Author: Jeanette Thurston-Enriquez, USDA Agricultural Research Service scientist, jthurston2@unl.edu
Proper handling and composting of manure will help to eliminate most pathogens. Some of the factors that reduce the survival of pathogens are:
• High temperatures: Each pathogen has a different susceptibility, but generally high temperatures are very effective in reducing populations.
• Time: Bacteria are living organisms, so they can't live forever. If manure is land applied at a time when you know you will not have a runoff event and a pathogen has time to end its life cycle before a runoff event can occur, that will reduce the pathogens found in agricultural environments.
• Sunlight: Sunlight has a couple of effects on pathogens. It desiccates (reduces moisture) them, and the UV light also inactivates pathogens. This second factor is relatively low in importance for manure-laden soils as pathogens are encapsulated in manure materials and are mostly protected from sunlight.
• Desiccation: This is one of the best ways to inactivate pathogens and reduce them in the environment.
In addition to decreasing the survival of pathogens, it is also important to minimize the possibility of pathogens being transported into the environment. Transport of pathogens to streams and groundwater generally occurs due to water and soil transport from fields that receive manure applications and from improper manure-handling practices. To minimize microbial transport, avoid overapplications, and do not apply manure on wet or frozen fields and for several days before predicted rainfall. If pathogens have reached streams and/or groundwater, they can survive longer than in fields and soils, especially during the winter and spring when water is cooler than during the summer.
