While it’s possible for a stump to rot and decompose naturally, it may take months if not years. And in some cases, shoots may sprout up in an attempt to regrow the tree.
Cutting into the stump and covering it in compost or soil will help speed up the process, but problems can still remain. Honey fungus can begin to grow on dead rotting wood, which tends to spread and infest other live foliage.
Grinding the stump until you’ve reached 4 inches or more into the ground, then covering it in compost and top soil will be your best option.
This will help to ensure no shoots spout up and no sunlight can reach the remaining stump to grow fungus.