NUE Explained: What Do You Do With a Bad NUE Score?

We’ve covered what an NUE score is, how to calculate yours, and how it can be used to improve farm finances and sustainability. But what are the first steps to take if your NUE score isn’t great?

With expertise provided by Zach Carlson, Agronomy Manager at Sound. 

What Is a Bad NUE Score?

As a rule, a lower NUE score is generally better because it represents a grower achieving more yield with less nutrient input. NUE will vary from farm to farm and field to field based on factors like soil characteristics, but how do you know when you should try and improve it?

Anything above 1.4 or even 1.2 should be evaluated,” says Zach Carlson, Agronomy Manager with Sound, adding that it’s not so much that the NUE score is bad” as it is unsustainable in the long term. With nitrogen prices still high and growing environmental concerns about volatilization and leaching, that kind of nitrogen to yield ratio is less than ideal.

What Causes a Bad NUE Score?

The first step to improving NUE is understanding what factors are having the biggest impact on efficiency. 

Soil characteristics such as organic matter content, pH and CEC may make it hard for soil to hold on to nutrients or create good mineralization, allowing applied nutrients to volatilize or leach out of the field. Weather can impact NUE as well, especially when paired with soils that struggle to hold on to nutrients. A particularly wet year can increase leaching and hot, windy conditions can increase volatilization. 

Sometimes with a high NUE score, it’s not necessarily that a grower is chasing high yields — it’s that they have to supply additional nitrogen because they can’t hold it in the soil,” says Zach. 

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The type of nitrogen fertilizer a grower uses can also increase environmental losses and impact a grower’s NUE score. Using the wrong type of nitrogen for your environment or soils could also be causing a high NUE.

Granular urea, as an example, is easy to apply, but is very unstable, especially in dry environments,” explains Zach. If it’s not transferred into the soil by moisture, it can sit there and volatilize really quickly.”

What To Do With a Bad NUE Score

Step one in addressing an unfavorable NUE score is identifying what is most impacting NUE; that will also be the key to unlocking strategies to improve efficiency. For example, if NUE is low because the soil isn’t holding enough of the nutrients the crop needs through the season, look at reducing nutrient loss and increasing the soil’s holding capacity. 

Growers should look at what kind of soil characteristics they have currently and see if there’s anything that they can do to increase organic matter, although it can take time to do so” says Zach. The higher the amount of organic matter in the soil, the more likely the soil can hold onto nutrients — not just N specifically, but nutrients as a whole.” 

Whether a grower’s farm is irrigated or dry farmed will also impact how they might address a high NUE score; on an irrigated farm, growers should consider whether reducing the amount of water applied to their fields will prevent some leaching. Making sure you’re using the right tillage practices for your operation can also minimize nutrient loss to leaching or volatilization.

Growers may find additional opportunities to improve NUE by evaluating their cropping choices. Depending on a grower’s particular operational needs, practices like cereal-legume intercropping, crop rotation or selecting more nutrient-efficient crop species may help improve nutrient efficiency. Cover crops may also add organic matter to the soil, increasing nutrient holding capacity.

“Farming is a very personal thing, but growers need to understand that they can move away from that high NUE score,” says Zach. “Ultimately the goal is to make small changes to achieve big results.”

The Importance of Strip Tests

One of the most important things a grower can do for themselves is implement small scale strip tests, especially when looking to improve their NUE score. That way, growers can test a new practice or product with less risk. 

Growers can give themselves a foundation of knowledge for their own farm by doing different kinds of strip tests with different products and practices,” Zach recommends. Farming is a slow process — you get one chance every year. But if you’re doing strip tests, you can condense that time on a smaller scale to figure out what is actually working.” 

Zach says growers who are unsure if certain practices or products will yield results on their operation should put in place protocols that are specific to their operation to prove to themselves that they can reduce nitrogen application on their farm.

Farming is a very personal thing, but growers need to understand that they can move away from that high NUE score,” says Zach. Ultimately the goal is to make small changes to achieve big results.”

Read more in our NUE Explained series