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Why You Have Smelly Compost & How to Fix It

Posted November 11, 2022

Do you find your compost bin smells bad? As surprising as it may sound, composting done right should result in an earthy aroma, not an offensive stench.

Why Is My Compost Smelly?

Composting is a balancing act between organic materials and proper ventilation. If this balance is disrupted, or there’s inadequate oxygen, the bin’s contents will rot instead of decomposing properly, leading to a foul smell. Fortunately, there are practical ways to remedy this.

Understanding Ammonia Odor from Your Compost

Successful composting requires the correct mix of brown (carbon) and green (nitrogen) materials. For the GEOBIN® Composter, we advise a 3:1 ratio of browns to greens. Carbon sources can be dried leaves, twigs, cardboard, and sawdust, while green materials include food scraps, grass clippings, and coffee grounds.

If you detect an ammonia smell from your compost bin, it’s likely due to too much green material. Rectify this by adding more carbon-rich material, which acts as the energy source for your compost.

Why Does Your Compost Smell Like Rotten Eggs or Garbage?

layers in GEOBIN composter
<em>Figure 1<em>

The reasons for this can be:

  1. Oxygen shortage due to compaction: Composting needs oxygen. If your pile becomes too compacted, airflow decreases. To fix this, mix the pile and add airy material like dried leaves.
  2. Excess moisture: This is common in rainy seasons when your compost may become too wet, lacking necessary aeration and causing a rotten smell. Adding more brown material can absorb the extra moisture and help fix the smell.
  3. Incorrect layering: If green material gets separated from brown material, it begins to rot, emitting a bad smell. Mixing up your pile can help. See Figure 1.
  4. Wrong additions to the compost: Meat, fat, or dairy items emit unpleasant odors during decomposition and can attract pests. It’s best to avoid these.


Beyond reacting to problems, regular maintenance of your compost pile can proactively prevent unpleasant odors. Turning your compost pile weekly helps maintain a good oxygen level and promotes even decomposition. Regularly checking the moisture level is also essential. If it feels too dry, adding water or more green materials can help. If it’s too wet, introduce more brown materials to balance the moisture


While the process of composting might seem challenging initially, it soon becomes an effortless and rewarding habit. With time, you’ll learn to identify what your compost needs just by observing it. You’ll be able to tell if it’s too dry or too wet, or if it needs more green or brown materials. In return, your compost will provide nutrient-rich material that helps your garden thrive while contributing to a more sustainable planet. Remember, a well-managed compost pile is not just an asset to your garden, but it’s also a vital tool in waste management and reducing landfill contribution.