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Processing Alfalfa and Soybeans--On the Spot

By Linda McGraw
January 7, 2000

New products and increased markets for alfalfa and soybeans are on the horizon for Midwest farmers in the next century, thanks to the innovative research of Agricultural Research Service and University of Wisconsin scientists in Madison.

The petroleum industry has long fractionated crude oil into a variety of products, each surpassing the original commodity in value. Now the same idea is being shown to work for crops in a fieldside processing unit devised by ARS agricultural engineer Richard G. Koegel at the U.S. Dairy Forage Research Center.

Until now, the process--called wet fractionation--was conducted in a central processing facility. The drawback: Herbage, which contains about 80 percent water, had to be transported from the field to the processing facility, and waste liquid needed to be either dehydrated or transported back to the field as liquid fertilizer.

Last summer, Koegel assembled a group of machines in the first fieldside demonstration of soybean herbage wet fractionation. For the most part, commercially available machines were used, but Koegel modified a hammermill--originally used for pulverizing grain by forcing it through screens--to rupture the herbage without reducing fiber size. The work was conducted under a Cooperative Research and Development Agreement (CRADA) with industry.

Demonstrating the feasibility of the concept was the first step toward further development of a mobile field processor. Working like a combine, it cut the crop and wet-fractionated it while juice was being processed in the field. The energy cost for producing 6.4 tons of herbage and 3.5 tons of juice per hour was about $0.76 per wet ton.

Products from the fiber portion include cattle feed, chemical feedstocks, mats for filtering pollutants from water, enzymes derived by growing fungi on the fiber, and building materials. Products from the juice fraction include food- and feed-grade protein concentrates, carotenoids, antioxidants and industrially valuable enzymes.

Scientific contact: Richard G. Koegel, ARS U.S. Dairy Forage Research Center, Madison, Wis., phone (608) 264-5149, fax (608) 264-5147,