Maybe Bruneti 's comments are applicable only to commercial farmlands. The woods outside my door are full of edible plants, and the area has never been farmed. I've never taken a deer, rabbitt or squirrel here that I noticed to have a goiter, and they all have thyroids. My read is that the soils have enough Iodine to keep all the critters healthy, including me. When the grocery stores close and all the human apes are clobbering one another over a can of pinto beans, I'll be in the woods getting my fill. Just don't eat the monkshood, irises, and a few others. There are so many edible plants and roots out there, existing in places that have never been farmed, where the soil is as pristine now as it was 1000 years ago, that it ain't even funny. Soil depletion only applies to those whose knowledge of edible foodstuffs has been limited by their "edgemacation"