Jean Bonhotal
Cornell University
The Cornell Waste Management Institute (CWMI) collaborated with thirty farms, primarily dairy, to evaluate composted manure for a variety of parameters. Because the definition of finished compost was not standardized, the material analyzed varied widely between farms. For the dairy farms, fecal coliform and weed seeds were low and pH, chloride and maturity levels were acceptable. Some dairies that used hoof dip had high levels of copper. For the seven poultry composts tested, some were high in pH and chlorides and low in maturity but all had low fecal coliform and weed seeds. A windrow of dairy manure inoculated with Johne’s disease showed no contamination after six days of composting and similar results were found for finished compost from four dairy farms with high incidence of the disease. One farm that used an anaerobic digester prior to composting achieved good reduction of both fecal coliform and Johne’s. CWMI also assessed the impact of composting dead animals and butcher waste on Clostridium, E. coli, and Listeria and found that results vary with the composting method. The preferred practice is to use large woodchips to allow passive aeration and absorb moisture and to apply the compost to forests and non-root crops.
Discussion:
David Elwell (OSU) asked if attempts had been made to increase the rate of composting by mixing butcher waste with wood chips to increase the contact between nitrogen and carbon sources. Bonhotal replied that the method used is to layer 18-24 inches of woodchips, then 6-12 inches of waste, then 12 inches woodchips, etc. The material is not turned as with manure composting. For blood waste, a trench can be formed at the top of the windrow that contains other feedstock and the blood incorporated from there. The same method has been successfully used for liquid manure as well as waste materials from Ben & Jerry’s ice cream.
Fred Michel (OSU) questioned the composting regulations in New York State. Bonhotal noted that NY regulations are less stringent than Ohio’s. Universities and property owners (e.g., custom butchers) are exempted from permits unless there is a problem.
Michel asked if there was any difference for those selling the compost off-site. Bohnotal said that food waste and manure composters do not need a permit. Biosolids composting facilities must be permitted and yardwaste facilities must register
Srinand Sreevatsan (OSU) asked if containment is used to compost dead animals to protect wildlife from BSE or similar wasting diseases. Bohnotal replied that regulations do not require containment. If the pile is well constructed, there should not be runoff.
Sreevatsan questioned whether pH levels were very high during mortality composting. Bohnotal responded that it is generally not the case.
Elwell asked if there were any data to indicate that the prions that cause the mass wasting diseases breakdown when applied to fields after composting. Bohnotal responded that to date, the only way to disable the prion is by alkaline digestion. Sreevatsan noted a National Institute of Health study that found no deterioration of the prion when infected brains were buried (no composting). Elwell suggested that something, perhaps a bacterium, seems to destroy prions over time otherwise there would be more incidences of infection.
Warren Dick (OSU) noted that as a soil scientist he has never found a protein that will not degrade in soil. While a prion (a protein) may be more resistant it would appear that they do degrade otherwise greater accumulation in the soil would be expected. Sreevatsan suggested that some may not agree with that conclusion.
Dick asked for the source of the copper found in some of the composted dairy manure. Bonhotal said that copper sulfate is found in some hoof dips which are used to control problems with hoof diseases that tend to occur in the high moisture environment associated with liquid manure systems.
Michel asked whether the higher concentration of fecal coliform in the edge of the windrow compared to the middle could be the result of temperature differences. Bohnotal noted that the difference was found in storage piles that had been turned. The fact that the middle of the pile had lower concentrations than the edges was unexpected as the middle is wetter.
Sreevatsan asked whether it is acceptable to spread composted manure after 6 days of composting since the data indicate that Johne’s disease had been eliminated by then. Bohnotal responded that veterinarians have given the ok but for animals on pasture, more mature compost is more palatable for the animals. Also, although Johne’s was not found after day 6 (days 2-5 were not tested), there is a possibility that it still exists as it may be found in isolated areas in the compost.
Notes by Mary Wicks
The OCAMM (Ohio Composting and Manure Management) Program is funded by OARDC/OSU.