QUESTION: How bad does a compost bin smell? I want to start composting in our back yard, but my husband says it will stink. – Leah H
ANSWER: A healthy compost pile should smell like earth—not a putrid, rotting, or otherwise disagreeable scent. However, compost that is out of balance can develop an odor that indicates a problem. How you should go about troubleshooting a stinky compost heap depends on the type of smell it is producing.
If your compost begins to smell like ammonia, it contains too much wet material that is full of nitrogen (“green” ingredients). The ammonia smell can be corrected by drying the compost out and adding more “brown” ingredients rich in carbon to correct the balance.
You can start by leaving the lid off of your compost container on a warm, sunny day. If the compost inside is still too damp, you may need to remove it from its container and spread it out so that it dries more quickly and easily. When you return your compost to its usual spot, mix in some carbon-heavy materials. Dried leaves are a good go-to for adding carbon to your compost, but if they aren’t available to you, you can use shredded newspaper or cardboard instead.
On the other hand, if your compost develops a sulfuric odor similar to a rotten egg, the stink is alerting you to one of a few problems. First, this kind of smell can result from including meat, grease, dairy, or fish in your compost. If you’ve been adding these materials to your compost heap, you should stop doing so immediately. In addition to causing an unpleasant smell, these ingredients can also attract pests.
A sulfuric aroma can also indicate that your compost needs oxygen, resulting in a surplus of anaerobic microbes. This problem is easy enough to resolve by mixing the compost with a pitchfork or compost turner, and perhaps adding air holes to the bottom or sides of your container if needed. Adding more “brown” carbon-heavy materials such as dried leaves can also help absorb any excess moisture and loosen the pile so air can circulate more freely. If you don’t have access to dried leaves, you can use shredded newspaper or cardboard to add some carbon to your compost in a pinch.