Agronomist: Early Signs of Crop Stress to Watch for When Scouting for Nutrient Deficiencies

Roland Leatherwood with The Mosaic Company discusses field scouting, nutrient deficiency detection, tissue sampling, and in-season nutrient management amid high fertilizer prices.

Tractor spray fertilizer on green field drone high angle view, agriculture background concept_Photo by Mose Schneider via AdobeStock_357547735.jpg

Photo by Mose Schneider via Adobe Stock

RALEIGH, N.C. (RFD NEWS) — As the growing season advances, many farmers are scouting fields for early signs of nutrient deficiencies.

Roland Leatherwood, agronomist with The Mosaic Company, joined us on Monday’s Market Day Report to discuss the importance of field scouting and in-season nutrient management.

In his interview with RFD News, Leatherwood discussed why it is critical for growers to be out scouting their fields early in the growing season and the role early observations can play in identifying potential issues before they become more severe.

“You put it very well: What it is, is that in-season nutrient deficiencies will lead to lower yields,” Leatherwood told RFD News. “Recognizing the signs of nutrient deficiencies early can help farmers make a plan to address those deficiencies, whether we top-dress or side-dress applications, and protect yield potential for future seasons as well.”

He also detailed early warning signs of nutrient deficiencies in crops, what growers should watch for as crops continue to develop, and what amendments are needed:

  • “With nitrogen, you’ll first see yellowing lower leaves; it often begins in corn as a V-shape. With other crops, you’ll get stunted or slow plant growth. That yellowing eventually becomes browning, and you get death of the older leaves.
  • “For phosphorus, you’ll get a purplish discoloration on older leaves or a much darker green. Plant stems will be stunted in appearance, and eventually you’ll see browning and death of leaf tips, delayed maturity, and small crop leaves.
  • “The story on potassium is you get yellowing, or leaf burn on the edges, maybe small white or yellow spots along the edge, and reduced stalk strength. Potassium is important to manage stress and lodging as well.
  • “And finally, don’t forget about sulfur. It’s one we don’t often think about, but you’ll get yellowing first, starting in older leaves. Eventually, the whole plant becomes light green in color, initially on younger leaves, but then it leads to the whole plant.”

Leatherwood emphasized how tissue sampling can help confirm what growers are seeing in the field and how that information can guide management decisions.

“If you’ve seen a problem, you can use tissue sampling to correctly diagnose the deficiency,” he explained. “Tissue samples give you a snapshot within the season of what’s going on in the moment. The way you manage that is by simply pulling your tissue samples—whether they’re leaves or whatever you’re doing—from your problem area and from a good area. So remember, you’ve got to have them in pairs, and then send those off to your favorite lab. That will support your visual observations in the field, and depending on the report you get back, help you quantify how to correct it.”

He also outlined options available to growers if nutrient deficiencies are identified, including approaches that can be implemented during the growing season to address those issues.

“Well, if it’s early enough in the season, there’s still time to top-dress or side-dress to provide the nutrients they are missing and rescue yield potential,” Leatherwood noted. “Another good option is to apply crop nutrition products like BioPath that can help maximize nutrient use efficiency early in the season and strengthen return on fertilizer investment.”

Looking ahead, Leatherwood shared his outlook for the growing season and offered final advice for farmers as they continue monitoring crop development.

LEARN MORE: The Mosaic Company

Marion is a digital content manager for RFD News and FarmHER + RanchHER. She started working for Rural Media Group in May 2022, bringing a decade of digital experience in broadcast media and some cooking experience to the team.

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