NUE Explained: How NUE Impacts the Full Farm System

In this series, we’ve talked about what a Nutrient Use Efficiency score is and how growers can use their scores to improve farm finances. But how can understanding NUE impact growers’ approach to their full farm system? NUE is one piece of a complex puzzle that includes the soil microbiome, crop physiology and even weather, but when properly fit into a grower’s operation it can yield big benefits. 

Nitrogen receives a lot of attention when it comes to optimization, and for good reason — it’s a significant and often expensive input for growers, so any efficiency improvements can yield serious savings. However, by applying Nutrient Use Efficiency principles to other important macro- and micro-nutrients, growers have an opportunity to look closely at the whole farm system to improve crop health and yield. 

“By including nutrients beyond nitrogen, you can broaden NUE as a concept and really dive in,” says John Parrish, Senior Sales Agronomist with Sound. ​“Understanding NUE helps growers understand the principles of growing a crop, the soil interactions, even crop physiology better, and really drives those lessons home.” Take boron and nitrogen, for example.

Boron:

Studies have shown that an early application of boron during planting has the best chance to increase yield, and yet the highest uptake of boron in corn plants isn’t seen until V11. 

Maximizing NUE for boron means ​“we have to apply it at planting and hope it’s not going to leave the soil before the crop needs it,” says John. If boron is applied when uptake is greatest, the soil and plant systems can’t move the nutrient through the microbes and into the plant fast enough to improve yield. 

Nitrogen:

Unlike boron, nitrogen is not only prone to environmental loss, but it needs to be applied more or less when the plant needs it. For corn, between V10 and V14, nitrogen uptake is at its highest, although there’s still about a 10 day delay between application and availability to the plant. 

“A grower has to start understanding more about plant physiology and growth stages to be very meticulous about their nitrogen management,” says John. The goal is to hit the small window of opportunity when the crop hasn’t run out of nitrogen but will actually take up the nutrient from the soil. 

With an understanding of how key nutrients move through the soil system and enter the crop, growers can better decide which nutrients and products need to be applied, at what quantity and when in the plant’s growth cycle. 

“Understanding NUE goes further than just asking, ​‘What did I apply? What was my yield?’” says John. 

By paying attention to these whole system interactions, growers can start to improve management practices on a field-to-field basis. Even in neighboring fields, NUE can be completely different for each nutrient, so growers should look at each field’s specific needs. 

If dialing in NUE for all the macro- and micro-nutrients a plant needs on a field-by-field basis sounds impossible, that’s because it is. Even setting aside the time and effort required by the grower, all the interactions between plants, soils and nutrients aren’t fully understood yet. Instead, growers can focus on a few nutrients that soil testing and experience indicate will make the largest difference. By picking a field’s most limiting factors, growers will get the best chance to improve crop health and yield. Often, that list will include nitrogen for corn crops and phosphorus for soybeans. 

When growers do succeed at dialing in their NUE, though, there are big potential benefits not only to farm finances but to crop health and yield. And for John, the complexity of the process is part of what he loves about this industry.

“That makes it fun!” he laughs. ​“Just thinking about the different combinations and practices and applications that you can try, seeing that final yield result, and thinking, ​‘I can do it better next year,’ that really makes the job fun, even though it’s complicated.” 

When considering NUE on the full farm system, there are a few large-scale factors that can significantly affect a grower’s pursuit of better nutrient and input efficiency to improve yield and payout year to year.

“Weather plays a huge role in when and how the microbes in the soil begin to function,” says John. During an average weather season, growers will have a good idea of how the soil will behave, which nutrients will be mineralized and what will be lost to the environment, when rain can be expected, and when soil microbes will be dormant or active. 

“In Nebraska, we didn’t have a very cold winter this year and that allowed those microbes to continue to work, which allowed nitrogen to be lost, whether it was being used by those microbes or whether it was being leached or volitalized,” John says. Come spring, fall soil tests may not have been accurate, and growers could have been over-accounting for nitrogen in the soil and under-applying as a result. Conversely, a very hard freeze and little moisture in the spring could leave growers with more nitrogen than they usually account for, he explains.

While growers may not be able to change the weather, understanding how it impacts the system can help growers respond in calculated ways to maintain their efficiency and yield. 

Optimizing all nutrients on each field just isn’t doable, and applying inputs, studying field and crop results and examining what’s happening in the soil takes a significant amount of a grower’s time. Beginning with smaller-scale NUE goals can help growers set themselves up for success and expansion to other fields in the future. 

Most growers are already familiar with many of the complex interactions between their soil, their crop and the particulars of their region, from weather to equipment availability. Adding NUE into an already full workload can seem incredibly daunting, but the potential benefits are significant. 

“If you can get as close as you can to your optimal operation, your economics are going to be far better than they would be if you’re over-applying or under-applying nutrients,” says John.