First oil, as I recall, the gravel roads were even getting treatments of that, then calcium chloride, but we were told it made the horses hooves soft, so that went away, then came liquid soap, I'd hate to say how many gallons of that I put down, then all of a sudden it was gone, too expensive so we were told. I have a hard time believing any of it, but looks like water is it, and if it's coming from a nearby creek, it's got more dust in it than the track had to start with!