MITIGATION OF DAIRY MANURE ODORS AND GAS EMISSIONS USING MANURE AMENDMENTS AND A FEED ADDITIVE

Development pressures are steadily consuming open space that once served as a buffer between agriculture and competing land uses. Odor related nuisance complaints are on the rise and there is little doubt that malodors threaten the survivability of some agricultural operations. According to several inventories, cattle facilities account for ~90% of ammonia emissions. Ammonia gas is linked to air-borne fine particulate matter (a health concern) and contributes to aquatic N loading when washed from the atmosphere. Greenhouse gases (methane, nitrous oxide and carbon dioxide) originating from agricultural sources are under increased scrutiny by the US-EPA. Animal agriculture is being challenged with a myriad of questions related to odor and gas emissions. Dairy producers are faced with dozens of choices from manure additive vendors with claims of odor reduction potential. Some claims resemble those of the infamous snake-oil salesman while others seem legitimate based on anecdotal reports. Why do some additives reduce odor and/or gas emissions while others offer empty promises? This project will provide a quantitative and scientifically defensible framework for addressing this issue. Odors are difficult to document since quantification remains largely subjective and elusive, unless highly specialized equipment and techniques are employed. Over 160 chemical compounds have been identified in livestock wastes and nearby air. Due to the complexity of odor recognition and interpretation, olfactometry with a trained human panel is considered the ôgold standardö for evaluation of nuisance odors. Penn State is fortunate to have the only olfactometry laboratory in the mid-Atlantic / northeastern U.S. dedicated to agricultural/ environmental odor research. Manure amended with commercial products that promise odor and gas reduction advantages will be studied. One feed additive will also be evaluated. Headspace gases will be sampled for evaluation from flux chambers containing treated manure. Odor units (olfactometry), character, intensity, and hedonic tone will be quantified for each gas sample by a trained human odor panel. Ammonia and greenhouse gases will be measured using a photoacoustic infrared gas analyzer. Where odor reduction is statistically significant, specific odorants (e.g. sulfides, mercaptans, volatile fatty acids, phenols, indole, skatole) will be quantified using gas chromatography to identify dominant malodor compounds in treated versus untreated manure. The assembled research team has been working in gas and odor evaluations of various aspects of dairy management systems for the past four years, and our Penn State Odor Assessment Laboratory is equipped for the controlled-environment laboratory odor assessments planned in this study. Statistical analyses of treatment effects will be conducted by a post-doctorate scholar trained in agricultural data analysis and experienced in the microbial and chemical aspects of biological materials. Relevance to current dairy industry practices and concerns will be assured by inclusion of Extension Specialists in dairy farm engineering, animal nutrition, and management.