Dry Mulch
What – Straw, woodchips or fiber materials are applied to burned areas using ground or aerial application.
Purpose – By providing immediate ground cover, mulch is intended to reduce surface erosion, reduce downstream peak flows by absorbing rainfall, and secure seeds stored in the soil or applied as emergency treatment. Mulch also provides favorable moisture and temperature regimes for seed germination.
Effectiveness – Straw mulch was reported as highly effective in reducing surface erosion when application rates exceeded 60% ground cover, and sometimes effective in reducing runoff. Sites prone to high winds reported reduced effectiveness. A combination of mulching and seeding was reported as more effective than seeding alone in regards to germination, but not necessarily in regards to surface cover. Wood based mulches (manufactured products and shredded on-site trees) were equal to or more effective than straw mulch in reducing post-fire erosion.
Where
- Areas with moderate- or high-burn severity.
- Due to cost, there usually needs to be prioritization for mulch application, focusing on where there is a threat to life and property. This may include steep slopes adjacent to communities, roads, and infrastructure; critical headwaters that feed municipal water supplies; and waste sites that pose serious environmental threats.
Cost – Straw aerial application $250–930 per acre; ground application $425–1200 per acre. Based on 1–2 tons per acre application rate (provides average mulch depth of 1–2 inches). Wood based aerial application $1500–2000. Additional factors include:
- Location and access.
How to Link – See USDA BAER Catalog page 27 (PDF page 35).