Nitrogen fertilizer costs continue to be one of the most expensive variable production
costs for corn. Applying “more than enough N” is no longer cheap “insurance” as it once
was many years ago. Applying “more than enough N” is also not environmentally
friendly. High N fertilizer costs and environmental impacts should encourage growers to
critically evaluate their N management program, including application rate, fertilizer
material, and timing.
Nitrogen rate recommendations for a given field were traditionally linked to its historical
yield levels (Camberato, 2012). For corn/soybean, the traditional rule of thumb was an N
rate equal to about 1 lb of N per bushel of expected yield. For corn following either corn
or wheat, the recommendation was equal to about 1.2 lbs of N per bushel.