Wind Tunnel Testing of Dust and Gaseous Emissions from Swine Production Facilities
James Iverson, William James, Bruce Munson

A considerable amount of the odor from swine confinement facilities comes from wind-carried dust particles blown from the buildings. A set of experiments utilizing model buildings within an environmental wind tunnel was conducted to investigate how the dust is eventually deposited downstream of the facility and what can be done to cause more of the dust to be deposited near the facility rather than on adjoining property. Specifically, the role that shelterbelts have in this situation was investigated. it is shown that appropriate use of shelterbelts can significantly reduce the amount of odor-bearing dust that gets transported to adjoining property.

Use of Plants and Plant-Associated Microbes to Reduce Odor Emission from Livestock Production Facilities
G. A. Beattie¹, A. DiSpirito¹ and L. Halverson^1,2. ¹ Dept of Microbiology, Immunology and Preventive Medicine and ² Dept of Agronomy

We are exploring the potential use of terrestrial plants and their associated microbial communities for reducing the intensity of odors emitted from livestock production facilities. The large surface area of a stand of plants may serve as a natural biofilter for the odors emitted by an odor source, such as a waste lagoon or a confinement building. We are exploring both the ability of plants to adsorb odors, by gaseous diffusion as well as impaction and sedimentation of particles, and the ability of plant-associated microorganisms to degrade those odors as they become available on the plant surface. To evaluate the adsorption potential of lipophilic plant cuticles, we are developing methodologies for the recovery and analysis of volatile organic compounds (VOCs) from leaves, using both corn and soybean as model plants. To identify microorganisms that are capable of both odor-degradation and growth and survival on leaf surfaces, we have obtained leaf-surface bacteria from plants located immediately downwind from several hog waste lagoons, enriched for organisms capable of degrading various, and identified the resulting 10 strains that exhibited degradation abilities. In future studies, we will be evaluating differences among plant species in their ability to adsorb VOCs and the extent to which adsorbed VOCs are available to these leaf surface bacterial isolates.

Effect of Animal Manure Applications on Crop Yields and Soil Quality
Randy Killorn, Alfred Blackmer and Antonio Mallarino. Dept. of Agronomy

           Policymakers in Iowa have recently stated that expansion of livestock (especially swine) production can increase the economic well-being of the state. New production facilities tend to be large, specialized and rely more in purchased feed that in the past.Unused nutrients in the animal manure must be exported from the confinement facilities. Nitrogen (N), phosphorus (P), and other elements and compounds in the manure pose serious environmental risks if not properly managed. Complicating the issue of proper management is the fact that soils in the areas where animal production is expanding contain adequate to excessive amounts of P and potassium (K) for crop production.
    Utilization of the nutrients contained in animal manure should allow crop producers to reduce the amount of commercial fertilizer purchased. This should reduce costs and increase profits. Because a portion of the nutrients in animal manure are in organic form it is not know with any certainty what rates of animal manure must be applied to supply the nutrients needed for crop production. The rate that the organic forms of nutrients become available to crops depends on temperature and rainfall which vary from year to year.
      Given the current interest in the effect of agricultural activities and the rapid expansion of the livestock industry it is imperative to determine the effects of animal manure applications on crop production and the environment. The objectives of the proposed research are to find animal manure application rates and frequencies required for optimum crop production under different crop rotations and to find the impact of manure applications on soil quality.
    The components described in this proposal focus on how land application of liquid swine manure affect crop production and soil quality. We intend to find how time, method, and rate of liquid swine manure application affect mineralization and nitrification rates (Dr. Alfred Blackmer), phosphorus availability (Dr. Antonio Mallarino), and corn and soybean yield and recovery of nutrients (Dr. Randy Killorn). All the components are based on the assumption that funding will cover three growing seasons and allow time for preparation of a final report following harvest in the final year. The final report will include an economic analysis of the crop production data to help decide the type of manure management that should be recommended.

Building Ventilation Strategies for Reducing Livestock Odors
Steven J. Hoff, PhD (Project PI)

    Ventilation air from livestock production systems contain dust particles and odor producing compounds. Several strategies over the past 25 years have been used to reduce odors from this source. In some European countries, bio filters and bio scrubbers have been successfully implemented into existing livestock production facilities. The efficiency in odor removal has been shown to be very high, approaching 100 percent in some reported studies. The major disadvantage of either technique is cost. Past research indicates capital and operational expenses that can reach $7 (1997) per pig produced.
    This research project has focused on inexpensive air filtration methods using the fact that some odors will adhere to airborne dust particles, as past research has suggested. The hypothesis of this research is that if the majority of particles can be removed from ventilation air, then a significant capture of odor-producing compounds will result. Simple biomass filters, using chopped corn stalks, have been developed and tested in a full-scale testing chamber attached as an annex to an existing swine facility. Particles larger than about 10 microns have been effectively removed using this strategy. Odor threshold reduction using these filters has varied between about 40 and 70 percent. The results point out that simpler strategies, such as natural shelter belts using fast-growing trees, could be used to provide odor filtering via absorption of odor producing compounds. The Departments of Forestry, Microbiology, and Agricultural and Biosystems Engineering are actively reviewing this topic.

    Field studies were initiated in the fall of 1993 to evaluate the effects of nine alternative nitrogen (N), tillage, and crop management strategies on N loss to the shallow groundwater. The tillage and N management treatments included in this study were the use of the late-spring nitrate-nitrogen (NO3-N) test (LSNT) and a reduced N application rate of 100 lb/ac from liquid N fertilizer applied to corn grown in a corn and soybean rotation with either no-till or chisel plowing as the primary tillage practice; and the use of swine manure as the N source for corn grown in rotation with no-till soybean. Alternate crop management strategies included continuous corn either fertilized with liquid N fertilizer or swine manure at a rate of 120 lb-N/ac, a narrow-strip cropping configuration that included corn, soybean, and oat followed by a N-fixing berseem clover cover crop, and three years of alfalfa followed by corn, soybean and oat rotation.
    Experiments were conducted on 40 one-acre plots in north central Iowa. The first four years (1993-1996) of data clearly indicate that lower NO3-N concentrations can be obtained in the shallow groundwater by reducing N application rates to 100 lb/ac. Use of the LSNT and differential N fertilization rates based on that test resulted in the lower NO3-N concentrations in subsurface drainage water under both no-till and chisel plow treatments when compared with manure application or single N application rates of 100 lb/ac.
    The results of this study indicate that with LSNT and single N applications of 100 lb/ac, it is quite possible to bring NO3-N concentrations in the drainage water close to or even below 10 mg/l (a drinking water standard). The alfalfa-corn-soybean-oat rotation and narrow-strip crop plots resulted in the lowest NO3-N concentrations (<10 ppm) in the subsurface drainage water at this research site.
    The difficulty in applying the exact amount of N from swine manure affected the NO3-N leaching to subsurface drainage water. The four year (1993-96) average NO3-N concentrations in the drain water from manure plots were 22.1 mg/l under continuous corn and 14.1 mg/l under corn-soybean rotation. Four years data from this study indicate that several N management practices (lower N application rates and LSNT) and cropping systems have the potential to manage water quality problems while maintaining the sustainability of production systems.

Integrated Composting Systems for Swine Manure Treatment
Tom L. Richard, Jeffrey C. Lorimor and Tom Glanville. Department of Agricultural and Biosystems Engineering. Iowa State University

    This project is developing strategies to compost swine manure and produce a readily stored, value-added soil amendment. Progress during the first few months of the project has focused on two fronts: 1) characterization of the bedded pack resulting from hoop house production, and 2) evaluating the efficiency of a "biomass filter" to separate solids from a liquid manure stream. Initial results from each of these efforts have been very positive, as outlined in detail below.

Hoop-House Bedded Pack
    The recent widespread adoption of hoop housing has occurred with little consideration of manure management issues. The first task of this project has been to characterize the bedded pack, so that successful mixture ratios can be developed for the composting trials.
    Two intensive sampling efforts at the I.S.U. Rhodes Research Farm have been completed. The first sampling event occurred in late February while the pigs were still in the structure, and the second occurred in late April after all animals had been sold. In both cases a bi-modal distribution of moisture was observed, with the majority of the bedded pack dry (17-31% H2O) and a limited area which the animals were using for dunging quite moist (67-78% H2O). Although nutrient concentrations were much higher in the wet zones where manure was deposited, wide variations in nutrient concentration were observed throughout the bedded pack. The primary dunging area was along the west wall, with narrower areas along the north and south walls. It was evident that some heat was being generated by the bedded pack, particularly in the drier regions and along the interface with the dunging area. Thus it appears some unmanaged composting is already occurring within the bedded pack.
    The average moisture content of all the samples collected was 56% (wet basis). This moisture level is expected to be suitable for composting (for which optimum moisture is normally 40 to 60%), so initial composting trials will be without any additional amendment addition. The average nitrogen content is higher than optimal for composting (resulting in a C:N ratio of 15:1), so we will be monitoring ammonia emissions and both ammonia and nitrate in any leachate generated during the composting trials.
    Data acquisition and some monitoring equipment for the composting trials have arrived, and additional sensors and pilot-scale equipment have been ordered. The graduate student who will be assisting with this project is arriving on May 15, and composting trials will be starting shortly thereafter.
    Initial pilot-scale experiments will focus on defining the upper end of moisture content acceptable for composting swine manure mixtures, so that subsequent trials with wet solids from separated manure can be operated with minimal amendment additions. A pychnometer is currently being constructed and tested. The pychnometer will be used to characterize porosity for these high moisture mixtures, and examine the effect of different bulking amendments. Plans call for completion of six pilot-scale composting trials by December, 1997. In addition, full-scale demonstrations with several farmer-cooperators as well as two ISU research farms are in the planning stages, and we hope to monitor 3 such demonstrations by the end of the year.

Biomass Filter
    The "biomass filter" is a new approach to liquid/solid separation. The concept is to use readily available crop residues as a filter media for manure. When the filter clogs and removal efficiency is reduced, the filter/manure mixture will then be processed through composting.
    Preliminary field tests were conducted using a simple 2 gallon plastic bucket with numerous large holes drilled in the bottom. The bucket was filled with a 9 inch depth of soybean stubble, and manure from the Swine Nutrition Management Research Center reception pit was poured through it. The manure was tested for solids contents before and after the "filtering" process. Two trials showed a 54.3% and a 60.2% total solids removal as a percentage of initial total solids content. Initial solids concentration was 1.86%. The manure ran through the bucket quickly, and allowed little if any detention time, so solids removal was attributed to filtering rather than settling. Solids removal from swine manure using mechanical separators such as screens is typically in the 20% range. This successful field test is the basis for designing the laboratory cylinders that will be used for the actual tests.
    Construction of the equipment and instrumentation to be used for laboratory tests is underway. The graduate student who will be doing the biomass filtration work has completed a literature review, and will be starting the actual tests as soon as the equipment is ready, estimated to be in May.
    The laboratory tests will provide some answers as to how long each batch of residue can be used and how quickly it will plug. Influent solids content will be varied to see how this affects the results. Tradeoffs in solids removal efficiency, filter replacement frequency, and filter material requirements will be analyzed to determine how the technology can best be applied in the field. Spent filter material with separated manure solids will also be characterized and utilized in composting trials.

Future Plans and Expectations
    The above discussion outlines the plans for completion of the first year funding (through December 31, 1997). Because this project was funded mid-cycle and we are entering the final year of support, the second year's activities noted in the original budget and timeline (which started in March 1997 and extended to December 1998) will need to be compressed so that the entire project is completed by June 30, 1998.
    Second year activities will include data analysis and modeling of the results from the experimental program described above, full-scale demonstration of the biomass filter, and the development of a menu of realistic scenarios for the integration of composting with swine manure management systems. These scenarios will be designed so that farmers can realistically evaluate composting options with respect to cost and implementation requirements. The scenarios will be packaged in an extension publication, which will serve as a key deliverable of this project.

Development of a microbial community-based diagnostic tool to indicate potential odor emission from swine waste storage systems
Larry J. Halverson^1,2, Gwyn A. Beattie², and Alan DiSpirito². Departments of Agronomy¹ and Microbiology². Iowa State University of Science and Technology

   We are exploring the microbial community ecology of swine waste storage systems to further our understanding of how microbial communities influences the production of malodorous compounds. Regardless of whether the waste is stored in lagoons, deep basins, or pits underneath confinement buildings, it is the metabolic activity of the resident microbial communities that determines the magnitude of the odor emission. Unfortunately, we have a poor understanding of the microbial community characteristics of the metabolically diverse groups organisms that are present in these systems. This knowledge gap makes it difficult for producers to determine how normal management practices or odor reduction technologies influence microbial communities and the extent of odor production. One observation that has been made is that the extent of odor emission can vary among manure storage systems and seasonally within a particular storage system. Our hypothesis is that a relationship exists between microbial community structure and the extent of odor emission and that, within a particular storage system, seasonal changes in community structure influence odor emission. Our goal is to elucidate the relationship between microbial community structure and malodor production. We have been using whole community fatty acid methyl ester (FAME) analysis to develop a profile of the microbial community in various types of storage systems (phototrophic and non-phototrophic one and two stage-lagoon systems, and concrete basins). We have been examining the seasonal variation of FAME profiles over two a year period and are attempting to link that to seasonal variation in the amount of odor indicator compounds that are present in the air and manure slurry as well as to various other physical, biological, and chemical parameters of the storage systems. Ultimately, our long-term goal is to use this information to develop a rapid, inexpensive microbial community-based diagnostic tool for producers to evaluate how management practices influence odor emission potential of swine waste storage systems.