Sepp Holzer uses pigs to "waterproof" his ponds. They roam around and eventually compress the earth. And he famously said, if you don't have pigs, you will have

Sepp Holzer uses pigs to "waterproof" his ponds. They roam around and eventually compress the earth. And he famously said, if you don't have pigs, you will have to do the pigs' work!