It’s summer and your corn field is turning yellow – what’s going on? For many corn farmers, this is a sign of nitrogen loss. Nitrogen deficiencies are common following heavy rainfalls. In fact, the fields at the most risk for nitrogen loss following wet conditions are the ones where nitrogen was fall applied, followed by fields that had an early spring nitrogen application.
Symptoms typically first appear on the older leaves, then turn into a V-shaped yellowing that runs down the midrib of the leaf toward the stalk.
Severe symptoms you should watch for include:
- Pale yellowish-green color
- Stunted growth
- Spindly stalks
Management options for nitrogen deficiency include:
- Soil sampling: A late-spring test for soil nitrates can help you determine if nitrogen needs to be applied before the rapid growth begins. When corn plants are 6 to 12 inches tall, soil samples should be taken and analyzed, assessing the plant’s available nitrogen.
- General nitrogen application: A typical nitrogen application consists of 40 to 50 units of anhydrous ammonia, liquid or urea with a urease inhibitor, unless a test is used to determine the precise amount of nitrogen needed. If possible, apply nitrogen when there’s a chance of rain in the forecast, because occurrence shortly after application helps uptake in the root zone.
- Additional nitrogen applications: Consider adding another nitrogen application where plant loss has occurred. Yellowing fields with uneven growth that still have a chance to reach maturity and make grain are most worth investing in an additional application. To get the most benefit, agronomists recommend applying nitrogen to such areas as soon as possible, ideally before pollination. A late-spring test for soil nitrates can help you determine if nitrogen needs to be applied before the rapid growth begins. When corn plants are 6 to 12 inches tall, soil samples should be taken and analyzed, assessing the plant’s available nitrogen.
Contact your Golden Harvest Seed Advisor with questions or for additional agronomic insights.
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