Soil Erosion Calculator Formula

Understand the math behind the soil erosion calculator. Each variable explained with a worked example.

Use the Soil Erosion Calculator

Formulas Used

Annual Soil Loss

erosion_rate = annual_loss

Annual Soil Loss per Acre

erosion_per_acre = annual_loss / 2.471

vs Soil Tolerance (5 t/ha)

vs_tolerance = annual_loss / 5 * 100

With Best Practices (P=0.3)

with_best_practice = r_factor * k_factor * ls_factor * c_factor * 0.3

Variables

VariableDescriptionDefault
r_factorRainfall Erosivity (R)(MJ*mm/ha/hr/yr)200
k_factorSoil Erodibility (K)(ton*hr/MJ/mm)0.03
ls_factorSlope Length & Steepness (LS)2
c_factorCover & Management (C)0.3
p_factorConservation Practice (P)0.8
annual_lossDerived value= r_factor * k_factor * ls_factor * c_factor * p_factorcalculated

How It Works

How to Calculate Soil Erosion (USLE)

The Universal Soil Loss Equation estimates average annual soil erosion.

Formula

A = R * K * LS * C * P

  • R = Rainfall erosivity
  • K = Soil erodibility (sandy=0.02, loam=0.03, clay=0.04)
  • LS = Slope length and steepness (flat=0.5, moderate=2, steep=5+)
  • C = Cover management (forest=0.01, grass=0.1, bare=1.0)
  • P = Conservation practice (none=1.0, contour=0.5, terracing=0.1)

    • Soil loss tolerance is typically 5 tons/ha/year for sustainable agriculture.

    Worked Example

    Farmland with R=200, K=0.03, LS=2, C=0.3 (row crops), P=0.8 (minimal conservation).

    r_factor = 200k_factor = 0.03ls_factor = 2c_factor = 0.3p_factor = 0.8
    1. 01Soil loss: 200 * 0.03 * 2 * 0.3 * 0.8 = 2.88 tons/ha/year
    2. 02Per acre: 2.88 / 2.471 = 1.17 tons/acre/year
    3. 03vs tolerance: 2.88 / 5 * 100 = 58% of limit
    4. 04With best practices (P=0.3): 200 * 0.03 * 2 * 0.3 * 0.3 = 1.08 tons/ha/year

    Ready to run the numbers?

    Open Soil Erosion Calculator