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bioweb.sungrant.org » Technical » Biomass Resources » Agricultural Resources » Existing Crops » Soybeans

Soybeans	Printer Friendly

On average, around 73 million acres of soybean (Glycine max) are harvested annually in the U.S. although acres vary by year. Average national soybean yields have ranged from 38 to 43 bu/ac between 2000 and 2006, mostly due to weather (table 1). Production is concentrated in the Midwest (about 70% of the harvested acres are in the states of Illinois, Indiana, Iowa, Minnesota, Missouri, Nebraska, South Dakota, and Ohio), but occurs throughout much of the U.S. (USDA-NASS) (figure 1). Currently, about 84% of soybean acres are produced in rotation with another crop, typically corn (about 75%), although other crops (e.g., wheat, rye, barley, and oats) are also used (Kim and Quimby, 2003; USDA-ERS, 2006). Soybean is sometimes double cropped (two crops in the same season on the same acres) in areas where weather permits (such as the south), most commonly with winter wheat (USDA-ERS). Conservation tillage is used more widely in soybean production than with any other major crop. At a national level, 43% of soybean acres used conventional till operations, 24% used reduced till operations, and 33% employed no-till methods in 2000 (Conservation Technology Information Center, 2000).                                            Soybean is typically planted in 30 inch wide rows at a rate that yields 140,000 plants/acre (ISU, 2000). In the Midwest, it is typically planted in May and June and harvested in October. The production of new semi-dwarf varieties on good soils show higher yields when planted between May 1-15 in densely pack rows (7 inches wide, 300,000 plants/acre) (Comis, 2001).   Soybean fixes nitrogen so nitrogen fertilization is much lower for soybean than for many other crops. National average fertilizer rates in 2004 were 28 lbs nitrogen/ac (range of 10 to 42 lb N/ac; applied on 21% of planted acres), 69 lbs P2O5/ac (range of 48 to 90 lbs P2O5/ac; applied on 26% of acres), and 121 lbs K2O/ac (range of 36 to 164 lbs K2O/ac; applied on 23% of acres) (USDA ERS). Pesticide use increased from 83.5 million pounds to 87.8 million pounds active ingredient between 1997 and 2004, although herbicide use declined in part due to the shift to herbicide tolerant varieties (used on 80% of soybean acres) (Osteen, 2006, Kim, 2006).   The estimated costs of producing soybeans vary by region ranging from $213.45/ac to $280.44/ac in 2005 (Ash, 2006).    In the U.S., soybean is produced primarily for livestock feed. About 30-35% of raw soybean is exported with the remainder used domestically. The soybean is crushed to obtain soybean meal and soybean oil. Soybean meal is fed to livestock (50% for poultry feed, 26% for swine, 12% for beef, and the rest for other animals). Around 7 million tons of soybean meal is exported.   Soybean oil is used mainly for food uses although about 4 percent (628 million pounds) of the soybean oil produced in 2004 was used to produce bioproducts (such as inks, adhesives and binders, and used in plastics and detergents among others). In 2004, 30 million gallons of biodiesel was produced from soybean using about 20 million of the 1.65 billion bushels produced (SoyStats, 2005). Biodiesel production in 2005 was 66 million gallons (92% from soybean oil) (Ash, 2006).   On average, soybean contains about 35% protein, 18.5% oil, and 5% fiber and a bushel of soybean yields about 11 lbs of oil and 48 lbs of soybean meal (44% protein) although variations occur based on variety and climate conditions among other factors (Maier, 1998; USB, 2003).   The soybean varieties currently planted produce only limited quantities of stubble (the above ground, non-grain portion of the soybean plant), and after leaving sufficient quantities of residue on the fields to maintain soil quality and productivity, little stubble is left to be collected and used as a bioenergy and bioproduct feedstock.  However, one study (Perlack, 2005) suggests that soybean varieties with simultaneously higher seed yields and higher residue production than current varieties could potentially be produced so that soybean stubble might become a potential feedstock in the future.   Soybean production has steadily increased over time, from 1.13 billion bushels in 1970 to 3.09 billion bushels in 2005. Much of this increase has been due to increases in acres (from 42.25 million harvested acres in 1970 to 71.36 million harvested acres in 2005), however average national yields have increased from 28 bu/ac during the 1970’s to 39 bu/ac between 2000 and 2006.   Soybean yields are expected to increase slightly in the near term. The USDA projects average national soybean yields of 44.3 bu/ac and 69.4 million harvested acres by 2015 (USDA OCE). FAPRI projects average national soybean yields of 43.9 bu/ac and 68.9 million harvested acres by 2015 (FAPRI, 2006). A workshop of crop experts (English, 1997) projected that under the mostly likely scenario, average national soybean yields of 60 and 70 bu/ac could be achieved by 2030 and 2050 respectively (compared to 1990-1992 yields of 35 bu/ac) resulting from genetic, management, and equipment improvements.    While research to increase soybean yields continues, research to develop new varieties with traits more conducive to its use for bioenergy and bioproducts is also underway. Approaches include increasing the oil content of soybean. High oleic acid varieties of soybeans are also being developed—high oleic acid content increases the oxidative stability of soy oils and improves their use for lubricants and greases (Pioneer, 2006).

References
Don Comis, Pushing the Yield Limits, Agricultural Research, June 2001. B.C. English, R.L. White, and L. Chuang, Crop and Livestock Technologies, RCA III Symposium, Iowa State University Press, Ames, IA, 1997. Food and Agricultural Policy Research Institute (FAPRI) (January 2006), FAPRI 2006 U.S. and world agricultural outlook, Iowa State University and the University of Missouri-Columbia, FAPRI Staff Report 06-FSR 1. C.S. Kim and William Quimby, ARMS Data Highlight Trends in Cropping Practices, Amber Waves, U.S. Department of Agriculture, Economic Research Service, February 2003. Iowa State University, University Extension, Soybean Replant Decisions, PM 1851, June 2000. Dirk E. Maier, Jason Reising, Jenni L. Briggs, Kelly M. Day and Ellsworth P. Christmas, High Value Soybean Composition, Purdue University, November 23, 1998. Osteen, Craig and Michael Livingston, Pest Management Practices, Agricultural Resources and Environmental Indicators, 2006 Edition, Keith Wiebe and Noel Gollehon (editors), U.S. Department of Agriculture, Economic Research Service, Economic Information Bulletin No. EIB-16, July 2006. Robert D. Perlack, Lynn L. Wright, Anthony F. Turhollow, Robin L. Graham, Bryce J. Stokes, and Donald C. Erbach (April 2005), Biomass as feedstocks for a bioenergy and bioproducts industry: the technical feasibility of a billion-ton annual supply, ORNL/TM-2005/66. Pioneer Seed Company, Crop Insights, Biodiesel Production in the U.S., vol. 16, no. 5, 2006, www.pioneer.com. SoyStats Online, Syngenta Corporation, www.soystats.com/2005. Mark Ash, Janet Livezey, and Erik Dohlman, Soybean Backgrounder,           U.S. Department of Agriculture, Economic Research Service, OCS-2006-01, April 2006. U.S. Department of Agriculture, Economic Research Service, Data Sets, U.S. Fertilizer Use and Price, www.ers.usda.gov. U.S. Department of Agriculture, Office of the Chief Economist, USDA agricultural baseline projects to 2015, Baseline Report OCE-2006-1, February 2006. United Soybean Board/American Soybean Association 2003 Soybean Quality Survey Data.