#1; Exposure to Pathogens
Fresh manure has microbes in it that may be dangerous. It should be incorporated into the soil only when it is aged or composted. Do not apply fresh manure to edible crops that will soon be harvested or store manure next to produce storage or handling areas.
If manure touches foods, it can cause foodborne illnesses, notes the University of Florida. If it is stored rather than incorporated into the soil, make sure there is no runoff into sources of drinking water or food production areas. Wheelbarrows, buckets, and equipment that have touched fresh manure should not touch produce that will be eaten raw.
The amount of nitrogen in manure depends on the type of animal, how they are fed, the amount of bedding mixed with the manure, and the storage and collection methods. Controlling application rates is difficult to impossible with manure, but in most cases, the nutrients are released slowly enough that it does not cause problems. If large amounts of fresh poultry manure are applied to already fertile soil, there may be enough nitrogen to damage the roots of young plants.