This is an excerpt from "Food Safety News - Take care to avoid risk with backyard chickens" dated 6-13-11
Brad Henderson said there is some risk of pathogen contamination if fresh chicken manure is put directly on food gardens. However, if given enough sun, heat and time, chicken manure that goes through the composting process will be stripped of any harmful bacteria. Chicken manure should be cured for 45-60 days before adding it to a vegetable bed, according to a
report compiled by Judy Duncan, King County Master Gardener and WSU Cooperative Extension livestock advisor (
http://seattletilth.org/learn/resources-1/city-chickens/compostingchickenmanure). During the curing process, no more chicken manure should be added. Since chicken manure is so nitrogen-rich, the compost heats up more quickly, killing any harmful bacteria in a shorter amount of time than most other types of manures, said Sheri Hinshaw, environmental educator for the Seattle Tilth Garden Hotline.
“When you add compost to your garden it should be dark, crumbly, and sweet-smelling,” Hinshaw said. “But Salmonella is very rare in composted chicken manure.”
According to Duncan’s report, fresh chicken manure has the highest chance of contaminating crops such as carrots, radishes, beets, lettuce and spinach. However, appropriately composting the manure should kill any potentially harmful bacteria. A compost temperature gauge can be purchased to see if the compost is between 130-150 degrees Fahrenheit, which is the temperature required to kill harmful bacteria. However, if a temperature gauge isn’t handy, then letting the compost cure for 45-60 days will do the trick.
People who are especially at risk if exposed to Salmonella should avoid eating uncooked vegetables from gardens that use any type of manure. These at-risk groups include pregnant women, young children, and people with chronic diseases. Chicken manure can also be used without risk of food-contamination by adding it to a flower garden instead.