A paper has been published on “​Environmental Drivers for Persistence of Escherichia coli and Salmonella in Manure-Amended Soils: A Meta-Analysis” by Dao Tran and colleagues at the ARC Training Centre for Food Safety in the Fresh Produce Industry.

The paper, which appeared in the Journal of Food Protection in July, examines 42 primary research studies on pathogen persistence from manure-amended soils, and concludes that “Based on the significant variation observed among individual field studies, it is unlikely the risks associated with the use of manure amendments containing high levels of enteric bacterial pathogens (such as in raw manure) in soils may be solely managed by a uniform exclusion period. Management of the risks associated with the use of soils amended with raw manures is best achieved through risk-based approaches incorporating differences in climate, soil management, and initial levels of bacteria during application.”

While it is recommended that only certified composted organic amendments are used in the production of fresh produce, the message is clear: risk-based approaches taking into account local environmental factors must be used by growers for determining appropriate exclusion periods after using untreated manures. More here.