Whatever you think of Eliot Coleman, this really is a great article, and well worth taking the time to read
Organic agriculture: deeply rooted in science and ecology (by Eliot Coleman – Grist)
EXCERPT: Skeptics have often misrepresented a biologically-based agriculture as if it is nothing but the substitution of purchased organic inputs for purchased chemical inputs. Even if there were evidence to document the rationale for a substitution philosophy, it would lose on the grounds of economics alone. Both bone meal and dried blood, for example, two popular “organic” fertilizers, are prohibitively expensive on a farm scale. Furthermore, such substitution thinking is not pertinent to the actual objective of a biological agriculture — namely the development of sustainable, farm-generated systems for maintaining soil fertility.
Hope you’ll read it and send in your comments.