Research Initiatives on Environmental Impacts of Intensive Livestock Operations
Terry Church, David Helmer, Darcy Fitzgerald and Peter Dzikowski
Alberta Agriculture, Food and Rural Development, Third Floor, Provincial Building, 4920 - 51 Avenue, Red Deer, AB, Canada, T4N 6K8
Introduction
Livestock production is expected to undergo significant growth to at least 2005 (Toma and Bouma, 1997). Odour from agricultural operations has been identified as an environmental concern and odour reduction is a significant research priority. Other technical concerns often associated with intensive livestock facilities include water quality, health, and soil impacts. Confinement hog operations occupy relatively small areas where the manure is handled and generally controlled to prevent contamination. Manure management practices have a significant role on the minimization and prevention of environmental impacts. A key incentive of Alberta Agriculture, Food, and Rural Development (AAFRD) and other research organizations is to determine and promote best manure management practices.
There are many research institutions in North American and world wide studying various aspects of manure management. Some of these centers excel in certain areas of odour, modelling, water quality, etc. The Silsoe Research Institute is currently researching gaseous emissions and dispersion modelling. The results of this research will be greatly beneficial to Alberta producers considering odour control technology. Producers will feel more confident that the capital and operation costs of odour control will achieve the desired odour reduction. Iowa State University has been involved with odour measurement and control for some time and current research includes odour reduction through dust control (Hoff et al., 1997), lagoon foam cover induction (Bundy, personal communication), and permeable lagoon covers (Bundy et al., 1997). Minnesota State University is one of the first agricultural research facilities to adopt olfactometry based measurements for investigating odours from intensive livestock facilities. They are working on the adaptation of venturi-based odour measurement equipment (Nicolai et al., 1997) currently used in Germany (VDI, 1986) and also recently acquired in Alberta by AAFRD and the Alberta Pork Producers Development Corporation. Although not directly environmentally related, crucial research reported from the University of North Carolina focuses on the psychology of odour impacts to nearby residences (Schiffman et al., 1995).
In this paper we will briefly discuss research initiatives involving AAFRD researchers.
Involvement usually is in collaboration with other research organizations including universities,
other federal and provincial government agencies, and private sector initiatives. The support of
these research studies by industry in the form of direct funding and in-kind support is gratefully
acknowledged.
Research Initiatives
Odour
Odour from hog operations is a major concern for both producers and neighbours. Producers have a strong desire to significantly reduce odour emissions from barns, manure storage, and land application functions. Finding practical and economical odour abatement methods will go a long way to easing neighbour's concerns.
The current and most popular method of odour control is the use of minimum distance separation (or MDS as indicated the Code of Practice; AAFRD, 1995). For a given facility size, a minimum distance to the nearest neighbouring resident is recommended to minimize or eliminate odour impacts through dilution and dissipation. This approach is usually adequate, but may have limitations for new developments and operators who wish to expand existing facilities. Often an existing facility is already at the MDS from neighbouring residences due to subsequent rural development. This situation has major restrictions on expansion potential. Odour control methods can reduce the odour emission levels such that the odour levels after expansion are equal to or lower than the pre-expansion levels. Where odour abatement methods are used, the MDS can be justifiably reduced.
However, research studies are required before this can happen. Odour abatement technologies exist, but they can be costly or impractical for hog producers. The odour emission reduction from many of these technologies has not been adequately quantified. This is a knowledge gap that needs to be filled prior to recommending a reduction in MDS using various odour abatement methods.
Odour is also a very complex issue. Over 160 odorous compounds have been identified (Spoelstra, 1980) in hog odour. Each individual compound contributes to the overall odour character either by making the odours more offensive, easier to detect, or harder to measure. Odour reduction efforts often concentrate on individual components such as ammonia or hydrogen sulfide, but may fail to reduce the overall odour emission levels. Odour is not well represented by individual components (Zhan, 1997), thus requiring a measurement technology that measures "odour" directly.
Research initiatives to measure odour are being developed cooperatively between researchers at AAFRD, Dr. John Feddes, University of Alberta, and Dr. Richard Coleman, Alberta Research Council. Investigation of odour measurement technologies is an initial task in order to properly quantify odour levels and emission reduction using odour abatement technologies. An electronic nose is being developed as a research tool in odour measurement (Abma, 1997). This electronic nose is a computer-based machine that uses 32 different polymer sensors to mimic the olfactory system of people. Volatile gases change the individual sensor's electric conductivity and their response to different volatile gases. Sensors are chosen so that the major types of molecules expected in the odour will trigger the maximum response on at least one of the sensors (Classen et al., 1997). The electronic nose will be tested in parallel with olfactometric odour measurements (Feddes and Coleman, personal communication). Olfactometers use eight to ten human panellists to sniff the odorous air. The dilution level where half the individuals no longer detect the odour is called the "dilutions to threshold". Odour samples with higher measured dilutions to threshold values indicate that it takes more dilutions before the odour is no longer detectable and, therefore, a stronger odour sample.
A research project between AAFRD, Alberta Environmental Protection, and Agriculture Canada
involves studying the similarities between odour and ammonia emissions to determine the odour
emission from barns, lagoons, and field spreading. The University of Alberta and Alberta
Research Council will also collaborate on this research. The research will initially focus on real-time measurement techniques for ammonia using an open path tunable laser diode built by Boreal
Laser Inc. Measurements will determine the atmospheric ammonia concentrations at key
locations which can be back calculated to determine the emission rates from different source types
and under varying meteorological and site specific conditions. Odour measurements will be done
in parallel to the ammonia measurements. This type of information is the basis for the use in
computer dispersion models to predict odour and other emissions at distances downwind of the
source and under different atmospheric stability conditions (i.e., temperature inversions).
Water Quality
Water quality is often a concern with intensive livestock facilities. Manure may contaminate water through excessive nutrient loading, nitrate contamination, high organic loading, and pathogens. Nutrients, mainly in the form of phosphorus and nitrogen, are beneficial to the soil and plants. Manure is considered a resource because of these nutrients; however, when applied in excess, the nutrients may enter water sources and cause eutrophication and high nitrate contamination of ground and some surface waters. Manure also contains high amounts of biodegradable organic matter. These compounds will be biologically oxidized by bacteria, depleting oxygen in surface water and thereby creating undesirable anaerobic conditions resulting in higher fish mortality and lower egg survival. Several microorganisms excreted by pigs are also potential pathogens for humans (Atwill, 1997; Olson et al., 1997).
There are several water quality research initiatives underway by AAFRD in collaboration with other research agencies. A recent study (AAFRD, 1997) looked at the impacts of agricultural practices on rural ground and surface water quality. The five-year study provided evidence that intensive livestock practices have the potential to impact water quality, particularly in high livestock density areas. There was little evidence of contamination in most of the province.
There is considerable interest in identifying the manure management practices to mitigate any water quality and odour emission impacts. Identification of the best manure management practices in order to improve the practices of most producers is a goal of AAFRD. The initiative is expected to commence in 1998.
AAFRD, in collaboration with Agriculture Canada and the University of Calgary, is currently
completing an earthen manure storage study. The purpose of the study was to investigate earthen
hog manure storage sites for leakage using alternative technologies. Traditional drilling was
combined with non-intrusive surface methods to locate potential groundwater plumes. Drilling
was used to collect actual samples of soil and groundwater to check for contamination by
nutrients, salts, and coliform organisms. The non-intrusive methods utilized electrical
conductivity of the potential groundwater plume to determine the location and extent of the
contamination (if any). These methods have the ability to investigate a much larger area in a
relatively short period of time.
Manure Treatment and Nutrients
Hog manure is not generally treated due to the high costs and little obvious benefits of treatment. Separation of solid and liquid manure fractions is a first step in manure handling and is used by some producers to decrease the volume of solids to be handled. SnowfluentTM is an AAFRD initiative (MacAlpine et al., 1997) in collaboration with the Alberta Research Council to stabilize the organics, control the nutrients, and inactivate the pathogens. SnowfluentTM works by atomizing the manure with high pressure and freezing in the snow making process. Water generally freezes pure (as can be attested by the polar ice caps). The ice crystals form pure water, excluding dissolved nutrients and organic matter. The rapid freezing potentially inactivates microorganisms.
Composting is a well established manure treatment process. Olds College and the University of
Alberta are currently evaluating different aspects of composting, including nutrient control,
ammonia volatilization, and compost materials. Hog manure is not usually composted since it is
typically very liquid and lends itself well to other handling methods. AAFRD intends to initiate a
project in collaboration with Elite Swine, Olds College, and the University of Alberta looking at
the potential to inactivate microorganisms, odour and ammonia emissions, and the practicality of
swine manure composting.
Conclusions
The research developed by AAFRD staff with other key research institutions and supported by industry should provide a solid basis for the reduction of environmental impacts from intensive livestock facilities. Odour measurement, prediction, and control are major research efforts intended to provide effective and practical control measures. Identification of the best manure management practices, as well as treatment alternatives, will provide alternatives needed by industry to substantially reduce environmental effects of intensive livestock operations.
Economical investigation methods of lagoon seepage are being considered to find leaks from lagoons at earlier stages before the groundwater plume becomes difficult to manage. The use of non-intrusive methods may become an effective monitoring tool for looking at the entire area adjacent to the lagoon and can better determine the optimal locations for subsequent drilling and contamination confirmation, if required.
SnowfluentTM is being looked at as a potential manure treatment method for the industry.
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