Dan, the only qualification that I would add is that cow manure isn't so benign, at least fresh manure, as there have been many cases of ecoli contamination of foods stemming from fresh cow manure. All fecal matter has to be managed appropriately and with deference. According to composting experts, they claim that composted material has greater fertility. Also, a compost pile is the perfect place to incorporate and innoculate biochar, bringing the discussion back to charcoal.
I favour more biochar, and more nutrient recycling.