By Matt Hutcheson, CCA, Product Manager, Seed Consultants, Inc.
Due to heavy rainfall and saturated soils during the 2019 growing season, it is not surprising to see some signs of nitrogen deficiency showing up in corn fields across the eastern Corn Belt. Whether applied preplant or sidedress, patterns of heavy rainfall and wet soils increase the likelihood of nitrogen being lost. Because nitrogen is an essential nutrient for corn plant development and ultimately yield, losses will impact final yields this fall.
When saturated conditions persist, nitrogen can be lost though leaching or denitrification. Leaching (more likely to occur in course-textured soils) is the process where nitrogen is moved down through the soil profile and out of the root zone where it is not available to plants. The severity of nitrogen loss due to leaching is impacted the intensity and duration of rainfall. Denitrification is the process where soil nitrogen is biologically converted to gaseous nitrogen and lost to the atmosphere. During denitrification, microorganisms break down soil nitrogen and convert it to nitrogen gas when soil is saturated and oxygen is limited.
Nitrogen deficiency symptoms initially appear as a “V” shaped yellowing on lower leaves that begins at the tip and progresses toward the stalk. Nitrogen deficiency can also cause ears with tip-back, poor kernel set, and shallow kernel development. Fields that have experience excessive rainfall, ponding, and saturated soils could be exhibiting the symptoms discussed above.
While nitrogen deficiency has most likely impacted yields, another concern for eastern Corn Belt farmers this fall is stalk integrity. When nitrogen deficiencies exist, the corn plant will “cannibalize” its own stalk to produce an ear. As a result, stalks will be weakened and will be prone to lodging this fall. Fields where nitrogen deficiency has been observed should be harvested in a timely manner this fall to avoid harvest losses due to lodged corn plants.