Here is a way to efficiently burn stumps:
1. Get a 55 gallon steel drum
2. Remove both the top and bottom
3. Cut some holes in the lower sides from ground level to about 1/3 the way up.
4. Place the barrel sleeve over a stump. Put a few crumpled-up paper sacks soaked in diesel fuel in the bottom and close to some of the holes. Pile all your wood debris in the barrel.
5. Light the sacks. [The barrel .sleeve contains the heat, creates a draft, and keeps the wood fuel from rolling off.]
6. Every couple of hours, poke into the holes with a metal rod to break up ash build-up.
Depending on the type of wood that you piled in and the size and type of stump, it may take between a couple hours to a couple days to burn the stump to below ground level. – P.S.