What is an effective method to stop the spread of a ground fire?

Digging a trench is an effective method to stop the spread of a ground fire because it removes the combustible material that the fire relies on to continue burning. By creating a barrier of bare earth, a trench interrupts the fire's fuel supply. This method is particularly useful in preventing the fire from spreading horizontally across the ground, especially in areas with dry vegetation or other flammable materials.

While wetting the area can help suppress fire by reducing heat and humidity, it might not be as effective for a ground fire that's already well-established. Setting a backfire can also be a strategic tool; however, it is a more advanced tactic that involves creating a fire intentionally to deprive the main fire of fuel and can be risky. The use of fire retardant is more applicable in aerial firefighting or specific controlled scenarios, making it less suitable for direct intervention on the ground to halt the immediate spread of a ground fire. Thus, digging a trench stands out as a practical and immediate course of action against ground fire spread.