By Jennifer Copley (Last Updated 8 March 2011)
When compost contains a proper balance of materials and receives sufficient aeration, it does not produce strong, unpleasant smells. When there is an imbalance or lack of air circulation, compost may reek of rotten eggs or ammonia, depending on the problem.
Why does my compost smell like rotten eggs?
A rotten-egg smell indicates that the compost is not getting sufficient air. Stir or turn the pile to aerate it and break clumps apart. Then add a thin layer of soil on top. Adding some dry, carbon-rich material (such as straw or dried leaves or grass) can help to keep the pile drier and more aerated.
Why does my compost smell like ammonia?
This occurs when compost has too much nitrogen-rich or “green” material (kitchen scraps, wet grass, etc.) and not enough carbon-rich material. In this case the pile will likely be soggy and muddy. Add some carbon-rich material such as dry leaves, turn the pile over, and add a thin layer of soil on top.