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Published March 06, 2013, 12:00 AM


Pat Zimmerman (left) and his son, Scott, run C-Lock Inc., a company based in Piedmont, S.D., near Rapid City. They design, build, market and service a system they call GreenFeed. It measures methane and carbon dioxide output on cattle for scientists and cattlemen. Photo taken Jan. 28, 2013, at Piedmont, S.D. (Forum News Service/Agweek/Mikkel Pates)
Read the article: Measuring methane