Macro and Micronutrient Deficiencies To Watch For

With 45,000 tissue samples analyzed in 2019, WinField United is working use the 600,000 data points generated in the program. The end goal: understand and tighten the relationships between soil tests, tissue samples, field history, crop modeling and yield. 

“We want to refine the in-season management of crop nutrients because that not only can drive better yields but also sustainability,” says WinField United agronomist Jon Zuk. “Sometimes we have to use what we learned last year and apply it to the next year—so it’s a report card.”

Zuk says the key takeaways from the yearly program are available because of the mass of data and geographic diversity—it helps illuminate areas where any grower may look to find opportunity for better management and improved yields. 

Takeaways include: 
More than 80% of the corn samples show zinc deficiency.  

“This is the No. 1 or No. 2 deficient nutrient overall. Zinc in the plant is immobile, so in order to get zinc sufficient in the plant when it needs, you have to have a multiple approach to your zinc strategy. One product is never going to fix a zinc problem,” Zuk says. 

Zuk says zinc can be a tough one to crack, partially because everyone can find success with a totally different strategy. Tissue testing has shown that timing is key. 

“V5 to V9 is the sweet spot,” he says.

Sulfur is a mobile nutrient but it’s not being managed that way. 

“Farmers should be applying sulfur like they do nitrogen,” Zuk says. “Agronomists who make tidier recommendations are able to dial in sulfur and make nitrogen more efficient. When sulfur is never deficient, you don’t have to apply as much nitrogen. Put sulfur down with your nitrogen, it’s a good place to start.”

Boron, Manganese and Nitrogen were also deficient in a majority of the corn tissue samples. 

“In 2019, we had 50+ inches of rainfall in my area. That moved a lot of nitrogen,” Zuk says. 

He also explains that since 2013, the tissue tests have shown that the percent nitrogen deficient is an indicator of how much rain had fallen that year. 

“What we can say about 2020, we have full soil profiles. Any rainfall we get, we’ll get a similar trend as 2019,” he says. “Manage nitrogen accordingly—do split applications, know what form of nitrogen you are applying, use a stabilizer.”

As for opportunities to avoid the common micronutrient deficiencies, he says it’s all about timing. 

“At V10, there’s a good time to correct for manganese,” Zuk explains. “Looking at 39,000 tissue samples, I see boron flash the most deficient at two weeks before tassel. So right before tassel, I see a sweet spot for application.”

Potassium was deficient in 75% of soybean samples.  

“Potassium brings all the nutrients in the plant, so if we are deficient in potassium, everything else we do is inefficient,” Zuk says. 

He’s encouraging farmers to rethink their fertilizer applications.

“The only way to get potassium in the plant is to put fertilizer on ahead of soybeans,” he says. “And when the grower gets in the mindset of managing the acre every year, you can easily manage swing acres.” 

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