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Title: Using electromagnetic induction technology to predict volatile fatty acid, source area differences

Author
item Woodbury, Bryan
item Eigenberg, Roger
item Varel, Vincent
item LESCH, SCOTT - University Of California
item Spiehs, Mindy

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/19/2010
Publication Date: 8/2/2010
Citation: Woodbury, B.L., Eigenberg, R.A., Varel, V.H., Lesch, S., Spiehs, M.J. 2010. Using electromagnetic induction technology to predict volatile fatty acid, source area differences. Journal of Environmental Quality. 39:1-7.

Interpretive Summary: Sampling methods have been adapted to measure manure accumulation on feedlot surface. This study was done to determine if these methods could be used to identify differences in odor given off by the manure. Steers were fed either a diet based on corn byproducts left over from ethanol production or a diet based on field corn. Soil samples were collected from the pen surfaces to determine differences in odor production based on diet. No differences were measured in the amount of manure accumulated when the two diets were fed. However, pens with cattle fed the corn byproducts diet produced greater amounts of odor compounds that are considered offensive. This finding is similar to other research conducted in laboratories. Understanding the impact of diet on odor produced can be used to develop ways to manage beef feedlot to reduce offensive odors after a rain event.

Technical Abstract: Subsurface sampling techniques have been adapted to measure manure accumulation on feedlot surface. Objectives of this study were to determine if sensor data could be used to predict differences in volatile fatty acids (VFA) and other volatiles produced on the feedlot surface three days following a rain event. Twenty soil samples per pen were collected from pens with cattle fed two different diets (four pens per diet) using a predictive sampling approach. These samples were incubated at room temperature for three days to determine fermentation products formed. Fermentation products were categorized into acetate, straight-, branched-chained, and total VFAs. These data were used to generate calibration models to predict constituents based on sensor data. No differences were measured in average volatile solids (VS) concentration of accumulated manure when the two diets were fed. However, manure from cattle fed a corn-based diet had significantly (P less than,equal to 0.1) greater average straight-chained and total VFA generation than pens where WDGS were fed. Alternately, pens with cattle fed WDGS had significantly (P less than equal to 0.05) greater branched-chained VFAs than pens with cattle fed a corn-based diet. Many branched-chain VFAs are considered to be more offensive odor than straight-chained VFAs; therefore odors emitted from WDGS manure would likely be more offensive. We conclude diets can affect the types and quantities of VFAs produced three days following a rain event. Understanding accumulation patterns and the ability to predict odorant generation can be used to develop precision management practices to mitigate odor emissions.