The Role of Vegetation in Erosion Control
Areas affected by erosion or slope surfaces that have lost their organic structure are essentially zones without vegetation cover. These sites are especially threatened by rainfall, which triggers surface runoff, rill erosion, and eventually full erosion formation. Vegetation reduces the speed and droplet impact of rainfall, preventing direct contact with the soil surface. It regulates surface water flow, enabling infiltration into groundwater. Vegetation protects the soil surface from excessive surface water, supports drainage, and strengthens the soil through its root systems.
Herbaceous vegetation provides the lowest load per unit area while ensuring full soil stabilization. Through its natural biological activity, it increases the soil’s organic matter and supports long-term rehabilitation.
Revised Universal Soil Loss Equation (RUSLE)
During specific rainfall periods, computer-assisted calculations determine the soil loss per unit area using the RUSLE equation:
A = R × K × L × S × C × P
A = Calculated soil loss per unit area during a specific storm event
R = Rainfall erosivity factor
K = Soil erodibility factor
L = Slope length factor
S = Slope steepness factor
C = Cover-management factor (vegetation or mulch performance)
P = Support practice factor (erosion control applications)
A lower C Factor (Cover Factor) indicates better surface coverage and more effective erosion control.
High C Factor vs. Low C Factor
**Utah State University – Water Research Laboratory
Soil Loss Data per Acre (Extrapolated)**
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Unprotected Soil: ~ 75,000 lb/acre (High C = 1.0)
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Dry Straw: ~ 64,000 lb/acre
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Pellets (e.g., Encap PAM-12): ~ 62,000 lb/acre
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Seed Aide Aero Pellet: ~ 13,700 lb/acre
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Terra-Matrix (SMM): ~ 7,800 lb/acre
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Hydro-Mulch Blanket (BFM): ~ 3,900 lb/acre
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Flexterra (FGM): ~ 76 lb/acre (Low C Factor = 0.001)
Data includes a 1V sandy loam slope tested under large-scale rainfall for 5 hours 30 minutes.
Hydroseeding as the Fastest Way to Reduce the C Factor
Erosion control project areas typically consist of unprotected soils. The most rapid and effective intervention is to apply treatments that minimize the C-Factor.
Hydroseeding technology—when supported with the correct mulch and complementary materials—is currently recognized as the most effective erosion control method developed worldwide.