Mosefund has one area with 30 small pigs - 75% Mangalitsa genetics.
They figured they'd be able to grow some pasture, then quickly rotate the pigs from pasture to pasture, allowing the plants to regrow. Bill Vingelen at the Herbfarm thought the same thing.
As pictures from Michael show, it is easy to underestimate the destructive capability of pigs. They don't just graze - they dig up the roots and eat them.
Mangalitsa pigs, according to the Iowa herdsman, are the "rootinest" pigs he's ever experienced. In his 40 years of working with pigs, he's never experienced ones that root so much.
Here's an untouched pasture:
Here is a pasture with the pigs on a little bit. Notice that they really destroy certain parts more than others:
Here's a pasture with the pigs on it less than 5 hours (adjacent is one they wiped out):
Here's a wiped out pasture. It tooks the pigs 24 hours to accomplish this:
One method to stop pigs from rooting is to ring them. Putting rings in their noses allows them to graze, but stops them from destroying things as much.
Although most iberico finish in pens, some of them spend 90 or so days running around outside, eating special feed. In order to stop them from destroying the environment, the get ringed. Here you can see a stock photo showing the process of ringing an iberico.
The ringing phenomenon illustrates something I've brought up before: when you run pigs indoors, there's no need to ring or spay them; when you want to do things outdoors, you either mutilate the pigs more or produce much less efficiently.