Actually, I like that potting soil idea.
I always assumed, and maybe my Zombie knowlege is off here, that after a few weeks they all decay enough that all they can do is sort of "twitch" and then they fall appart. We seal about 20 men and 400+ beautiful women (ah la "Dr. Strangelove") in a safe place, let the zombies take down most of the rest of the population, and suddenly there's no un-employement, we've cut resource needs way down, the Earth can Recover. As the one who came up with this idea, I should be one of the 20. Those not in the "safe haven" will be the survivors, the quick to think and move, the ruthless. Hell of a way to clean out the gene pool!
Without zombies, we are talking about 10 billion people in another 35 years or so. Can't use Vampires, they like things just like the "living" and will continue to consume just like the present population. Nope, gotta be Zombies. A plate of brains, and they are happy. Decay and maggots takes care of the rest in a few weeks or so.
Earth First! Zombies are the Solution!