Agricultural odors are an unavoidable part of livestock production and are emitted from every poultry operation. These odors along with the growth of the poultry industry have sparked debate, concern and action in many U.S. communities. Air and water quality have become major issues, along with social and economic concerns. These concerns stem from the fact that the difference between “the city” and “the country” is becoming increasingly difficult to distinguish.
Today, a rural family is not necessarily an agricultural family. The gap is wide between an agricultural family that understands that odors are a part of production agriculture and a rural family that recently moved from the city with little or no tolerance for agricultural odors. Therefore, it is important that poultry producers have a basic knowledge of odor control strategies and do their best to accommodate non-farming neighbors.
Odor Causes
Some odors are generated by the poultry or livestock themselves, and some by the feed, but the most objectionable odors arise from manure and manure decomposition. More than 200 odor-generating compounds have been identified from microbial decomposition of manure. This means that the intensity of the odor depends upon microbial growth and that growth rate will vary with moisture content, pH, temperature, oxygen concentration, and other environmental factors. This is illustrated by the fact that, as temperatures decrease with onset of cooler, autumn conditions, microbial activity slows, which is why odors are generally less noticeable in the cooler months. Yet odors vary greatly, and the offensiveness of each odor is dependent upon the person(s) smelling the odor. Poultry and livestock odors originate from three primary sites or activities: 1) livestock facilities and the housed livestock within, 2) manure storage facilities, and 3) land application of manure. While land applying (spreading) poultry litter is a common practice in many areas, be aware that most odor complaints are associated with land application of manure, not storage facilities or housing.
Understanding Odor
Several different criteria may be used to evaluate odors. Familiarity with these parameters will help producers better understand odor source and interpret odor data.
Odors evaluated as:
1. Concentration (threshold)
2. Intensity
3. Persistence
These three variables are often used to provide regulatory and scientific personnel with some measurement of odor potency and how long the odor is likely to remain. Hedonic tone and character are more subjective measurements that are not typically used for regulatory purposes. The amount of odor emitted from a particular farming operation is a function of animal species, housing types, manure storage and handling methods, size of the odor sources and the implementation of odor control strategies. A variety of strategies and innovative technologies are available for odor control. Some work better for liquid-type wastes (lagoons) while others are equally effective for both liquid and dry manure situations. Technologies that capture and treat odors include manure storage covers, organic mats and biofilters. Technologies capable of dispersing or masking odors include vegetative windbreaks, windbreak walls, proper site selection, adequate setback distances and deodorant or masking agents. However, before adopting any method, producers should consider applicability, effectiveness, costs and labor or management requirements of all available technologies.
Be Proactive
Most people today are generations removed from the farm and have little or no association to agriculture. Therefore, to most of the general public, this lack of association means that in their thinking, agriculture continues to decline in importance. Their only relationship to the poultry industry may be to complain about dust, odors, noise or someone spreading litter, which leaves a negative impression of poultry farming. Producers should be aware that perception is reality for many people, particularly folks with no understanding of modern agriculture.
Visual perception has a huge influence on how much or how little people will accept before a complaint occurs. Well-maintained production units usually are not perceived to smell as bad as units that look uncared-for and run-down. Livestock farmers in the U.S. are under increasing pressure to reduce odor emissions from their property and must become more proactive in addressing the issue. However, the current financial environment dictates that farmers identify control strategies that can be implemented with minimal cost. For example, the planting of trees around farmland or buildings has been identified as a potentially effective, low-cost measure to enhance ammonia recapture at the farm level and reduce long-range atmospheric transport. Properly planted and well-maintained windbreaks can serve a number of functions. Windbreaks that shield poultry houses from the view of passers-by may decrease the chance of odor complaints since people who cannot see the source of an odor, are less likely to: 1) notice the odor in the first place and 2) complain about it. Windbreaks cause the air to be lifted up and over the windbreak, which causes mixing of fresh air with odorous air, thus diluting the odor effect.
Many nuisance complaints occur shortly after litter has been land applied. Producers should carefully select the time when litter will be spread. Let neighbors know when you plan to spread litter. Keep an open line of communication with anyone who may be affected by the spreading of litter from your operation. Avoid weekends and holidays, pay attention to wind direction and once started, finish as soon as possible so that you limit the generation of dust and odor. Spread litter during the morning as much as possible because as air warms it will rise, which lifts odors upward for mixing and dilution with fresh air, and this will also dry litter. Neighbors are less likely to complain if they know you are aware and attempting to address their concerns. Always be courteous when dealing with neighbors, even if you may be unable to comply with all their wishes. In short, be a good neighbor.
G. Tom Tabler is with the Center of Excellence for Poultry Science, University of Arkansas. A full list of sources for this article can be found on our website at www.ozarksfn.com.
