Authors: Chip Simmons, PhD, Assistant Research Professor at the University of North Carolina at Chapel Hill, School of Public Health, and Mark Rice, Extension Specialist at North Carolina State University
Farm-specific information (land available, hauling distances, etc.) on a case-by-case basis is needed to answer this question and is based on the economics of the individual situation. Based solely on an on-farm economic standpoint, it is doubtful that there will be any technology "lower cost" than lagoons or pits, but if hauling distances are great, solid/liquid separation may help reduce cost by reducing the volume being transported to distant fields. Unfortunately, solid/liquid separation of swine waste, without the proper specialized equipment, is not particularly efficient, especially following storage. One of the reasons that anaerobic lagoons are not used in these locations is that, with the lower average temperature (anaerobic lagoons rely on biological processes which slow considerably with cold temperatures), a lagoon system would need to be several times larger to accomplish the same degree of solids and odor treatment. Some literature demonstrates as much as two to three log10 reductions for several classes of microbial pathogens using thermophilic (>55°C) anaerobic digestion. However, this technology generally does not fit the request for a “lower cost alternative.”
In situations where treatment technologies that greatly reduce pathogen concentrations are not available, other barriers to pathogen transmission must be considered including reducing the potential for pathogens entering the farm and cross animal contamination within the farm (http://lpe.unl.edu/pathogen5.html#q1) and limiting movement of pathogens associated with land application practices (http://lpe.unl.edu/pathogen5.html#q2)
Author: Dr. Mark Risse, Professor of Biological and Agricultural Engineering, University of Georgia, mrisse@engr.uga.edu
There are numerous BMPs that work in land application areas when liquid manure is applied. As stated in the Web cast, we can control either the source or the transport. Source control strategies related to application can include application method and timing. Subsurface injection or incorporation will move pathogens beneath the soil surface and make transport more difficult. Applying manure during periods of hot, dry conditions will encourage die-off of most pathogens, and avoiding periods where rainfall and runoff are likely will reduce the opportunity for transport. Likewise, applications on snow-covered or frozen ground should be avoided since pathogen persistence and the likelihood of runoff are greater. Since most pathogens are transported in overland flow or adsorbed to sediment, any BMPs that encourage infiltration or reduce transport of sediment and nutrients should also work with pathogens. Buffers and filter strips around field borders have been proven to reduce pathogen loads, with reductions ranging from 20 to 99% depending on a number of factors such as buffer width, slope, vegetation, and contributing area.
Diversions to keep overland flow from running through land application areas and methods that trap sediment in runoff such as sediment basins and ponds are also effective on pathogens. Standard BMPs and their associated NRCS practice codes that are effective on pathogens include:
Dike (356), Diversion (362), Filter Strip (393), Grassed Waterway (412), Irrigation Systems (441, 442, 443), irrigation Water Management (449), Nutrient Management (590), Pond (521), Runoff, Management System (570), Sediment Basin (350), Terrace (600), Water and Sediment Control Basin (638).
To access these NRCS practice codes, go to http://www.nrcs.usda.gov/technical/efotg/, click on your state, and then click on your county. Next open “Section IV” (left-hand column) and “Table of Contents” to find individual practices.
