Op-Ed Contributor - Yellow Is the New Green - NYTimes.com

Human and animal waste are vastly underused sources of nutrients for agricultural production. Yet globally prices of fertilizers, nitrogen and phosphorus in particular, have been skyrocketting. Phosphorus supplies are finite, and we'll soon start hitting the wall with our phosphorus supplies. The sooner we start figuring out how to recycle wastes on a large scale for use in agriculture, both human and animal wastes, the better.