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Canada: Verifying Safety of Compost Used for Vegetable Production

Figure 2. E. coli and fecal coliform measurements in market ready composts in British Columbia after rewetting and incubation for 24-48 hours.

The future of our organic vegetable industry, as well as the future of our organics recycling industry relies on us all participating to ensure the safety of our produce.

By John Paul, PhD PAg
Transform Compost
Jan 30, 2018


What can we do to provide assurance that potential pathogens from compost do not enter the food chain? There is evidence identifying the risk of potential pathogen regrowth, including E. coli, particularly with immature compost. Researchers have identified potential human pathogenic organisms that can enter a VNBC (Viable but not Culturable) state, including antibiotic resistant E. coli, which allows them to survive the high temperatures required for the composting process.

In a review of the OMRI Listed (OMRI Canada) residential food waste and yard waste compost produced by the City of Whitehorse, we conducted further testing to ensure that potential pathogens would not regrow. Compost samples were taken from various stages in the aerated windrow composting process, stored at 5-15 C for 48 hours, then sent to the laboratory to measure fecal coliform and maturity. We found that compost that met the CCME maturity requirement (< 4 mg CO2-C/g OM/day) still had risk of fecal coliform regrowth, and there was no regrowth in compost having a respiration rate below 1.5 CO2-C/g OM/day). The OMRI approved compost marketed by the City of Whitehorse was determined to be safe with no potential for potential pathogen regrowth.

See full paper by following the link below.

Compost Safety Verification Jan 30 2018