Cover crops do more than remove nitrates. Cover crops that farmers plant in the fall to capture nitrogen also reduce soil erosion by holding soil with live roots that increase the fungi and bacteria that improve soil health. Bacteria in the soil are the reason that soil produces nitrogen. Bacteria use the soil organic matter (dead plant residue) and fungi living in the soil, as the fungi die they release nitrogen. Soil water infiltration is improved so rainwater is absorbed by the soil. Runoff is reduced.
Keeping soil in farmers’ fields reduces sediment in lakes and rivers and reduces the fertilizer that farmers buy to replace nutrients that the cash crop removes.