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Fluid Journal : Fall 2012
Fall 2012 The Fluid Journal 02 Summary: The popularity of urea-ammonium nitrate solution (UAN) in the U.S. has increased steadily and substantially over the past 50 years. While direct- applied anhydrous ammonia dominated the overall U.S. nitrogen (N) marketplace through the 1980s, UAN and anhydrous ammonia have each had about the same market share (nutrient basis) in the U.S. over the past decade (Figure 1). While UAN consumption is not as high in other places across the globe as in North America, the global popularity of UAN continues to increase, especially in Europe and the former Soviet Union. Adaptability and Flexibility! The Fluid Journal • Ofﬁcial Journal of the Fluid Fertilizer Foundation • Fall 2012 • Vol. 20, No. 4, Issue# 78 Dr. Dale F. Leikam Why UAN Solution? Uan is a non-pressure N solution primarily manufactured by combining urea liquor, ammonium nitrate liquor and water in large production plants. In addition, a small amount of ammonia (to neutralize acidic pH) or other corrosion inhibitor is added to reduce the corrosivity of the product. As manufactured, UAN can be safely and easily stored, handled, and applied with mild steel equipment and storage. UAN is based on the principle that mixtures of urea and ammonium nitrate are more soluble, and provide for a higher N analysis than either urea or ammonium nitrate by themselves. These types of solutions are termed 'eutectic solutions' and the specific ratio of salts at which maximum solubility exists is termed the 'eutectic point' . This principle is presented in Figure 2 for urea and ammonium nitrate solutions. Note that if only urea or only ammonium nitrate were used to make N solutions, the resulting product would only contain about 19 percent N with a salt-out temperature of 32oF. However, if the N solution is comprised of about 35 percent urea, 0% 5% 10% 15% 20% 25% 30% 35% 40% 45% 1960 1970 1980 1990 2000 2010 Percent of Totan N Consumpton Figure 1. U.S. N Product Marketshare 1960-2010 Anhydrous UAN Soluton Urea Source: USDA Economic Research Service
Late Spring 2012