You can kill tree stumps with a variety of methods, both nontoxic and chemically based. Some methods require more labour while other methods only require a treatment and waiting for the product to work automatically. All methods may require repeated treatments to completely kill and remove the stumps.
Stump remover chemicals, usually made of powdered potassium nitrate, decompose tree stumps over a four- to six-week period. Most products require you to drill a series of holes in the stump. Pour the chemical into each hole and wait for the stump to decompose. When it does, the stump will turn into a spongy textured wood you can break apart with an axe.
If your city is not under a burn ordinance and you have some scrap wood to burn you can use fire to kill the tree stump. Collect a pile of wood pieces on top of the stump. Add some smaller sticks into the wood pieces before starting the fire to help the fire start and heat up the bigger wood pieces. Place additional pieces of wood on the fire as needed until the fire burns through the stump.
If you dislodge and break apart the tree roots, it will kill and remove the tree stump all at once. Use a shovel to dig around the tree and expose the roots. Grab an axe next to break up and sever the roots. If the axe isn't strong enough, cut tough roots with a pruning saw or root saw. Grab and pull the roots out of the ground; use a grub hoe to dislodge large roots and stump pieces.
Warnings and Suggestions
If you sever the tree's roots, you can let the stump decay naturally. It may take as long as 10 years to completely decay. If burning the stump, enclose it in chicken wire and watch it closely. Keep pets and children away from the stump if you choose to burn it or apply chemical products.