Make spring N application in wheat or not?
click image to zoomFigure 1. Percent of normal precipitation for the last 180 days (as of April 6, 2012). With windy, dry conditions in many of Nebraska’s wheat growing areas, some producers are asking whether it would be profitable to add nitrogen this spring.
Many areas received little moisture this winter and early spring (Figure 2), have no snow cover, and were hit by several days of strong winds this spring.
Even though we had great stands last fall, Extension crops specialist Drew Lyon notes that dry areas are beginning to appear in the Panhandle and southwestern Nebraska.
Wheat prices are good, but fertilizer N prices are high and continue to climb. If you did not book your fertilizer supplies earlier, you will pay a premium this spring.
What are the odds that N application will be profitable this year? The lack of moisture this winter should have limited any loss of N from leaching or denitrification. The N you applied last summer and/or fall is still there, just waiting for the crop to begin growing.
To help determine the potential profitability of a nitrogen application for your operation, use Table 1 as a guide.
The N price is set at $0.70 which is in the range of current prices for N from urea or UAN solution. Nitrogen rates should be based on soil tests for residual nitrate to a three-foot depth, however, if you do not have a soil sample, use a base level of 6 ppm nitrate-N for wheat planted after fallow and 4 ppm for wheat planted after an adequately fertilized previous crop (shaded area in Table 1).
If you decide to apply N, you may want to apply it soon, before wheat reaches the jointing stage. With the warmer and drier than normal conditions this spring, wheat development is about two weeks ahead of normal.
Producers should also consider the chance for precipitation to incorporate applied N. If more than 75 percent of your total N was applied last fall, additional N may not provide additional yield if precipitation is limited. If stored soil moisture at planting was excellent, some rain will produce a good but not great crop. click image to zoom
It is still early in the year and a wet April and May could make a huge difference. Long-range forecasts for the central plains, however, are not encouraging. With 50 lb of N at $0.70, you will need a 6 bu/ac yield increase to pay for the fertilizer at $6.00 wheat. Yield increases for wheat with low soil nitrate should be in the 10 to 12 bu/ac range.
Applying N to dry, cool soils reduces the potential for N volatilization losses from urea-based fertilizer (urea and UAN solution). With warm but dry conditions, there should still be limited potential for N volatilization. If N must be applied to moist soils, consider using a urease inhibitor. Potential N losses (usually less than 10-15%) must be weighed against the additional cost of the inhibitor.