How to make biochar from bags of lump charcoal

Описание: I don't want to make my own charcoal to use as a biochar in my garden. I live in the city and don't really have a good spot to make charcoal here or a good source of input material. I bought some bags of lump charcoal from the home center instead. This bag of charcoal is all hardwood and contains no additives, so it will be suitable for application in the garden.