Curing could enhance the stabilizing effects of root exudates on loess aggregates; however, there existed a critical curing duration. The application of root exudates reduced the stable infiltration rate and hydraulic conductivity of loess. However, untreated specimens under lower degrees of compaction exhibited lower stable infiltration rate and hydraulic conductivity due to local structural damage. The stable infiltration rate of both treated and untreated specimens decreased with curing time.ConclusionsThe effects of root exudates can be attributed to their ability to function as stabilizing agents and promote aggregation, due to their high adsorption capacities and negatively charged groups on their surfaces. On the other hand, the presence of root exudates can significantly enhance the soil microbial activity, the microorganisms and their hyphae further strengthen the soil structure, fill pores and increase the soil hydrophobicity, thereby improving the aggregate stability while reducing the soil permeability.
