Tools to Address Air Quality Concerns
By Wendy Powers, Michigan State University; Angela Rieck-Hinz, Department of Agronomy and Jay Harmon Department of Agricultural and Biosystems Engineering, Iowa State University
Emissions from livestock operations come from three main sources: animal housing, manure storage and land application. In some cases, feed storage may also contribute to overall emissions, depending on the type of feed and the storage method. The relative contribution of each source is site-specific and highly dependent on the species and the type of housing, manure storage and land application methods. Variations exist within a species, too.
For example, a pull-plug swine nursery barn will have different odor and gas emissions than a deep-pit swine finishing barn because of the way the building and manure within the building are managed. The two facilities will also have very different relative contributions from the manure storage area, largely because the finishing barn may not have additional storage. Similarly, a tie-stall dairy barn with only winter manure storage facilities may have vastly different mitigation strategies from that of a freestall dairy facility that has manure storage under the free-stall area and in a concrete tank. And the turkey or broiler chicken grower who raises multiple flocks on the same litter has still another completely different set of considerations.
Assessing where to invest
With limited resources to devote to reducing air emissions, producers are faced with the daunting task of deciding where to invest. To make a wise investment, you need to establish objectives. What do you want to control -- odor or a specific gas, such as ammonia or hydrogen sulfide? Or do you want to reduce emissions of particulates (dust) or a group of gases, such as volatile organic compounds (VOCs).
Once the objective is established, you need to know how much control is necessary. In some cases, established guidelines, rules or regulations may set the benchmark. But in many cases, there are no established benchmarks -- you need to make your own decision on how much emission control you want to have.
With emission control benchmarks set, you need to decide which mitigation strategy to employ. To realize the biggest return for your investment, use assessment tools to identify problem areas that should receive priority attention. If most odor concerns arise when you’re cleaning out the concrete manure storage area, for example, do not start with a strategy that would be used in the barn. If complaints arise from neighbors nearest the fields where manure is applied, then invest in your land application method, not in a manure storage cover.
After the high priority area or areas have been identified, it is time to select a mitigation strategy. This can be a hard and costly decision. Take care to ensure that the strategy is compatible with current management and will result in meeting the reduction targets. A tool available through Iowa State University, the Air Management Practices Assessment Tool (AMPAT), found at http://www.extension.iastate.edu/airquality/practices/homepage.html, provides assistance in making this decision.
AMPAT asks a series of questions designed to help narrow the available strategy options based on the current management system. The remaining options all have corresponding reduction for odor, ammonia, hydrogen sulfide or dust, and a relative cost associated with their implementation. AMPAT also provides a list of additional resources for more information about any particular strategy.
AMPAT helps narrow mitigation strategy options, but it does not help identify priority areas for implementation. To fill this gap, in September 2008, the USDA Natural Resources Conservation Service awarded a grant to 12 universities to develop a national air quality self assessment or third party assessment tool (AQSAT) that will enable livestock producers to best decide how to reduce air quality concerns. The result of the two-year project will allow a producer to walk through his or her site and determine where a mitigation practice can have the greatest impact on air quality. Producers will be able to select a gas of interest or odor as their primary reduction objective and from there decide where to implement a mitigation strategy as well as estimate the benefit of any strategy considered. Following development, this multispecies tool will be on-line and available to all producers considering a new operation or an expansion, or those wanting to reduce emissions from their existing operations.
States involved in the project are California, Colorado, Georgia, Indiana, Iowa, Maryland, Michigan, Minnesota, Nebraska, Oregon, Pennsylvania and Texas. In many states, Extension has partnered with state livestock associations to develop and field test the tool. The geographical distribution of project partners will allow for a tool to be developed that meets the needs of dairy, beef, swine, turkey, laying hen and broiler chicken growers across the country.
AQSAT in Iowa
The Air Quality Self Assessment Tool has been under development by a team of national scientists for the past year. The Iowa delegation to this team consists of two Iowa State University campus based specialists and five ISU extension field specialists. Currently, the Iowa team is field-testing the tool on swine, beef, turkey and layer farms in Iowa. It is anticipated the field testing will be complete in fall 2008. Upon completion of field testing, the tool will be finalized and developed into a Web based program accessible to those interested in using the program to determine where air emission control practices can be implemented on their farms. The final assessment tool is expected to be complete in fall 2009.