Nitrogen: sustainable considerations for yield, profit, and the environment

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As we think about farming and profitability, input costs are one of the most important pieces of the equation. Striking a management style that sustains yields, profits, and the environment are key considerations.

Nitrogen, which is used by growers to increase both yield and profitability, gets a lot of attention from both growers and the general public. There is a lot of buzz about nitrogen in the media, and most of it is not positive: nitrogen is present in surface runoff, well water and in lakes, leading to algae blooms. Nitrogen can also leach into groundwater supplies creating unhealthy nitrate levels in drinking water. These negative impacts of nitrogen can be mitigated through proper use to produce the food we all eat.

For wheat growers and consumers of end products – food – this increased crop yield means more flour, bread and pasta.

Even without knowing the facts about the necessity of nitrogen application to produce sufficient quantities of food, the public would be responsive to food produced with less nitrogen. Likewise, growers are the pioneers of conservation when it comes to this input, as they do not want to see their investment removed from the field from leaching or volatilization. It is simply good for the environment and business.

The primary question for growers is: should you do this by “using less” or by “increasing efficiency of use?”

The efficient use of nitrogen with an eye to using less

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Growers need to make use of this important fertilizer wisely, that’s the bottom line. Every part of ag needs nitrogen, it is one of the most important plant nutrients. For example, to produce wheat with high protein (which is in high consumer demand) there must first be enough nutrient resources (including nitrogen) to meet the plant’s requirements for growth and yield. Under fertilizing can cost you a great deal when it comes to high protein crops, so the factors and practices influencing protein content in wheat are critical. On the other hand, using too much fertilizer is detrimental to the input/output equation because of the high cost of nitrogen and potential negative environmental impact.

Using less fertilizer and increasing the efficiency of fertilizer use can be accomplished by leveraging the four “R”s: Right time, Right place, Right source and Right rate. Today, technology, knowledge, and research can help you manage the four Rs to increase the efficient use of nitrogen in growing wheat. For wheat growers, there are advances to help them know what form of nitrogen is needed, how much is needed (pounds per acre), and what application time in the growth season is best.

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Right Time

The timing of fertilizing wheat with nitrogen comes down to making applications either before the crop is planted, in-season, or both. For wheat, many growers apply in-season. At green-up, as weather begins to warm, plant tissue or soil samples can be taken and interpreted to provide a nitrogen recommendation.

Interpreting these results, the grower can apply nitrogen and other essential crop nutrients accordingly at the time they are needed and not risk front-loading large amounts of nitrogen in hopes that it is still there when the crop needs it. Waiting to collect soil samples or visually inspect plant growth and apply nitrogen only as needed results in more efficient use of fertilizer, saving money and increasing profits.

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Right Place

For wheat, most growers top-dress during the growing season. There are technologies such as seeds treated with coatings that help the plants use nutrients such as top-dress applied nitrogen more efficiently while increasing yield.

One such coating uses microbes that make it possible for plants to take up and use nutrients like nitrogen more easily and efficiently. This translates to the use of less nitrogen and increased profitability. Seeds with a microbial coating have been shown to increase crop yield.

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Right Source

For wheat applications, nitrogen usually is applied in the form of 28%, 32%, and urea. Most nitrogen used on wheat in the U.S. is 28%. Urea is the cheapest source, but not the most effective. Urea can partially volatize during top dressing especially during sunny days.

If there is excess water (from rain or irrigation) it can potentially leach out into groundwater or runoff into surface water. Therefore the nitrogen is both unavailable to the plant and contributes to the “nitrogen in our water supply” problem. Adding nitrogen stabilizers to urea and UAN are additional ways to protect your investment and keep it where you want it thereby reducing the negative impact to the environment and profitability.

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Right Rate

Wheat growers used to operate on blanket assumptions about how many pounds of nitrogen were needed for a field, leading them to treat all their fields the same. Today growers can send plant tissue or soil samples to a lab and get back results showing the current nitrate content. The lab analysis can guide growers to make the appropriate nitrogen application to specific fields.

If growers sample plants or soil from different fields, the fields with lower concentrations of nitrogen will need more nitrogen applied to them. Conversely, those with higher concentrations will need less or none. If this more efficient (and profitable) use of nitrogen through sampling were more broadly used, it could help counter the negative public perception. 

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Data analysis, the next step after collection, turns the information into an actionable recommendation for the grower. Once you know the nitrogen status of your individual fields, you know exactly what steps, if any, to take to improve the situation.

There’s no reason why a grower must decide in isolation. Growers can work with agronomists to share data and utilize the agronomists’ plant fertility expertise to develop action plans and make more informed decisions. With the right guidance, instead of applying more nitrogen to a yellow field, you might conduct tissue or soil sampling and get advice from an agronomist on how to adjust the rate of nitrogen for both this and next year’s crop. Agronomists have the advantage of working with you over time, sometimes from year-to-year, developing strong knowledge of your fields. They also have the advantage of working with many growers, giving them a broader perspective.

Conclusion: A fifth R?

Wheat is not a legume crop with nodules like soybeans which can fixate nitrogen; wheat is a monocot, a grass crop which cannot fix nitrogen. Wheat needs all the help it can get to make the most of nutrients like nitrogen. Success with the 4Rs produces the high protein crop that brings a premium in the marketplace. An important “Right” here is a fifth one: starting with the right seed, the kind coated with microbes to help wheat plants make better use of nutrients like nitrogen. The microbes help plants bring nutrients into the plant. In the end this would mean proper nutrition for the plants, higher yields, greater profitability for growers and less money spent on fertilizer; all in an environmentally sustainable manner.

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