Ants communicate with each other using pheromones, sounds, and touch. Since most ants live on the ground, they use the soil surface to leave pheromone trails that may be followed by other ants.
To communicate with each other, ants use a combination of pheromones, sound, and touch.  Since most ants reside on the ground, they employ soil as a medium for leaving scent trails that other ants can detect.