“There are food safety issues arising from the use of manure in that animal feces contain high levels of human pathogenic organisms which can be transferred to crops on which it is used. Aged or properly composed manure tends to reduce the risk from the use of animal waste materials. However, it is important that all farms using manure follow good agricultural practices to reduce any microbial risk that may exist. These include:

  • Consider the source, storage, and type of manure.
  • Store manure as far away as practical from areas where fresh produce is being grown and handled. If manure is not composted, age the manure at least six months prior to field application.
  • Where possible, erect physical barriers or wind barriers to prevent runoff and wind drift of manure particles.
  • Store manure slurry for at least 60 days in the summer and 90 days in the winter before applying to fields.
  • Compost manure using proper temperature and turning techniques.
  • Plan manure application in a timely and careful manner.
  • Apply manure in the fall or at the end of the season to all planned vegetable fields, preferably when soils are warm, non-saturated, and cover-cropped.
  • Use only properly decomposed manure on crops like lettuce and leafy greens.
  • Avoid planting root or leafy crops in the year that manure is applied to a field.
  • Incorporate manure into the soil.
  • Do not harvest vegetables until 120 days after manure (is applied) if possible.
  • Document rates, dates and locations of manure applications.

After-harvest sanitation is also critical. Hygiene is the basis for good practices and proper hand washing is the key. “Wash hands for at least 20 seconds before beginning work with produce,” Masabni said.

He also recommends checking worker health daily. “A big percentage of contamination comes from sick workers.”

Watching for foodborne illnesses in employees is also important to assure their safety. Masabni said symptoms to look for include loss of consciousness, nausea, sweating or fever and abdominal cramps.

“Educate employees about good agricultural practices,” he said. “The Extension Service offers GAP training.

“But prevention is the key and proper hand washing is the best method to reduce potential for contamination. And make certain to prevent raw manure contamination.”