The potential for soil erosion after a fire can be dramatic.
Slow moving fires are very hot and can cause a condition called hydrophobicity where the soil will repel water. This hydrophobic condition will increase water runoff on slopes and reduce water percolation. This will cause soil erosion and make it difficult for seeds to germinate and for surviving plants to get moisture.
Fast moving fires may not create a hydrophobic condition.
After a wildfire, reseeding with grasses in the severely burned areas can help to alleviate soil erosion. Many plants that burned in a fire can recover depending on the severity of the burn. If possible leave existing vegetation intact.
Seeding Tips for Hand Planting
If a hydrophobic soil is present the seedbed needs to be roughened to allow the seed to break through. A steel rake works well for this or, depending on the slope, a small tractor drawn harrow could be used.
Broadcast the seed (a "Cyclone" seeder works well). Seeding rate is 10lb. for up to 20,000 Square Feet.
If possible rake or harrow in 1/4 inch to 3/4 inch deep. Compress or roll the seeded area when possible to ensure good soil/seed contact.
Spread mulch or compost or hay over the seeded area if possible.
Control weeds as needed. Do not use herbicides for broadleaf weed control until the grass has developed at least five leaves.
Weeds are always the first to emerge after a fire. Quite often they do not present a problem unless they are noxious weeds. There are many ways to control weeds by chemical, biological, mechanical and cultural methods.
If you are broadcasting straw use enough to cover the reseeded area at a depth of 2 to 3 inches. Straw will provide a protective cover over the seeded area to help reduce erosion and create an environment for seed germination. Use only certified weed-free hay straw to avoid spreading noxious weeds.
Straw folded into the soil will hold the soil in place the best and slow down run off water much better than exposed soil. It will help to reduce runoff and increase water infiltration.