Composting Poultry Manure to Reduce the Spread of Pathogens

It is once again the time of year when the poultry industry tends to see an increase in respiratory disease. Winter conditions also make these diseases more challenging to overcome. Ventilation rates can be tricky to manage, and sudden temperature or environmental changes can cause stress that weakens immune responses. Damp and cold conditions increase pathogen survival times or make high humidity, wet litter, and higher ammonia levels more commonplace, leading to increased susceptibility to certain diseases and a more favorable environment for secondary bacterial infections.

Although overall management is crucial for producers impacted by these diseases, so are practices following a disease challenge, especially if there are other poultry farms nearby. Proper handling of manure or litter from an infected flock can help protect the greater industry. In a state with several very poultry-dense regions, these practices can be the difference in stopping the spread of disease to other operations.

Composting is a good option for handling manure or litter following a disease challenge. Many producers spread manure on fields, but this can pose a risk of disease spread to nearby poultry operations after an outbreak. Proper composting before spreading can inactivate any pathogens present. Composting inside the barn may also help raise the barn's overall temperature and assist in inactivating pathogens elsewhere in the environment.

The basic components necessary for functional compost include a carbon source (mulch, shavings, etc.), a nitrogen source (manure in this case), water or moisture, and finally oxygen. The exact amounts will vary depending on the housing and bird type, as well as the condition of the manure or litter. To reach optimal temperatures for pathogen activation and break down the manure, most farms will need to bring in additional carbon. The materials must be mixed well enough so that the microbes that aid in the process can access all the necessary components at once (carbon, nitrogen, water, oxygen). Carbon-to-nitrogen ratios are commonly cited but can be tough to determine without extensive testing. However, a 5:1 ratio of ground mulch to poultry manure is common for just manure without added carbon in the form of litter or bedding material.

Moisture of the mixed material should be 40-60%. Additional water may be necessary, depending on the consistency of the mixed materials. Lastly, for proper airflow, the texture of the carbon sources is important. Coarser materials can help create air pockets and facilitate air flow through the pile. Poultry manure on its own, or that has been compacted with litter over many flocks, is quite dense and may need a coarse or single-ground mulch as an additional carbon source to keep it from clumping up and blocking air flow.

The shape of the compost pile is as important as the materials used in its construction. Composting windows can be as long as necessary, but should have a wider base tapering into a narrower top. Generally, they should be about twice as wide at the base as they are in height. For example, a 6-foot-tall windrow should have a base that is about 12 feet wide. Large, round piles (as opposed to long, narrow ones) are less effective because airflow is less likely to reach the center.

After the piles are built, taking temperatures will help determine if the compost is active. The timeframe the compost is left is less important than the temperature that it reaches, especially when attempting to eliminate pathogens. Temperature requirements may vary depending on the disease, but 131°F for 3 days in a row is a good rule of thumb. Keep in mind, reaching this temperature does not mean the manure is completely decomposed yet. The temperature of compost will usually reach a peak, which may be slightly higher than this, and then start to come back down. This is a good indicator that it is time to "turn" the pile, a process in which the material is thoroughly mixed and reshaped. Turning can boost microbial activity by adding air to the pile and breaking up compacted areas. Temperatures should then follow a similar pattern during this second cycle.

Extended downtimes will help avoid reinfection in your own flock and protect your neighbors, in addition to composting. However, if extended downtime is not possible in your scenario, it is recommended to heat the house to 100°F for 72–100 hours, followed by windrowing the litter in-house for 3 days in a partial composting cycle. Though a full composting cycle is preferred (times will vary; temperatures are the critical factor).

If you have any questions about composting, please contact a member of the Penn State Extension Poultry Compost team: Torey Fischer at 717-363-9059, Ashley Bigge 717-334-6271, or Gregory Martin at 717-9258-789. This team also offers farm visit consultations for those interested in using composting for routine disposal of mortality, manure, offal, or other animal products.

Review by Dr. Ashley Bigge and Dr. Greg Martin, Penn State Extension Poultry