NUE Explained: How Does SOURCE Impact NUE?

In our NUE Explained series, we’ve dived deep into what it is, how it impacts the whole farm system, and what NUE means for sustainability. Now, we’re digging in to how growers can use SOURCE, Sound’s microbiome activator, to help them improve their NUE score. 

With expertise provided by Jenna Stonehocker, Sales Agronomist at Sound.

A Nutrient Use Efficiency (NUE) score is a way to capture the relationship between how much of a particular nutrient is applied and yield. NUE offers growers an opportunity to understand how well the nutrients they apply are being used by the crop. Although NUE is often used in reference to nitrogen application, applying NUE principles to other micro- and macro-nutrients allows growers to improve their overall efficiency. 

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NUE is a simple ratio of pounds of nutrient applied to bushels of yield.

For NUE, a lower number represents higher efficiency, or a smaller amount of an input like nitrogen fertilizer required per bushel. Growers who want to improve their NUE score must look for ways to reduce inputs while maintaining or boosting yield.

What is SOURCE?

Nutrients like nitrogen and phosphorus often exist in forms that plants aren’t able to access; phosphorus tied up in the soil with other minerals and nitrogen as atmospheric nitrogen gas. Growers apply synthetic versions of these nutrients to their soil, but they are prone to atmospheric loss, leaching, and tie up. 

Sound’s flagship product, SOURCE, is a molecule that mimics the plant-to-microbe signal to boost the nitrogen fixing and phosphorus solubilizing microbes already in a grower’s soil in order to increase in-season access to plant-available forms of these nutrients. 

SOURCE provides 25 pounds of nitrogen and 25 pounds of phosphorus in a non-synthetic form,” says Jenna Stonehocker, Sales Agronomist at Sound. That means the nutrients are coming from microbes in the soil, not fertilizer inputs.”

Soil Health and NUE

Whether or not growers seek to improve soil health to boost NUE or for broader benefits, healthy soils play an important role in improving on-farm efficiency.

Jenna, who is based in Kansas, says many of the growers she works with are interested in improving their soil health. They have adopted practices like cover cropping or no-till, well-known practices that are good for the soil,” she explains. 

In particular, these practices can help increase the organic matter in soils, which both improves soil characteristics like water holding capacity and structure and provides a source of macro- and micro-nutrients to crops. To access those nutrients, however, crops rely on soil microbes to digest, break down, or convert organic matter into nutrient forms that plants can use. 

SOURCE is activating those microbes already in a grower’s soil to provide access to those nutrients,” says Jenna. It’s not a fertilizer; it leverages the natural relationship between plants and soil microbes to provide a more efficient nutrient option for the crop.”

Improving nutrient use efficiency increases a grower's ROI by reducing input costs while maintaining or increasing yield.


NUE represents a way for growers to examine input costs compared to yield and cut back on expensive nutrient applications. Using SOURCE and reducing fertilizer input has a direct impact on a grower’s NUE by allowing them to reduce nitrogen and phosphorus inputs without sacrificing yield. But however improved operational efficiency and NUE are achieved, reducing inputs while maintaining or boosting yield has a direct impact on a grower’s ROI, and for Jenna, that’s the bottom line. 

It’s well known that the last pounds of nitrogen are the most expensive — or any nutrient, really,” she says. The return on investment for those last pounds is significantly diminished because it’s so hard to provide only what the plants need, but no more. Those excess pounds become increasingly expensive when you compare how much you’re applying to how much yield you get back.” 

The ROI for those last pounds is significantly diminished because it’s so hard to provide only what the plants need, but no more.

Because so many of those expensive last pounds of nitrogen won’t directly boost yield, cutting back or eliminating them can have a big effect on a grower’s NUE and farm finances. Finding the sweet spot between over and under applying can be challenging, and that’s where SOURCE shines. 

One way growers can use SOURCE is to add it to their fields when they’re not sure they have quite as much nitrogen or phosphorus as they need, instead of applying fertilizers and getting diminishing returns,” says Jenna. It can help to fill the nutrient gap at a much lower cost than normal fertilizer.”

SOURCE can be added to herbicide or fungicide tank mixes for easy foliar application.

SOURCE can also help growers make sure the crop can access the nutrients they’ve already applied, she points out. Phosphorus that you’ve already paid for and applied might not actually be getting into the plant in time, because it’s so prone to being locked up in the soil,” she explains. By boosting phosphorus solubilizing microbes in the soil, SOURCE can help growers make sure their crop has access when they need it.”

Additionally, SOURCE is easy and inexpensive to use. It can simply be added to a grower’s tank mix for easy application, no extra passes or added fuel costs necessary. SOURCE also has a low use rate, so a little goes a long way, and its wide application window offers growers flexibility and convenience.

In the agriculture industry, practices and products must produce a good ROI in order to drive change,” says Jenna. Growers have to make choices based on what is a good fit for their farm, and SOURCE makes financial sense.”

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Ready to learn more about SOURCE?

SOURCE improves nutrient availability to your crops by stimulating nitrogen fixing and phosphorus solubilizing microbes. The result is more macro and micronutrient availability leading to healthier, more productive plants. A foliar application of SOURCE provides 25 pounds of nitrogen and phosphorus per acre.