It won’t be long until the snow starts melting off, and things will start greening up again. For those who raise wheat, applying nitrogen is one of the first agronomic activities of the year. In fact, some people get a little antsy and put fertilizer on wheat a little too early in the spring.
Nitrogen applied too early (before “green-up”) in the year can promote excessive vegetative growth. The plants will look really green, and really full, but looks do not always translate into a profitable yield. If this early growth is followed by prolonged cold weather, damage can occur that reduces yield.
The ideal timing for a nitrogen application is between spring green-up and jointing (the first visible stem elongation). This is not only healthier for the plant, but is also the most profitable time to apply the nitrogen, because the plant uses the fertilizer very effectively at that stage. After the flag leaf forms on the wheat, the yield response to a nitrogen application is minimal.
The rate to apply nitrogen in the spring depends on your yield goal, and whether you applied any nitrogen at planting time. The formula works like this: If your yield goal is 80 bushels of wheat per acre, subtract 50, and then multiple the remainder (30) by 1.75. Your answer should be 52.5. Now add 40. Your answer is 92.5, which is the recommended pounds of nitrogen to apply to the wheat over the course of the season. If you applied 30 pounds of nitrogen in the fall, then you should plan to apply an additional 60 pounds of nitrogen this spring.
Using that same formula, a person shooting for 100 bushels of wheat should be applying approximately 130 pounds of nitrogen during the season.
For top dress applications containing urea, consider using a urease inhibitor if the weather conditions favor volatilization (wet, warm and windy, but not raining). When UAN is used as a nitrogen source, you can often see foliar damage on the wheat. Stream bars can be used to reduce this damage, but the research results show little yield advantage compared to using flat fan nozzles.
Being patient and waiting for “green-up” to apply nitrogen to wheat can be difficult after a snow-filled winter. However, waiting for “green-up” will give you a better chance to maximize profitability.
Jeff Burbrink is an Elkhart County Extension educator for Purdue University.