How to Treat Soil After a Fire

A fire can severely damage soil.

Fires, whether in the home or in the surrounding lawn or trees will likely cause soil damage. Soil is damaged by the heat created by the fire. Chemically, the soil will lose organic matter, and it will have reduced porosity and and increased pH. This makes the soil infertile and increases erosion of the topsoil from the area. Your main goal after a fire will be to keep erosion of the soil to an absolute minimum.

Things You'll Need

• Aerator
• Grass seed
• Grass seed spreader
• Rake
• Garden roller
• Straw
• Long logs or tree trunks

Instructions

1. Place drops of water on the soil. Inspect whether they bead up or penetrate the soil. If the water beads it is hydrophobic, meaning a waxy layer has built up on the soil that causes water to be repelled. Remove one inch of soil at a time and repeat the test until you find a water-absorptive layer.

2. Aerate the area with an aerator to the depth where the soil is not hydrophobic. Aerators are available for rent from most garden centers. Run the aerator left to right, then up and down the area for a good coverage.

3. Broadcast grass seed over the area using a grass seeder at a rate of 10 to 20 lbs. per acre (43,560 square feet).

4. Rake the area 1/4 to 3/4 inch depth. Tamp down the area with a garden roller to ensure the seeds touch soil.

5. Pull up any noxious weeds. Ask your university extension for a chart of noxious weeds for the area. They are often the first to appear after a fire.

6. Spread a 2 to 3 inch uniform layer of straw to protect the seed from blowing away and to retain moisture.

7. Lay long logs or tree trunks across any hills in the area in brick pattern to keep soil from rolling downhill during heavy rains.

References

• Colorado State University Extension; Soil Erosion Control after Wildfire; R. Moench and J. Fusaro
• British Columbia: Fire Effects on Soil