Start Date: May 21, 2005
End Date: May 09, 2010
Objective 1 - The hypothesis to be tested is starch, nonstarch carbohydrate, and protein excretion in manure differ by diet, and these compounds are differentially utilized by microorganisms to produce malodorous compounds, ammonia, and greenhouse gases. Multiple experiments will evaluate swine and cattle manure from diets differing in starch, fiber, and crude protein contents from diverse feed sources in order to determine the effects that diet has on 1) odor compound production and emission, 2) nitrogen transformation and loss, and 3) greenhouse gas emission. Manure slurries and soil/manure mixtures mimicking feedlot surfaces will be incubated over time at ambient temperature and analyzed for microbial fermentation products including straight and branched chain volatile fatty acids, aromatic, sulfur-containing, and nitrogenous compounds, alcohols, and the greenhouse gases-methane, carbon dioxide, and nitrous oxide. Follow-up field studies will seek to validate results from the laboratory by monitoring the production and emission of compounds of concern from the production environment. Objective 2 - The hypothesis to be tested is moisture content, the ratio of manure to soil, and the temperature of the feedlot surface are the dominant factors that contribute to an anaerobic microbial environment on the feedlot surface, which produces more offensive odor compounds, enhances detrimental nitrogen transformations, and contributes to greater greenhouse gas production than an inactive or aerobic microbial state. The approach will be to evaluate a range of environmental conditions affecting dominant microbial physiologies (inactive, aerobic, and anaerobic) in multiple manure and soil incubations which vary the manure moisture content, manure to soil content, and temperature. Conditions favoring beneficial microbial activities (N immobilization, odor compound consumption, and nitrification/denitrification) relative to unfavorable activities (ammonia production and emission, odor compound production and accumulation, and greenhouse gas emission) will be targeted for further characterization and ultimately evaluated in field experiments. Objective 3 - The hypothesis to be tested is a combination of plant essential oils and urease inhibitors will limit microbial activities in stored cattle and swine manure that lead to odor compound production, ammonia formation, and greenhouse gas emissions. Once an effective compound, both in least cost and inhibiting properties is selected, it will be evaluated in the laboratory with a urease inhibitor for control of ammonia and odor emissions. This combination of the urease inhibitor and plant oil will also be incorporated into a granule material. The granule will be evaluated in the laboratory for effectiveness in releasing the chemicals from the granule by quantifying volatile fatty acids, urea, and ammonia in cattle manure slurries. Field studies in a cattle feedlot will be conducted with the granule containing the two chemicals. Field studies in an anaerobic deep pit swine production facility without the granule will also be conducted.