Which treatment involves applying chemical barriers in the soil?

The correct answer involves the application of a pesticide solution directly into the soil, creating a barrier that prevents termites from entering the structure. This method is specifically designed to target and inhibit termite movement through the soil, effectively protecting buildings from potential infestations. Soil treatment is often performed during the construction phase of a building or as a preventative measure for existing structures.

Fumigation involves sealing a building and using gaseous pesticides to eliminate pests within, but it does not focus on creating a barrier in the soil. Spot treatment, on the other hand, is a targeted approach that addresses visible infestations rather than establishing preventive measures in the soil. Lastly, gas treatment refers to the use of gas pesticides, which are not applied to the soil but are instead utilized in enclosed spaces to eradicate pests.