University of Nebraska-Lincoln Extension, Institute of Agriculture and Natural Resources

March 31, 2006

Spring nitrogen management for winter wheat

Due to improved soil moisture across most of the major wheat growing regions in Nebraska, prospects for a good wheat crop have improved. (View seasonal precipitation data on the CropWatch Weather page.) With a more optimistic outlook but with higher nitrogen costs, many producers are asking about N management. Wheat stands across most parts of the state are good due to favorable conditions last fall and wheat prices have improved since last fall. Now is an excellent time to evaluate stands and check soil moisture to determine if additional N will be needed for higher yield potential. Additional acres of irrigated wheat have been added in some areas due to limited water. If only a portion of the N required was applied last fall, N needs to be applied soon. Many producers are applying most of their N in the spring.

Table 1. Nitrogen fertilizer recommendation for N at $0.45 per pound.
Residual nitrate
(ppm in a 3-foot sample)
Wheat price
$3.25/bu $3.75/bu
 
Lbs of N per acre
1
60
75
2
50
60
3
40
50
4
30
40
5
20
30
6
10
20
7
0
10
8
0
0
Spring nitrogen management

How much nitrogen do you need to apply this spring? Use soil test results for residual nitrate to a three-foot depth (taken now unless you have a soil test from last fall) and compare your numbers to those in Table 1 to determine recommended N rates. These rates reflect current prices for wheat and nitrogen calculated from the wheat N algorithm (Fertilizing Winter Wheat I: Nitrogen, Potassium and Micronutrients, G1460).

These recommendations are adequate for yields of 70 bu/ac or less. For irrigated wheat, the current guidelines suggest adding an additional 20 pounds of N to these recommendations. In most areas this may be sufficient, however, a better approximation would be to add 1.5-1.7 pounds of N per bushel above the 70 bu/ac yield level if you have consistently produced over 85 bu/ac. Remember, simply adding more N will not “enhance” yield potential. Many other production factors (seeding rate, variety, planting date, row spacing, irrigation timing and weed, disease and insect management) are controlling factors for consistently high yields.

Higher costs for dry or liquid N were used because ammonia is not commonly used for spring application. The higher N cost slightly decreases optimum N rates. Remember: Subtract any N applied last fall from these recommendations.

Nitrogen sources

Nitrogen solutions
Determining stand quality is equally important for weed control decisions which may be important when considering N fertilization. If nitrogen solution-herbicide combinations are used they need to be applied early for many broadleaf weed problems. Early N allows more time for distribution into the root zone but may be too early to control some weeds. Later applications may be optimum for some weeds but may cause problems with plant injury because of the herbicide-fertilizer combination.

Urea
Urea (46-0-0) is a good choice for spring topdressing if applied early. The cooler temperatures and the higher probability of precipitation helps assure a lower potential for N volatilization loss.

Gary W. Hergert
Extension Soils Specialist
Panhandle REC

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Copyright 2006 by the University of Nebraska Board of Regents. All rights reserved.
Published by University of Nebraska-Lincoln Extension in the Institute of Agriculture and Natural Resources Cooperating with the counties and the U.S. Department of Agriculture.
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