Horseshit. Nitrogen is nitrogen. The plants don't care. Only the hippy growers do. I say this as a largely organic grower. The downside of using chemical based ferilizers is that they can easily burn your plants, and a poorly designed nute will build up in the soil. However, apply too much chicken manure, and you'll get the same effect. Properly applied, chemical ferts are indistinguisable by the plant from organic ferts. Anyone who says otherwise needs to read up on basic chemistry. There is no such thing as 'organic' nitrogen.