July 9, 2010

Corn crop conditions vary widely across Nebraska, mostly due to higher than normal rainfall.

In many fields providing adequate nitrogen is a big challenge this year, especially where:

• rain has kept sidedress rigs out of the field,
• preplant nitrogen has leached or been lost, and
• nitrogen was scheduled to be applied with irrigation water.

Normally corn will take up about 60% of total nitrogen by V18. Uptake slows after that, but continues to move into the plant until R5 (dent) stage. Corn that is deficient will take up extra nitrogen between V18 and dent stage. Therefore, nitrogen can be applied after V18 stage. (V18, the 18th leaf, vegetative stage, occurs about one week before silking.) .

Plants that are severely stunted and yellow probably will not make maturity. Plants that are near normal height and growth stage, but exhibit slight nitrogen deficiency are probably the best candidates for supplemental nitrogen. Applying nitrogen to these plants is best done as early as possible.

Charles Shapiro, Extension Soil Scientist - Crop Nutrition
Haskell Agricultural Laboratory, Concord

Panhandle Nitrogen Update

The biggest corn is about 3 to 4 feet tall with later planted corn at the 10-leaf stage so hi-boy nitrogen application applicators can still get through fields.

Farmers who can only apply nitrogen through pivots should set their systems to 100% to apply 0.22 to 0.3 inches of irrigation. This small amount won't cause leaching problems, but with a big enough injector pump, it could apply up to 30 lb of nitrogen per acre in one shot. With two or three irrigations you could apply what you need without causing leaching.

Gary Hergert, Extension Nutrient Management and Soil Quality Specialist
Panhandle Research and Extension Center