Salmonella from eggshells in composting?
Given the pervasive level of salmonella in our egg supply, is there a concern about composting the shells of uncooked eggs in our gardens? We have a turnable compost bin that "cooks" the food waste. Does this help or even matter?
Wayne County Michigan
First, I want to assure you that eggshells in your compost are okay; they are a rich source of calcium and other nutrients. Crush them down—they take so long to decompose, often they are still clearly identifiable after the compost product is finished.
Next, a little bit about Salmonella bacteria. The bacterium Salmonella has several genus and subgroups. Not all of them are transferable to humans, but all of them exist in the environment all the time. We are always exposed to this bacterium. That is why hand washing is consistently advertised as a public health measure. The food industry takes many steps to ensure the safety of the food that comes from farms to the consumer. This page outlines one such system: http://en.wikipedia.org/wiki/File:Prevention_of_Salmonella_from_the
The type of Salmonella that lives in the chicken often gets transferred to the shell and then to the egg as the shell is cracked. Cooking your eggs kills these bacteria—so does the hot composting process, which can bring the temperature above 140 to 160 degrees F. Hot composting can kill a variety of pathogens and weed seeds (see http://web.extension.illinois.edu/homecompost/science.cfm for more information). Overall, after the composting process is finished and cured, most pathogens will be brought to a similar level as the surrounding soil.
Here is a nice composting blog that has an insightful piece about eggshells in compost: http://www.compostjunkie.com/compost-eggshells.html. To learn more about composting, try these websites: