Biosphere 2: farming while sealed off from the world

Mark Nelson is an environmental engineer, author, and farmer at Synergia Ranch, in Santa Fe, NM. He's co-author of the book, Life Under Glass : Crucial lessons in planetary stewardship from Biosphere 2, and he's in a new documentary about Biosphere 2, Spaceship Earth.
Starrlight Augustine is a scientist manager of the organic farm at Synergia Ranch. We talk about the experience and lessons of Biosphere 2, and their methods of farming in New Mexico.