(This article by Phillip Tocco of Michigan State University Extension was first published here on March 4, 2015, and is reposted with permission.) Manure can be a significant benefit to growing fresh produce or a potential threat to food safety when applied on produce farms. Raw manure should never come into contact with harvested produce, and, in all cases, produce in the field. Proper application and storage of manure near produce farms is essential to ensure a reduced risk of contamination. Improper application can result in costly recalls or worse. In general, manure should be stored at least 100 yards from the produce-growing area. Care should be taken to make sure that no runoff from the storage facility enters the production area. If you choose to periodically check the manure storage area to ensure this, it should be written as part of a Standard Operating Procedure and the periodic monitoring should be recorded on a manure storage log sheet. Either an annual calibration of the application equipment to ensure an effective rate of nutrient application, or a manure nutrient test with applications in each field in tons per acre, can serve to validate your rate of application based on crop removal. In either case, include any documentation or record the date of calibration in your Food Safety Manual. It is also important to be aware of what some food safety auditors may consider to be raw manure. In some cases, food safety auditors have considered fish emulsion to be raw manure. If using fish emulsion, be sure you have documented assurance from the supplier that it contains no detectable generic E. coli. This documented assurance should be in the form of an analysis report. As an additional precaution, Michigan State University Extension recommends delivering the fish emulsion through a drip line or other means where there is no direct contact of the fish emulsion with the edible portion of the plant. If you have specific questions about manure use or have difficulty tailoring GAPs to your farm, contact the Agrifood Safety Work Group at gaps@msu.edu or (517) 788-4292.

  • MaryFinelli

    A much better practice is to instead employ green (i.e., vegetative) “manure.”

  • Food Microbiologist

    All manure should be properly composted to inactivate zoonoses. Salmonellae and STECs can survive in soil and either end up on vegetables via splash or via the plant’s vascular system.

  • Sansher

    we only have to remember the Posey Melon Outbreak to see how entities deal with manure applications on produce. In this case canteloupes were in the field when manure was applied and were sold without any wash. Sale logs were not kept, stickers were not used on the produce, making traceback difficult. Although this occurred in Indiana, in the questions surrounding it, we discover that A. produce in Indiana and Michigan is harvested without using a Packing House. B. that although sale logs are suggested, when they are not used, no penalties are imposed. C. Farmers do not work with regulators, in fact just the opposite. This is in direct opposition to Florida and California where regulators and farmers work together. In the case of Ca and Fl. farmers want to be regulated because their produce is sold internationally and being regulated State wide and using Packing Houses are things that clients overseas prefer. Michigan uses the “local rule” mantra with a weak central government (Lansing). Every township and village makes its own rules and pays for their own enforcement. They might ship across state lines but do not sell internationally. Ive worked in food safety in Michigan and in Florida, if I see a cantaloupe with a Florida sticker, and one with a Michigan sticker, which one do you think Im going to choose?

    • pawpaw

      We refuse to eat most cantaloupe, with so much surface area on its rough rind. Unless we grow it or know well the farmer and the farm who did. Certain foods simply have a higher risk of retaining contaminants anywhere along the path from farm to fork, and this rough-skinned fruit is one of them.

  • Alex Dubois

    There is another alternative. Rather than use raw swine manure, which can be a little difficult to control, use processed poultry manure, such as products from Mighty Grow Organics. The fertilizer is uniform in shape, low to no odor, pathogen free, and enhanced with added trace minerals and beneficial microbes. It is OMRI listed and can be used WITHOUT restrictions. Just a thought.

  • AnnaFiona

    The vast majority of fbi is due to this, as the saying goes “spinach does not poop.” Our food is being contaminated by “ingenious” ways these farmers are using animal waste. There is so much of it, they are running out of disposal space/function. Yes, vegetative manure is safe, and I have read many articles of it’s success in growth/health of products. However, the utilization of this method would depend upon logic and care, rather than bottom line/greed, I cannot see the farming industry taking that route.

    • Sansher

      Like I said in my comments, there is the gamut between farmers cooperating with regulators and farmers not cooperating. There are a lot of farmers that don’t have greed as the bottom line, they truly enjoy what they do, and that’s why they do it. I’ve worked as a regulator, with some farmers in the Migrant Labor program in Fla and also in the well programs there, Overall, they were a good lot.