I have to disagree here. When we are looking at increasing SOM, bulk is king. Compare the cost of any other organic based product you can find on the market, buy it in bulk, compost it and measure your end quantity, then see where you come out financially in comparison to a comparable amount of compost. Around these parts, Feather meal costs $35/50 lbs before shipping and tax, CGM at $60/65 lbs as opposed to $35/yard for high quality compost. If I need 2 acre-inches of stable organic matter (C:N of ~13-15) to bring my SOM to an acceptable value (5-10%), I think it is pretty clear which one of the three will be the most cost effective and marketable.