Composting Series: Food Safety Issues Related to Compost

Juan Fernando Moreira Calix, Dunaway, Christopher R., Kuehny, Jeff S., Adhikari, Achyut, Timmerman, Anna, Hammett, Bert, Willis, Joe


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Foodborne pathogens are microorganisms that can adversely affect a person’s health when ingested. These pathogens can be found in many diverse environments in our everyday life. Environments in which pathogens can survive and multiply are known as reservoirs. Animals are an example of reservoirs because pathogens may live in their skin, digestive tracts and manure. Considering that animal manure is an important material in certain composts, and these are used for growing produce, it is important to be aware of ways to reduce food safety risks related to their application.


Treated vs. Untreated:

Compost that is “treated” refers to a compost to which a scientifically validated procedure has been applied in order to reduce pathogens present in the compost. This treatment process usually refers to using heat to reduce pathogens; however, as long as the process has been scientifically proven to be effective in reducing pathogens, heat may not be necessary. Any compost that has not undergone a validated process is considered “untreated.” Untreated compost will have a higher likelihood of being a reservoir for pathogens, and, therefore, a higher likelihood of transferring those pathogens to our crops.

Applying Compost to Crops:

When deciding what composting technique may be the best fit for you, it is always important to consider what compost presents a higher food safety risk to you. When using an untreated compost, one must always try to avoid this type of compost from coming in contact with the edible parts of our crops. The U.S. Department of Agriculture’s National Organic Program recommends that if a compost is untreated and is not tilled into the soil, then the crop should be harvested 120 days after application. If the compost being used is untreated and is tilled into the soil, then the crop should be harvested 90 days after application. However, if the compost being used is treated, then there is no interval needed before harvesting.

Considerations When Using Compost:

  • Always keep treated composts separate from untreated composts.
  • If using untreated composts, do not use the harvesting space again for a couple months.
  • Tools used for untreated composts should only be used for untreated composts.
  • Always keep children and pets away from untreated composts.
  • When deciding if use of untreated composts is appropriate, consider using them for crops that later need to be cooked.
  • Can attract fruit flies
  • Effectively reduces pathogens.


Juan Moreira, Research Assistant, School of Nutrition and Food Sciences; Achyut Adhikari, Associate Professor, School of Nutrition and Food Sciences; Christopher Dunaway, Assistant Extension Agent, Jefferson Parish; Bert Hammett, Extension Agent, East Baton Rouge Parish; Jeff Kuehny, Director, LSU AgCenter Botanic Gardens; Anna Timmerman, Assistant Extension Agent, St. Bernard Parish and Joe Willis, Extension Agent, Orleans Parish.

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Pub. 3838-G (Online Only) 04/22

Luke Laborde, Interim LSU Vice President for Agriculture

Louisiana State University Agricultural Center, Louisiana Agricultural Experiment Station, Louisiana Cooperative Extension Service, LSU College of Agriculture

The LSU AgCenter and LSU provide equal opportunities in programs and employment.

Funding for this publication is provide by the USDA NIFA FSOP Award #: 2020‐70020‐33035

4/27/2022 4:38:48 PM
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