In a personal communication, Prof. John Reganold told me (perso comm) that for a comparative trial between organic and Biodynamic to be scientific you need four blocks that are 50% organic and 50% Biodynamic. All management practices such as cover crop selections, seeding rates, ploughing times, use of suffur and copper-based sprays (eg Bordeaux mixture) are identical except that one plot gets the Biodynamic preparations and one does not. This means more work, at least until the system is up and running. It will mean, for instance, making two composts that are identical, but one has the Biodynamic compost preparations in and the other does not. The Biodynamic half of the vine block gets all nine Biodynamic preparations (Horn Manure 500, Horn Silica 501 and Horsetail 508 plus the six preparations preps via the compost) while the other “organic by default” gets no preparation sprays and no compost preparations.”