Soybean Protein Concentration Lags Behind World Competitors

Mike Rankin
Crops and Soils Agent
University of Wisconsin - Extension

Note:  University of Wisconsin-Extension has hired a new soybean agronomist in the person of Dr. Roger Borges.  Roger is a native of Brazil but has been in the United States for a number of years and received his graduate training at Iowa State University (this fact alone makes him a "can't miss" hire).  Most recently, he has served as an assistant professor in the Agronomy Department at Iowa State.

        When selecting a soybean variety, protein content is not a trait that is looked to as a primary decision-making criterion.  But then, why should it be?  For an individual soybean producer, there certainly is no economic benefit for selling soybeans that are 37 percent protein instead of 32 percent.  However, Roger Borges, UW Extension Soybean Specialist, makes a good case that low protein soybeans are costing the industry as a whole, and discounting the price paid for U.S. soybeans on the world market.  This ultimately translates to lower prices at the farm gate.  Currently, soybeans from South America are valued more highly, and paid for accordingly, on the world market.  On average, one bushel of U.S. soybeans yields 21 pounds of protein and 11.4 pounds of oil.  Brazilian soybeans yield 24 pounds of protein and 13 pounds of oil.  Simply put, there's more to make out of a bushel of South American soybeans.

OK, what can be done?

        On the research and variety development side, more emphasis needs to put on developing varieties with higher protein content.  Currently, there is a wide variation in soybean protein concentrations both within U.S. geographic regions and among varieties.  Unfortunately, the western Corn Belt and Wisconsin do not compare favorably to other U.S. regions (see chart below).

        Average soybean protein concentration varies from about 0.6 to 2.0 percent between regions depending on the year.  The spread in protein values is much greater between varieties grown in Wisconsin (Table 1). 

"Ya, but with higher protein and oil content, do I have to give up yield?"       

        Analysis of the yield and quality data from the UW Soybean Performance Trials indicates that this isn't the case.  The graph below shows the protein and oil per acre yields plotted against total grain yield in bushels per acre.  Within a given grain yield level, there is a difference of up to 200 pounds of protein + oil yield.  Each dot on the graph represents a single tested variety.

Best approaches to improve protein and oil yield

        Although growers can't do anything about where they farm in the U.S., they can take grain quality into consideration when selecting varieties.  Even so, because there is no direct economic benefit (unless you're growing soybeans for on-farm feed consumption), rank grain quality below other selection criteria such as yield, herbicide resistance, relative maturity, disease resistance, seed cost, and lodging.  Beginning in 2002, all soybeans tested in the UW performance trials are analyzed for protein content.  Once a group of top performing soybean varieties is selected based on the previously mentioned traits, check to see if there are large differences in protein content and make a final decision based on grain quality.