1) Protect the soil from the force of wind or water. 2)Stick more soil particles together, thus requiring more force for wind or water to carry it away. Biotic glues cement soil particles and organic matter into bigger clumps. Roots and fungal hyphae holds these bigger clumps together like a thin-mesh net. This is called a macroaggregate. Macroaggregates are heavier and less susceptible to be picked up by the wind, especially when protected by a plant. Also, water now tends to soak into the ground quicker and fall between these macroaggregates in vertical fashion, not horizontal. Organic matter attracts water extremely well, so each macroaggregate sucks up water if there is room for it. Voila! Now you know why it takes hurricane force winds and Noah-like deluges to erode well-aggregated soil protected above by plants.

https://cra.missouri.edu/wp-content/uploads/2021/09/Cover-crops-controlling-erosion.pdf

“Erosion predominantly transports clay and organic matter fractions of the soil (which are relatively rich in phosphorus), leaving behind the coarser, lower-phosphorus fractions. Thus, compared to the original soil, eroded sediment often has more than twice the concentration of phosphorus – an enrichment ratio of 2 or more being typical” Brady and Weil page 670