March 28, 2013

Figure 1. Percent of normal precipitation for the last 180 days as of March 21, 2013 (top) and April 1, 2012 (bottom).

Spring fertilizer management for 2013 wheat presents bigger challenges than last year due to the continuing drought (Figure 1.

Limited winter and early spring precipitation in western wheat-growing areas, the lack of snow cover, and several days of strong winds in March have producers wondering if and when they should apply nitrogen this spring (Figures 2 and 3). Producers east of North Platte have had more winter precipitation. Now that wheat has broken dormancy, they can evaluate stand, weed pressure, and soil moisture conditions. The March 22 CropWatch featured an excellent guide to checking the current crop

Once you determine yield potential, use that number to guide your final fertilizer decision, adjusting the nitrogen recommendation based on this year’s potential yield versus your long-term average.

Wheat prices are slightly higher than a year ago while fertilizer N prices are similar to last year and don’t appear to be increasing. What are the odds that N application will be profitable this year?

Soil tests from many areas show significantly higher nitrate-N carryover (see March 6 CropWatch article). The lack of moisture this winter should have limited any loss of N from leaching or denitrification. The N that was applied last summer and/or fall is most likely still there, just waiting for the crop to begin growing. Several producers have reported that they have resampled this spring and found higher levels and will use that information plus stand to determine a final N rate. Wheat growth ranges from tillering (stage 3 to 4) in eastern Nebraska to just breaking dormancy in western Nebraska.

Use Table 1 as a guide for adding N this spring. 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). With drier and cooler conditions this year, wheat development is about normal, so you still have time to apply N before wheat reaches the jointing stage.

See the UNL publication, Fertilizing Winter Wheat (EC 143), for N recommendations.

Gary Hergert, Charles Wortmann, Richard Ferguson, Charles Shapiro and Tim Shaver
Extension Soils Specialists