Soil Conservation Lab

Investigate how slope steepness, soil type, vegetation cover, and conservation practices interact to control soil erosion. Collect data across multiple trials using the USLE model, analyze erosion patterns, and evaluate the effectiveness of practices like terracing, contour farming, and cover crops.

Guided Experiment: Effect of Slope on Erosion

Hypothesis

Setup

Run Experiment

Analyze

Conclude

If you increase the slope steepness while keeping soil type and land cover constant, what do you predict will happen to the erosion rate?

Write your hypothesis in the Lab Report panel, then click Next.

Hillslope View

Controls

Presets

Slope Steepness10%

Annual Rainfall800 mm

Slope Length75 m

Soil Type

Land Cover

Conservation Practice

Results

A = R \times K \times LS \times C \times P = 513.43 \text{ t/ha/yr}

R Factor

2279.9

K Factor

0.300

LS Factor

2.14

C Factor

0.350

P Factor

1.000

Baseline

1466.93

Erosion Risk Level

Severe

513.43 t/ha/yr

Reduction from Bare Soil Baseline

65.0%

Erosion vs Slope by Land Cover

Data Table

(0 rows)

#	Trial	Slope(%)	Soil Type	Land Cover	Conservation Practice	R Factor	Erosion Rate(t/ha/yr)	Reduction(%)

Hypothesis

0 / 500

Observations

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Conclusions

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Reference Guide

The USLE Model

The Universal Soil Loss Equation estimates average annual soil erosion from a hillslope. Each factor isolates one driver of erosion.

A = R \times K \times LS \times C \times P

R Rainfall erosivity
K Soil erodibility
LS Slope length and steepness
C Cover management
P Conservation practice

Slope and Erosion

The LS factor captures the combined effect of slope length and steepness. Steeper slopes generate faster runoff with greater erosive power.

LS = \left(\frac{\lambda}{22.13}\right)^m (0.065 + 0.045S + 0.0065S^2)

Where $\lambda$ is slope length in meters, $S$ is steepness in percent, and $m$ ranges from 0.2 to 0.5 depending on slope. The squared steepness term means doubling slope more than doubles erosion.

Soil Erodibility (K Factor)

Different soil textures resist erosion differently. K values range from 0.02 (resistant) to 0.7 (highly erodible).

Soil Type	K Factor
Sandy	0.15
Clay	0.22
Loamy	0.30
Silty	0.45

Silty soils are the most vulnerable because fine particles detach easily and lack the binding cohesion of clay or the weight of sand.

Conservation Strategies

Conservation practices reduce erosion by slowing runoff, trapping sediment, and protecting the soil surface.

Terracing (P = 0.10) breaks long slopes into short, level steps, reducing effective slope length and speed
Cover crops (P = 0.25) protect soil between main crop seasons with roots that hold soil in place
No-till (P = 0.25) leaves crop residue on the surface to shield soil from raindrop impact
Contour farming (P = 0.50) plows furrows across the slope instead of downhill, creating ridges that slow runoff
Buffer strips (P = 0.35) are bands of permanent vegetation that filter sediment from runoff before it reaches waterways