Why does my compost tea smell bad?
Written by
Kiana Okafor
Reviewed by
Prof. Samuel Fitzgerald, Ph.D.The presence of foul odors during the brewing of compost tea indicates potential severe microbial imbalances, suggesting that immediate action is needed. Foul odors are indicative of 1) contamination with anaerobic conditions, 2) problems with the ingredients used. I have salvaged several batches of compost tea once I recognized the odors early on. Being aware of these indicators can prevent plant injury and save time from having to restart batches. Being able to diagnose an issue properly enables swift corrective actions.
Sulfur/Rotten Egg
- Indicates anaerobic bacterial dominance
- Caused by insufficient oxygen or overpopulation
- Requires immediate ascorbic acid addition
- Discard if smell persists after treatment
Ammonia
- Signals immature compost with excess nitrogen
- Results from unfinished decomposition processes
- Strain tea and replace compost source
- Test new compost before reuse
Putrid/Decaying
- Reveals pathogen contamination
- Often from animal manure or contaminated water
- Discard entire batch immediately
- Sterilize all equipment before restarting
Minimizing odors can be achieved by selecting suitable ingredients and maintaining optimal brewing conditions. Use only mature compost that has an earthy smell. Maintain temperatures between 55-80°F. I check the temperature using floating thermometers. Good aeration is ensured by checking the pump every hour. For brews that are not aerated, stir every 4-6 hours.
Use recovery protocols as soon as a problem is noticed. Use ascorbic acid for sulfur smells and to increase air flow. Strain and replace the compost to eliminate the smell of ammonia. I always keep emergency supplies on hand during a critical brewing window. Never use smelly tea on plants, as it can endanger the roots.
Safety protocols will keep you safe during troubleshooting. Use nitrile gloves and an N95 mask when handling contaminated brews. Work in a ventilated location that is away from your personal living areas. I even wear eye protection regularly when doing corrective action. Position problem batches separately before disposing of waste.
Read the full article: Compost Tea Brewing: The Ultimate Guide
