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

Objective

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.

Results

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
	LSD_0.05 = 17		LSD_0.05 = 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
	LSD_0.05 = 7	LSD_0.05 = 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
	LSD_0.05 = 10	LSD_0.05 = 9