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2006 Annual Report: Effect of Nitrogen Application Timing, Dry Sources and Rates on No-till Corn Yields


The supply of ammonium nitrate is decreasing and more urea production capacity is being built overseas. The goal is to determine the impact of changing nitrogen sources from ammonium nitrate to urea in NW Missouri.

Methods and Materials

Planting Date April 17 Herbicides PRE Glyphosate + Dual + Atrazine + Callisto; Post Accent + Clarity
Hybrid Pioneer 31G68 Insecticides Lorsban Banded 8oz/1000ft
Population 32,400 Row Width 30-inch

Ammonium nitrate, Urea and Urea + Agrotain was applied at March, April and May application dates and each with 5 different nitrogen application rates. The plots were established following a previous soybean crop.


There was no statistically significant difference between the application dates in 2006 and 2005. However, research indicates the nearer the time of application to the time when the corn crop will utilize it for growth, the less risk there is for loss.

Nitrogen Application Timing
2005 Application Dates Corn Yield (bu/a) 2006 Application Dates Corn Yield (bu/a)
16-Mar 191 24-Mar 179
2-Apr 190 24-Apr 181
19-May 195 23-May 186
  LSD0.05 = 17   LSD0.05 = 7

There was a statistically significant difference between ammonium nitrate and urea applied with Agrotain. However, research by Dr. Scharf, Extension Soil Fertility Associate Professor, would recommend the use of Agrotain with urea when top-dressed in no-till.

Dry Nitrogen Fertilizer Sources
Fertilizer Source 2005 Yield (bu/a) 2006 Yield (bu/a)
Ammonium Nitrate 194 186
ESN 192  
Urea 189 182
Urea + Agrotain   178
  LSD0.05 = 7 LSD0.05 = 7

Means with the same letter are not significantly different.

Effect of Nitrogen Rates on Corn Yield
Nitrogen Rates (lbs/a) 2005 Yields (bu/a) 2006 Yield (bu/a)
0 163 144
60 186 185
120 199 189
180 206 196
240 205 194
  LSD0.05 = 10 LSD0.05 = 9