ARS | Publication request: Energy and nutrient recovery from cattle feedlots

Submitted to: Scholarly Research Exchange
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 3, 2011
Publication Date: January 13, 2012
Citation: Eigenberg, R.A., Woodbury, B.L., Auvermann, B., Parker, D.B., Spiehs, M.J. 2012. Energy and nutrient recovery from cattle feedlots. Scholarly Research Exchange. 2012:1-5.

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 the 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 using a sub-surface sensor (Dualem-1S, Milton, ON) and 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 and VS (r2=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.