"After nine years, corn yields were similar in the standard no-tillage and cover crop systems but were 12% lower in the crownvetch system and 28% lower in the organic farming system than in the standard no-tillage system."The shockingly poor yield of organic grain here was due to a massive proliferation of weeds - which are extremely difficult to control without herbicide.
They also measured yield of corn that was grown conventionally on fields that had been in either conventional or organic production for the previous 9 years. Conventionally-grown corn yields were 18% higher when grown on fields that were historically managed organically.Organic management (in this system) really improved the soil - mostly through increased nitrogen levels, probably. The catch though is that the organic fields were overwhelmed with weeds!
Sounds like a good opportunity to combine the best of both approaches.