I don't know, but I'd say that it would depend a great deal on the conditions at the time of use. Warm and moist conditions would probably speed things up, just like it does in compost piles. I'm thinking that the presence of an abundant supply of active, healthy and hungry microbial life would factor in as well. So...mixing it with cold bare sand might take a significantly longer time than mixing it into a compost pile or an already amended and actively warm garden soil.
Can you elaborate on the question? Are you wanting to apply it directly to the base of plants, or plan to use it in containers, etc?
