Coal screenings

50 lb. bag
Recommended method of application: Drop spreader, or some Broadcast spreaders
Material: dusty, coarse powder
 
This is a natural, mined form of concentrated carbon.  This is a new product and as such, we would treat it as an experiment.  This will have many of the same benfits of other sources of carbon like humates and compost, but much cheaper (concentrated humates are extrated from forms of coal).  Use sparingly due to the possibility of some heavy metal contaminants, but levels should be low and not pose a risk (as with all dust, don't breath it).  
Apply up to a couple hundred pounds per acre.
Always check with your organic certifier before using any product.