On land that is not forested we can gauge the amount of rain that soaks in or infiltrates the landscape, as well the amount of rain that will run off and erode the soil, with the appropriate amount of vegetative cover.
1.2% rainfall will soak in at 5% vegetative cover
1.5% rainfall will soak in at 15% vegetative cover
1.7% rainfall will soak in at 25% vegetative cover
2.4% rainfall will soak in at 35% vegetative cover
If we cover these areas with 65-70% vegetation we can totally prevent soil loss and erosion. Wheat grass is a wise and sustainable starting point.