I don't know ED.
  We have tried about everything under the sun to get high yield beans. Just never make it over the hump..  Don't even know if o we are above average. Yields haven't improved much from when we used conventional tillage with the MF drill to the oliver drill with a pull rope to new great plains no-till drill,then on to 750 drill and now a new kinze 15 inch planter last year. From full till to no-till. Bean seeds from the older non-gmo save your own to the latest and greatest RR'2 's. Treated and non treated. From spreading fertilizer spring or fall with AMS with out . lime by the truckloads. Spraying insecticides and fungicides...You name we have tried it.
  Beginning to think it's not high yield beans but high yield farmers.I guess you know what category we fit.