I'm not sure how much i should use. i started a soil mix about a year ago. original mix was sub's super soil. with lc's #2 mix on top,and to start in. after the first run,i reused the mix adding: 1 cup blood meal 1 cup bone meal 1 cup kelp meal 1 cup flower tone [epsoma] 1/2 cup bio starter [epsoma] all this was added to 3cuft of used soil mix. the mix sat for 2 months wet to effectively compost it[cook as some say]. every time the mix was used and returned to the tubs,it was refurbished this way. now i have found through the wonders of computers a place that sells bumper crop compost distributed through coast of maine. its time for a renewal of used soil and i have decided to use this Bumper Crop® Organic Soil Amendment i do not know how much to add per cubic foot of used soil. any recommendations? PS. thank you IN THE GARDEN for the help with the seedlings.there doing great and its time to transplant!