Economize by reducing N rate, according to U
Written by Jonathan Eisenthal
In recent years, the ratio of nitrogen fertilizer price to corn price has been approximately 0.10, which is the equivalent of $0.40 per lb. nitrogen and $4.00 per bushel corn. Currently it’s running as high as $0.80 cents per pound with corn still at $4.00 dollars—a 0.20 ratio.
One place to turn, according to Brad Carlson, a fertilizer expert with University of Minnesota Extension, is the University of Minnesota nitrogen rate recommendations, geared to the economics of both corn and fertilizer, to find the Maximum Return to Nitrogen (MRTN).
“We are currently experiencing historically high price ratios between the price of nitrogen and the price of corn,” Carlson said. He noted that University of Minnesota Extension has measured MRTN this way since 2005. “In twenty years, this is the highest price ratio we’ve ever experienced.”
The University conducts rate research regularly that shows how the yield grows dramatically through the initial increases in nitrogen rate, but starting around 120 pounds per acre, the yield increase slows, and as the rate goes higher the curve flattens, until the increase in bushels pays less than the extra nitrogen needed to get them. Finding the point at which additional N fertilizer no longer increases yield at a level that pays for itself can save operators dollars per acre.
Carlson said two other considerations could lead to cost savings on fertilizer. First, the form of nitrogen affects the price. Anhydrous Ammonia is the initial form of all artificial fertilizer and is thus the most economical. Ammonia must be further processed to create Urea and other forms of nitrogen fertilizer, thus there is added processing expense priced into them. One problem with sourcing Ammonia, Carlson noted, is that, due to the hazards associated with handling it, many dealers no longer offer it.
Ammonia is the most stable form of nitrogen, once it’s applied, Carlson reported, which is why it’s the form recommended for fall applied nitrogen in most of the state. Unfortunately, Ammonia can’t be obtained everywhere. It is more readily available in southern Minnesota than in western and central Minnesota, he said. A third consideration is to lower or forgo the application of the other key macronutrients, Phosphate and Potassium if the soil test is at a medium level or higher. Many farmers routinely apply a replacement rate of these two nutrients regardless of soil test. In a year like this where the cost of fertilizer is high, and profitability is low, farmers with adequate Phosphate and Potassium can skip the application without an immediate impact on yield, and resume applying these nutrients when a higher corn price supports it.
