Combined application of organic wastes and Trichoderma longibraciatum to promote vegetation restoration and soil quality on mining waste dump sites

Vitamin C industrial organic fermentation waste—residue after evaporation (RAE) and Trichoderma longibraciatum (TL) can provide organic acids and microorganisms for soil amendment. This study assessed the feasibility of RAE and TL to improve soil nutrients and accelerate vegetation recovery in mining waste dump sites (MWDS).

The trial included four treatments: (1) CK (control); (2) R (RAE addition); (3) T (TL addition); and (4) RT (RAE and TL addition). The improvement potential of RAE and TL was assessed by examining soil nutrients, enzyme activity, microbial communities, and physiological changes in perennial ryegrass (Lolium perenne L.).

Compared to CK, RT significantly improved the biomass, the stress and lodging resistance of perennial ryegrass. RT significantly increased the organic matter, available nitrogen, available phosphorus and available potassium content, and significantly enhanced the soil urease and phosphatase activities in MWDS soils. The Shannon and Ace indices of RT were not improved, but RT increased the relative abundance of Sphingomonas, Devosia, and Flavobacterium.

The positive synergistic effect of RT on perennial ryegrass growth resulted from the combined impacts on plant physiology, soil nutrients and bacterial community structure. RT is well-suited for improving the soil quality and accelerate vegetation recovery in MWDS.