A compost blanket is a layer of compost applied on the soil surface as a mulch, typically at a depth of 2 inches or 270 cubic yards per acre. A compost blanket protects soil surfaces from wind and water erosion, conserves water, and moderates soil temperature. In addition, a compost blanket improves the soil’s physical, chemical, and biological properties, which provides a healthy growth medium, including nutrients, required for sustainable plant establishment.
Seeded Compost Erosion Control Blanket, photo courtesy of Filtrexx
Where to Use Compost Blankets
Use compost blankets where:
- Construction or other land disturbing activities are completed
- Soil is compacted and/or where soil organic matter (SOM) and nutrients are low and permanent vegetation is required
- Treatment of stormwater runoff is required
- Reduction of runoff volume is needed to allow reduction in size of stormwater collection, bioretention ponds, and rain gardens
Suggestions to Maximize Performance
- Apply a depth of 2 inches or 270 cubic yards per acre. An engineer may recommend application of a thicker blanket for additional reduction of runoff volume during large storm events.
- Install irrigation to ensure vegetation establishment.
- Install stormwater runoff diversion devices to prevent erosion and washing away of seed prior to vegetation establishment.
- Use additional stabilizers or support practices such as netting on slopes greater than 2:1.
- Compost should meet product quality specifications
- Compost blanket should meet performance and design specifications appropriate for site conditions and goals.
Benefits of Compost Blankets
- Reduces erosion
- Provides plant nutrients in a stable, organic form
- Reduces stormwater runoff and velocity
- Increases water holding capacity
- Increases infiltration rate
- Conserves water
- Improves soil biology
- Provides plants with a healthy growth medium
Design Considerations
- Determine if new slopes will require incorporation of organics to support sustainable vegetation.
- Specify “Medium” or “Coarse” compost materials for compost blanket work to minimize the loss of compost due to wind.
- Consider combining compost blanket with netting or hydromulch on steep slopes.
- Consider treating sites with compacted, sterile, or poorly draining soils by combining compost blanket with local topsoil or incorporation of compost into soil.
Specifications
CalRecycle regulations require that compost produced by commercial scale composting operations and facilities meet maximum metal concentrations, physical contamination limits, and pathogen reduction standards. CalRecycle requirements are minimum standards and local jurisdictions or other specifiers may have requirements that are more restrictive.
Common Compost Application Rates
| Depth (inches) | Cubic Yards/Acre | Cubic Yards/ 1,000 sq. ft. |
|---|---|---|
| 0.5 | 67 | 1.5 |
| 1.0 | 134 | 3.0 |
| 2.0 | 269 | 6.0 |
| 3.0 | 402 | 9.0 |
Note: tonnage varies based on compost bulk density.
See Caltrans Erosion Control Toolbox for compost application methods for compost blankets and additional information.
Resources
- USEPA Stormwater Best Management Practice – Compost Blankets EPA Compost Blanket Stormwater BMP
- California Stormwater Quality Association (CASQA): Compost blanket (EC 14)
- Filtrexx Storm Water Blanket Filtrexx Compost Storm Water Blanket
Research
- Faucette, L.B. et al (2006). Vegetation and soil quality effects from hydroseed and compost blankets used for erosion control in construction activities. Journal of Soil and Water Conservation. 61(6):355-362.
- Faucette, L.B. et al (2007). Erosion control and storm water quality from straw with PAM, mulch, and compost blankets of varying particle sizes. Journal of Soil and Water Conservation. 62(6):404-413.