 In terms of the barn system, you can manage your manures. It's very difficult to manage your manures in a free-range system. So I've seen this with the barns I go into, and the farmer just comes in with a bulldozer, scrapes out the manure. Free-range chickens, of which I have five in my garden, the idea of picking up even the smallest amounts of chicken poo from my tiny lawn would be impossible. Yeah, it's a lot. And there is a lot of phosphorus in chicken poo.