Soil Loss Assessment Using the Revised Universal Soil Loss Equation (RUSLE) Model
Table 2
The K factor algorithms.
Equation
Reference
Serial number
, where A1 = % unstable aggregates less than 0.250 mm A2 = product of % silt (0.002–0.01 mm) and % sand (0.1–2 mm) A3 = % base saturation of the soil A4 = % silt (0.002–0.050 mm) A5 = % sand (0.1–2 mm) Units for K: Mg h MJ−1 mm−1
, where K = soil erodibility factor (t hr−1ha−1MJ mm), m = (silt % + sand %) × (100 − clay %) a = percent organic matter b = soil structure code: (1) very structured or particulate, (2) fairly structured, (3) slightly structured, and (4) solid c = soil profile permeability code: (1) rapid, (2) moderate to rapid, (3) moderate, (4) moderate to slow, (5) slow, and (6) very slow Soil organic matter is derived by the following equation: SOM = 1.72 ∗ OC [99], where SOM = soil organic matter OC = soil percentage organic carbon content
, , where = geometric mean diameter of the soil particles (mm) fi = weight percentage of the particle size fraction (%) mi = arithmetic mean of the particle size limits (mm) n = number of particle size fractions
, , where = Napierian logarithm of the geometric mean of the particle size distribution OM = organic matter content (%) Cl = clay fraction (%) fi = mass fraction in the corresponding particle size class (%) n = number of particle size fractions di = maximum diameter of the ith class (mm) di−1 = minimum diameter (mm)