Bare ground is exposed soil that is susceptible to unimpeded raindrop impact. Direct raindrop impact on soil represents the greatest erosive force on grazing land; cover of standing vegetation and plant litter is therefore vital for dissipating the erosive energy of raindrops. Cover and soil structure tend to be greatest under trees and shrubs, followed in decreasing order by bunchgrass, shortgrass, and annuals. The interrill (splash) erosion rate follows the same pattern, being lowest under trees and shrubs and highest under short-grass and annuals. Grazing practices that increase the amount of bare ground or contribute to a shift in species composition toward dominance of shortgrass species or annuals result in an increased incidence of inter-rill erosion.
A common indicator of interrill or wind erosion are pedestals of soil under impermeable cover such as rocks or plants that appear elevated over the rest of the terrain. Some of the particles that are detached by raindrop impact clog the pore spaces in the soil. This is a common way that soil crusts are formed. Crusts cause a significant reduction of water movement into the soil, thereby substantially increasing runoff.
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