Troubleshooting Compost Odor Problems

Preventing and solving bad-smelling compost conditions

Composting can be a very enjoyable, rewarding practice, but if your bin or pile starts to produce unpleasant odors and smells, it becomes more of a nuisance than a joy. Your bin should not become odorous if you properly care for it, and rather than smelling rotten, it should smell like an earthly forest floor. So if you begin to notice smells like rotten eggs or ammonia emanating from your bin, assume that something is wrong with your compost conditions.

Ammonia odor

Generally speaking, if your bin smells like ammonia, it means that your compost has too much nitrogen, and that, in turn, means your compost pile contains too much of the green variety of material. Preventing your bin from high nitrogen levels is simple: simply ensure that you have an adequate balance of greens to browns in your bin.

But if you find yourself needing to counteract this compost odor problem, try the following solutions:

  • Add a 2-3 inch layer of dry brown material, such as newspaper, leaves (dry), or wood chips, to the top of your compost pile or bin.
  • Mix in a good portion of brown material throughout the compost pile or bin then give a handful of compost a squeeze test—if water beads between your fingers, the moisture level is perfect, but any more water is squeezed out, add more brown material to absorb some of the liquid.
  • You may also want to leave the lid of your bin off for a time to allow the material to dry out and get back into balance.

Rotten egg smell

When rotten egg smells become part of your composting experience, it means your pile or bin isn’t getting enough oxygen (it’s anaerobic) or that it’s too wet. These are common problems for newbie composters, but can also be faced by seasoned pros. Prevention is always preferred: Ensure a proper mix of raw materials, avoid wet raw materials as well as meat, dairy, and fats/grease, monitor compost temperatures, and give the contents a quick stir to add oxygen. You can also do a squeeze test to ensure you don’t have too much moisture each time you add more material to the bin or pile to test conditions.

Fixing rotten egg smells is just a matter of making a few adjustments to your compost composition. Here are some things you can try:

  • If your compost has become quite compacted, very little oxygen will be able to get in. Mixing in some bulky brown material such as shredded newspaper, wood chips, or dry leaves can add bulk and space for air to circulate more efficiently.
  • For outdoor bins, use a shovel or pitchfork to mix in some air to your compost material; for small indoor bins and vermicompost set-ups, use a handheld garden fork and gently turn the material once or twice, being careful not to injure your worms.
  • If your outdoor bin is exposed to rain, flooding, and other natural sources of water, then consider relocating it to an area where it will be protected against this excess moisture.

If you’re looking for a fast, no nonsense solution, you can also try an additive that will speed the process of decomposition while removing pathogens and other insects naturally. BiOWISH-Odor is one such option that uses microbes to assist with compost odor problems

  • Flies and larvae (fruit flies included): If you’re suffering from these, check your food-burying habits and ensure you’re covering scraps thoroughly. Then increase the temperature of your compost pile (to kill insect eggs) and make sure your moisture levels aren’t too high.
  • Fire ants: These pesky insects can be a challenge to obliterate, but they’re often a sign that your compost is too dry. Add water to your compost to correct the problem and then check back after a couple of days.
  • Rodents (rats, raccoons, etc): These critters are attracted to meats, fatty foods, and cooked foods, so make sure you’re excluding these from your bin or pile. If you’ve been adding egg shells, be sure you’re rinsing and crushing them beforehand to eliminate odors they may cause. Then check to see whether there are spaces through which a rodent could get into your bin—underneath, through bin doors, or through the. If so, consider adding a secure-fitting lid and wire mesh to open sides and the floor of your compost bin (if it’s just resting on the ground). You can also line the sides of your bin with rocks or bricks to prevent rodents from borrowing in. Alternatively, consider purchasing rodent-proof bins that are already fitted with such deterrents. 


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