This quote if from an interesting ISU article on soil conservation and how important it is to have good practices in place for the spring of the year.
"Why is rainfall so destructive to bare cropland? In a normal rainfall, raindrops range in size from 1 to 7 millimeters in diameter and hit the ground going as fast as 20 miles per hour (see photo). The impact of millions of raindrops hitting the bare soil surface can be incredible, dislodging soil particles and splashing them 3 to 5 feet away (Figures 1 and 2). A heavy rainstorm may splash as much as 90 tons of soil per acre. However, the majority of the soil splashed is not immediately lost from the field. Most of the splashed soil particles don't leave the field; they clog surface pores which in turn reduces water infiltration, increases water runoff, and increases soil erosion."