In this week’s Crop & Pest Report (https://www.ag.ndsu.edu/cpr), Dr. Franzen of NDSU wrote that high (but still within recommended rates) levels of pre-plant N fertilizer application on small grains does not cause yield reduction when crops experience drought later in the season. This is because adequate soil N enhances tillering and root growth, which consequently improves the crop’s ability to use water from a larger volume of soil.

Do we still need to side-dress corn or wheat even though we anticipate crop drought stress this summer?

Despite current shortage of rainfall in North Dakota, sub-soil moisture has been quite helpful in sustaining crop growth. If N side-dress is part of your spring fertility program, timing should depend on your goal to increase yield or grain protein.

• To enhance grain yield, consider stream-bar application of UAN between 4-leaf and jointing.
• To enhance protein, apply UAN immediately post-anthesis. 

But what happens if I add N to my corn during a prevailing shortage of rainfall?  Corn does not tiller, and has broader leaves than wheat.

Corn is more susceptible to drought stress due to evapotranspiration from its broad leaves. The current situation, however, does not yet prevent a farmer who had plans to side-dress N but is anticipating prolonged drought and crop stress.

Things to remember before side- or top-dressing corn

• In high-productivity, high-clay soils, side-dress N is encouraged. This is especially important for clay soils with high susceptibility of N denitrification when the soil is wet. N can be side-dressed with UAN using a coulter.
• On medium texture (loam, sandy-loam, loamy-sand, or silt loam) to sandy soils, anhydrous ammonia should be applied, 5-6 inches deep.
• Application can be made to every other row.
• If urea is to be used, consider urea that is coated with a proven commercial product like Agrotain® (or others with NBPT coating) to keep the N stable and minimize ammonia N loss for about 10 days. Apply as top-dress at < 100 lbs urea/ac (or 46 lbs N/ac).
• Recommended growth stage to side-dress corn in North Dakota is V5 to V6.

Acknowledgement of Dr. D. W. Franzen for permission to reference his article.

Jasper Teboh
Jasper.Teboh@ndsu.edu
Soil Scientist