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Title: Energy and nutrient recovery from cattle feedlots

Author
item Eigenberg, Roger
item Woodbury, Bryan
item Parker, David
item Spiehs, Mindy

Submitted to: International Symposium on Air Quality and Waste Management for Agriculture
Publication Type: Proceedings
Publication Acceptance Date: 8/10/2010
Publication Date: 9/13/2010
Citation: Eigenberg, R.A., Woodbury, B.L., Parker, D.B., Spiehs, M.J. 2010. Energy and nutrient recovery from cattle feedlots. In: Proceedings of the American Society of Agricultural and Biological Engineers. International Symposium on Air Quality and Waste Management for Agriculture, September 13-16, 2010, Dallas, Texas. 2010 CDROM.

Interpretive Summary: Manure from cattle feedlots has often been considered a liability; a product that had to be disposed of or stored. Manure has valuable properties which, if concentrated, can make a product of significant value. ARS researchers at the U.S. Meat Animal Research Center have devised a tool to locate areas of highly concentrated manure on the feedlot pen surface. Once located, these specific areas can be harvested and marketed as a valuable product such as a combustion fuel for electrical generation. This work--combined with electronic sensing equipment and special computer software--can locate concentrated manure on feedlot pen surfaces. Selectively harvesting the concentrated manure increases the value of the nitrogen and phosphorus nutrient content. Also, this method showed a value increase of four times when the manure was selectively harvested for energy versus harvesting for nutrient content.

Technical Abstract: Selective harvesting of manure can benefit cattle producers by creating a product of value. A tool that identifies locations of manure accumulation has been developed and demonstrated. A dual geometry sub-surface sensor (Dualem-1S, Milton, ON) was used with software designed for salt mapping (ESAP, Riverside, CA). The combination allowed the development of models to estimate higher heating value (HHV) of feedlot manure across a feedlot pen. Soil sample data from cattle feedlots in Texas and Nebraska were analyzed for volatile solids (VS), then combined with the Dualem-1S apparent soil conductivity (ECa) data to produce models having correlations between ECa and associated VS (r**2**=0.869, VS). A corresponding model is under development to estimate the moisture content of the collectable solids. The combined models allow real-time spatial estimates of HHV within a feedlot pen. These methods will allow direct harvesting of VS for use as a recoverable energy source through direct combustion or co-combustion.