5.3.4 Vegetative Cover Factor

      The vegetative cover factor (C-factor) is defined as the ratio of soil loss from land under specified vegetative or mulch conditions to the corresponding loss from tilled, bare soil (Goldman et al. 1986). Any vegetation or management condition that reduces the amount of soil exposed to raindrop impact will reduce erosion. In the USLE, the C-factor reduces the soil loss estimate according to the effectiveness of vegetation and mulch at preventing detachment and transport of soil particles. The effect of vegetation on erosion rates results from canopy protection, reduction of rainfall energy, and protection of soil by plant residues, roots, and mulches. When the surface is bare, the C-factor is considered to equal unity.

      Typical values for C-factors are presented in Table 5.11. Many reports have been published defining the C-factor for numerous vegetative conditions. These documents include Goldman et al. (1986), Shultz et al. (1986); Mills et al. (1985), Kay (1983), Novotny and Chesters (1981), Mitchell and Bubenzer (1980), Wischmeier and Smith (1978, 1965), USDA (1975), Stewart et al. (1975), and Wischmeier (1976).