Science and Engineering

Monitoring Compost Odors

A well-constructed compost system should not produce offensive odors, although it will not be odor-free. You can use your nose to detect potential problems as your composting progresses. For example, if you notice an ammonia odor, your mix probably is too rich in nitrogen (the C/N ratio is too low), and you should mix in a carbon source such as leaves or wood shavings. If you smell a musty odor, it may be because the mix is too moist, which you can correct by adding more of your bulking agent. Left uncorrected, compost that is too wet may go anaerobic, producing a foul sulfurous odor that is hard to ignore. If this occurs in indoor bioreactors, you may wish to take them outside or vent them to the outside, then aerate or mix thoroughly and add additional absorbant material such as wood chips or sawdust. In an outdoor compost pile, turning the pile may be sufficent to correct the anaerobic condition, although initially this may make the odor even more pronounced.

For more information on the science of compost odors and the engineering of compost systems to minimize odor problems go to Odor Management.


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