I've noticed the ants have been less of a problem in our yard for about two years. They're very localized to only a few places in the yard this year. Under the deck where my shed is, is their last bastion. We also had the house treated with an orange oil to help get rid of termites about 2 years back as well. Maybe a connection, but the soil is certainly changing things. I see ants in a few of my large pots once in a while, but mostly they're becoming less of a problem.