Fig. 2. Representative soil cylinder with residues in the center and surface seal in the remaining area (Type I). R₁ is the radius of the residue patch. R₂ is the radius of the soil cylinder. D is the depth of the soil cylinder. Water may first run on to a residue-covered area from a surface-sealed area. Excess water from both the residue-covered area and surface-sealed area then become runoff, which is removed from the system