by Russell Taylor
The destruction of soil organic matter (SOM) during large-scale wildfires, such as those in California's Palisades area, creates significant challenges for soil health and ecosystem recovery. Environmental health experts warn Angelenos as they return to what is left of their homes and businesses to protect themselves from harmful toxins not only in the air but also in the soil.
Here’s a breakdown of the fire-related impacts and the potential solutions for healing the soil and restoring SOM in these areas:
Destruction of Soil Organic Matter in Wildfires
Heat Impact—Wildfires burn off surface organic matter, including plant debris, roots, and decomposing materials. Extreme temperatures destroy critical carbon, nitrogen, and other nutrients essential for soil fertility.
Even slow organic matter (stable humic substances), which resists microbial decomposition, can be damaged or volatilized under prolonged or intense heat.
Loss of Soil Structure—SOM plays a critical role in binding soil particles together, improving structure and porosity. Its destruction results in compacted, poorly aerated soils that are less conducive to plant and microbial life.
Ecosystem Impacts—Reduced SOM decreases the soil's water retention capacity, limiting its ability to support vegetation regrowth.
Soil microbial populations, essential for nutrient cycling, are often severely diminished, disrupting ecosystem functions.
Erosion and Runoff—Without SOM and vegetation cover, soils are vulnerable to erosion. Wind and water can strip away nutrient-rich topsoil, exacerbating degradation.
Need for Additional Soil Organic Matter
The steep terrain of the Palisades is particularly prone to erosion and water repellency post-fire. Restoring SOM is essential for soil stabilization and ecological recovery. Here’s how and why it should be prioritized:
Adding organic matter such as compost, humates, or well-decomposed manure can restore SOM, improving structure, aeration and microbial activity.
The addition of humic substances can boost nutrient availability and enhance plant establishment.
Erosion Control—Organic mulches or erosion-control blankets can protect the soil surface from rainfall impact and reduce sediment loss. These materials also help establish cover crops or native plants, stabilizing soil over time.
Improving Water Retention—SOM increases the soil’s capacity to retain water, a critical factor in the drought-prone conditions often seen after fires in California.
Mitigating Hydrophobicity—Fire-induced water repellency can be reduced by applying organic matter, which helps break down hydrophobic compounds and improves water infiltration.
Practical Recommendations
Immediate Actions—Apply mulches or compost to protect exposed soils and prevent further erosion.
Use liquid humates or other highly soluble organic amendments to encourage microbial activity and nutrient cycling.
Long-Term Strategies—Reintroduce SOM by spreading compost, manures, or humic-rich materials to rebuild soil organic carbon pools.
Plant cover crops, such as native grasses or legumes, to stabilize soils and provide organic inputs over time.
Monitoring and Assessment—Conduct soil tests to evaluate the extent of SOM loss, nutrient imbalances, and structural damage.
Adjust restoration efforts based on soil type, erosion risk, and vegetation recovery progress.
The Role of Humates—Humates, composed of humic and fulvic acids, are especially effective in restoring fire-damaged soils, and support “nutrient cycling.” They chelate nutrients, improving their availability for plant uptake. They also improve water-holding capacity: Humates improve soil porosity and enhance moisture retention. Additionally, humates provide microbial support. They provide a food source for beneficial soil microbes, jumpstarting the recovery of soil ecosystems.
Restoring soil organic matter post-fire in the Palisades and elsewhere is vital for long-term ecological resilience. The targeted application of humates, compost, and other organic amendments can help rebuild SOM, stabilize soils, and promote vegetation regrowth, ensuring sustainable recovery for these fire-impacted landscapes.
About the author: Russell Taylor is VP of Live Earth Products and “Conservationist of the Year.” To learn more, visit Live Earth online or contact Live Earth at (435) 286-2222.
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