Pulverizing charcoal into small pieces and dust creates higher amounts of surface area, maximizing the charcoal’s effectiveness in the soil. In order to pulverize, make sure the charcoal is wet, as the dust can be harmful to your lungs. Place the charred coal on a tarp and crush, for example by driving a tractor or car over it.
It is possible to incorporate any desired fertilizer at this point to soak into the biochar, which is also called "charging" the charcoal. These fertilizers should include nitrogen, phosphorus, and ideally active biological activity, such as found in composted manures. Dry fertilizers, such as pelleted chicken manure, can be added during her pulverizing process. You will want to wet the charcoal while charging, but do not put it in standing water, as access to oxygen is key to keeping the biological activity alive.
Additional methods for charging biochar is to use it as bedding material for animals or to add it to compost piles. Raw charcoal, without adding nutrients, can absorb fertility from your soil and provide ill effects in the first year.