To enhance decay conditions, the stump should be cut as near ground level as possible, covered with sod and kept moist. If possible, several large holes at least 1 inch in diameter should be bored vertically into the stump. These holes expose more wood and slightly hasten decay. During the first year following tree removal, the organisms that decay the wood tend to be nitrogen-limited. That means that the addition of fertilizer during the first year, especially a high nitrogen fertilizer, will hasten decay. Be careful not to add so much as to cause a fertilizer “burn” to surrounding plants.
The organisms that come along to decay the stump after the first year or so tend to be carbon-limited. That means that adding high nitrogen fertilizer no longer hastens the decay. The alternative is to add carbons (in the form of sugar) to the wood after the first year. Simply add some ordinary granulated sugar through those holes and the process will speed up considerably. Keep in mind that the heartwood of some species such as cedar, mulberry, bois d’arc and locust are naturally durable and will take much longer to decay than softer woods.