Composting is a manure management option to consider if you don’t have enough land for manure application. Composting can easily be done with manure from shallow or deep bedded systems and has been done using liquid manure directly by blending it with straw or other materials. Benefits to composting include weed seed and pathogen kill, elimination of odor during manure storage and field application, and the creation of a potentially marketable product.
Managing hog manure as a liquid has been the least-cost option and can be one of the most effective methods for conserving manure nutrients. Changes in legislation may restrict when and how much manure can be applied to agricultural land and therefore, increase the costs of this process. The simplest way to reduce manure management costs is to reduce the amount of water in the manure. Separating liquid from hog manure for the sole purpose of composting the solids may not be viable because of the high cost of separation.
An agitated bed composting process allows additional liquid to be added. The liquid manure composting process can be manipulated to increase moisture removal through evaporation. This results in a concentration of nutrients in the manure, as well as producing a product that is easier to transport and utilize. The risk of environmental pollution is reduced with compost application to land because the biological oxygen demand (BOD) is reduced, resulting in reduced risk of surface water pollution. The concentration of inorganic nitrogen is lower, which reduces the risk of surface and groundwater contamination by nitrate.
There are two options for composting, a shallow litter system, followed by composting or overall manure management and reduced the water content of the manure. Composting of the manure following separations is a good option, but more research is being done.