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PFR Report: 2017-2018 Nitrogen Rate Results on Wheat

Published on Wednesday, July 11, 2018

As farmers, we do our best to create an environment that encourages positive plant responses like higher yields. For example, we may alter the environment by planting a different population, utilizing a new method of working soil or, perhaps the most obvious, adding a fertilizer. All of this is done in the hopes that the plant’s response, or its phenotypic alteration in response to its environment, creates additional yield and profit.

In wheat production, fertilizer rate is critical for maximizing yield, particularly in a nitrogen (N) application. Applying N to wheat can be one of the most difficult decisions to make in the spring because a plants response to N can vary greatly due to weather and a variety of other factors. Over the past seven years, Beck’s PFR has evaluated how different N rates impact wheat yields. This year, the study was conducted at four PFR locations: Indiana, Kentucky, Ohio and Southern Illinois. The goal of this study was to determine the wheat Economic Optimum Nitrogen Rate (EONR), or the nitrogen rate that maximized profitability per acre.

When aiming for 90 to 100 Bu./A. wheat, the question is not “should I apply N?” but rather “how much N should I apply?” Too much N can contribute to a higher potential for root lodging. While N helps the plant develop great grain fill, unfortunately sometimes the plant can become too top-heavy causing the head to bend to the ground on a fragile stem. However, too little N can result in lost yield potential. Finding the balance between the two is critical to a healthy wheat crop.

For this year’s N rate study, each PFR location used a population of 1,500,000 seeds/A. Spring nitrogen applications began at 40 units and increased by intervals of 20 units, topping out at 140 units. In total, six different treatment levels were studied. The Indiana and Ohio locations applied nitrogen at Feekes 3, while Kentucky and Southern Illinois applied a split application at Feekes 3 and Feekes 5.

Nitrogen is most commonly applied at Feekes 3 or with a split application at Feekes 3 and 5. These are the most optimum stages for an application because N is made available to the plant soon after it breaks dormancy. This is also when tillering is established and the plant prepares to begin its rapid vertical growth stage, or in a split application, the rapid growth stage. This year, Beck’s PFR team observed that the return on investment (ROI) starts to decrease soon after receiving 80 units of N, regardless of how it was applied.

Each year, the optimum N rate needed for wheat to reach 100 Bu./A. varies. This season, Beck’s PFR data revealed that 80 units of N offered the largest ROI and was the EONR because it offered the most profitability per acre. Although the 100-unit application yielded the highest, the gain from the yield less effectively offset the cost of the N when compared to the 80-unit treatment in both the Feekes 3 and split applications.

Through our seven-year, multi-location data, we have identified three EONR’s based on the price per unit of N.

As you consider N applications on your wheat fields for future crops, it’s important to make sure you have sturdy genetics accompanying your applications to ensure you’re on the path to your greatest ROI potential.


A big thanks to our PFR Intern, Sarah Harden, and Marketing Intern, Michaela Kramer, for their contributions to this article. 


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Jim Schwartz

Jim Schwartz

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