Carbon-to-nitrogen ratio

The carbon-to-nitrogen ratio, written C:N, tells you how much carbon a material has for each part of nitrogen. A high number means a lot of carbon and little nitrogen. Wood is high.

Purdue Extension says the woody debris created from stump grinding has a high carbon to nitrogen ratio, and this reduces nitrogen availability for the new tree or grass. Microbes that rot the wood take nitrogen from the soil around it. This effect is called nitrogen tie-up.

Purdue advises adding slow-release turf fertilizer to make up for it. Removing the stump grindings and adding topsoil lowers the problem at its source. See can you plant grass after stump grinding.