Abstract
African swine fever virus is a major disease concern for the United States swine industry. The current USDA recommendation for controlling the virus is stamping out. Composting is an acceptable method to inactivate the virus in whole hogs. However, composting slurry/manure has not been researched. This project will address several concerns related to composting slurry/manure.
Swine slurry is the feces, urine, wasted drinking water, wasted feed, inter-group wash water with detergents/disinfectants, dander, insects, and microorganisms (normal and infectious) accumulated in a storage pit located under the slatted floor of a swine production building. It may be called liquid swine manure.
The composting of swine slurry has been studied and proven effective as a treatment prior to use as a soil amendment (Eiland et al., 2001). Previous studies have been completed in a lab or controlled field setting with objectives focused on normal swine farm management. To our knowledge, there are no reports about the mass emergency composting of swine slurry. The significant water content in swine slurry, in the range of 85 to 95%, makes the composting of swine slurry both a decontamination and environmental challenge.
In the Midwest U.S., corn stalks and corn stover are plentiful composting amendments to be used in emergency response plans for poultry. It will be used if a swine HCD response is undertaken. With water contents of swine slurry as mentioned above and a book value of 12% water in ground corn stalks, we estimate that it would take 5,792 yd3 to compost a full pit (538,610 gallons) of a 1200 swine facility. Absorption of water and nutrients from swine slurry poured over the top of an amendment will be dependent on several factors, including the amendment used, the depth of the amendment, ambient temperature, humidity, and the amount of conditioning (mixing with the physical effects of increasing amendment surface area and opening the hard waxy surface of stalks and stems). Researchers in China studied the absorption of swine slurry into mechanically treated corn stalks and observed that water absorption by conditioned stalks was about 500% of its weight in about 4 hr. It took 12 hr. for complete absorption (1000% of stalk initial weight; Jiao et al., 2022).
If composted on-farm, we do not know how much slurry we can apply to various available amendments. Probably, many farms would not have equipment to condition or mix the slurry and amendment prior to laying down windrows. The degree of absorption and how much will run through a ‘bed’ of amendment is not known. Because composting in a highly consequential disease emergency response will result in pathogen inactivation, we have planned this study to gain practical experience with composting swine slurry.
