There was a huge forest fire here about 2008, not far from my house and on both sides of a major highway. They dumped foam fire retardant all over the place. NOTHING grew there for a good 10 years, and only now there's a tiny little bit of green vegetation starting.

Normally when there's a fire the soil is supercharged. 6 months later and the vegetation is so thick you can't walk through it. Not so after foam. Maybe they cracked open the barrels of agent orange by accident.