I have a nearly unlimited supply of leaves and a shredder to make them fine..Now I want to make several compost piles. I know it takes both "brown" and "green" stuff to make compost. I also know that manure makes a good "green" stuff. What about the store bought bags of garden cow manure? Has it been treated in such a way as to make it useless for compost starting? During the summer months I will have enough curttngs etc to use, but I would like to get started while there is little else to do. Thanks for the hslp.