Erosion Control Toolbox: Decompact Soil Surface
Introduction
Decompaction of Soil Surfaces involves loosening compacted soils by pulling subsoiling equipment in successive passes in approximately perpendicular directions. It is typically performed via two methods: (1) Bulldozer-drawn winged subsoiler (as seen in the left-hand photo above) which is commonly used to decompact soils for agriculture; and (2) Tracked excavator equipped with a subsoiling grapple rake or excavator bucket (as seen in the right-hand photo above). Unlike bulldozer-drawn tilling, the grapple rake raises the soil surface slightly, leaving a small furrow on the surface. The grapple rake leaves the nutrient-rich surface layer intact, allowing water, microscopic fungi and plant roots to penetrate more deeply.
When to Use This Treatment
- Use on cut and fill slopes 3:1 and flatter. For specific maximum slope gradients, consult your geotechnical engineer
- Use on highly compacted soils that require tilling to restore infiltration, water holding capacity, and promote seed germination
- Consider using with compost and/or soil amendment to expand opportunities for cost-effective stormwater pollution control
Benefits
- Reduced stormwater runoff volume and velocity
- Improved infiltration rate
- Improved soil water holding capacity
- Improved soil structure, porosity and texture
- Improved plant rooting depth
- Improved potential for vigorous long-term vegetation coverage
- May increase effectiveness of Incorporate Materials when used in heavily compacted soils
Limitations
- More costly (yet more effective) than surficial treatments such as Erosion Control (Hydroseed and Hydromulch)
- May increase the cost of earthwork activities
- Requires site accessibility by earthwork equipment
- Not practical for shallow rocky soils, or if excessive soil moisture exists.
- Not cost effective for compacted clay soils
References
- Wendi Goldsmith, Marvin Silva, and Craig Fischenich. May 2001
- Caltrans Soil Compaction Webinar
Updated: October 1, 2021