Mulch is a soil covering used to control weeds, provide erosion control, retain moisture in soil, insulate soil from temperature extremes, and improve aesthetics.
Organic materials commonly used for mulch include wood chips, ground up landscape trimmings, shredded bark, coarse compost material, straw, and shredded paper.
Non-organic materials include crushed concrete and brick, stones and gravel, lava rock, and plastic film. For purposes of this toolbox, mulch is only organic materials.
Where to Use Treatment
- Agriculture
- Landscapes
- Typically applied on slopes 2:1 (H:V) and flatter
- Use to reduce raindrop splash erosion and competition from weeds
- Typically applied 2″-3” deep (270-400 cubic yards/acre)
Benefits
- Provides erosion control
- Reduces weeds
- Conserves water
- Moderates soil temperature
- Improves aesthetics
- Increases infiltration rate
- Easy application by pneumatic blower trucks or bulldozers (in flat areas)
Limitations
- Requires temporary storage space within the project limits to stockpile materials
- Applying high levels of organic materials may not be appropriate in arid regions of the state
- Functional longevity of less than three years
- Shredded mulch may be required for steep slopes
Consider Using With
At sites with poor soils (compacted, nutrient depleted, or poorly draining), consider combining this treatment with local topsoil, compost blanket, or incorporating compost into soil.
Plans and Details
- Planning and Designing Your Home Landscape
- Guide to sheet mulching: Marin Sheet Mulching Guide
Specifications
- CalRecycle Compost and Mulch Use Toolbox on Product Quality and Specifications
Resources
- Using mulch to help trees survive the hot summer. Sacramento City Parks Mulch Madness.
- Bay friendly guide to grow gardens and build healthy soils
- Caltrans Mulch Webpage
- CalRecycle webpage on agricultural demonstration projects, includes mulch demonstration project reports
Research
- van Donk, S.J., D.T. Lindgren, D.M. Schaaf, J.L. Petersen and D.D. Tarkalson. 2011. Wood chip mulch thickness effects on soil water, soil temperature, weed growth and landscape plant growth. Journal of Applied Horticulture. 13(2):91-95.
- Khurshid, K., M. Iqbal, M.S. Arif, and A. Nawaz. 2006. Effect of Tillage and Mulch on Soil Physical Properties and Growth of Maize. International Journal of Agriculture and Biology. 8(5):593-596.
Resources
For more information contact: Organic Materials, organics@calrecycle.ca.gov