How do fungi improve soil quality?
Fungi increase soil aggregation and soil organic carbon. The increase in soil aggregation is attributed to glomalin, a substance that fungi make and coat themselves with that helps them stick to the soil. Glomalin stays in the soil giving it texture long after the fungi die. The texture glomalin contributes prevents erosion and creates porosity that improves filtration and oxygenation of the soil. The increase in soil carbon is due to the fact that fungi have a higher C:N ratio than the nitrogen rich bacteria and so when they die they are the main contributors to stored soil organic carbon.
Six, J., Frey, S. D., Thiet, R. K., & Batten, K. M. (2006). Bacterial and fungal contributions to carbon sequestration in agroecosystems. Soil Science Society of America Journal, 70(2), 555-569