From the Fields – Wheat Stands

FOR IMMEDIATE RELEASE
April 3, 2008

It will soon be time for wheat producers in northern Illinois to evaluate the condition of the winter wheat crop and make decisions regarding spring application of nitrogen.

As a general guide, when home lawns begin to show green color, winter wheat should be "breaking" dormancy and starting to grow. A stand of 25 to 30 plants per square foot is generally considered optimum. 15 to 20 plants per square foot is the minimum population needed to keep a field in the spring. The number of tillers can compensate, to a certain degree, for a low plant count. About 60 productive (head-bearing) tillers per square foot are needed for an adequate stand. Take stand counts at several locations across the field so a representative sampling is obtained.

When taking stand counts, check the condition of the crown of the plant. The crown, a source of carbohydrate storage, needs to be ¾ - to 1-inch below the soil surface. If the crown is firm and white and new roots are developing, the plant is probably in good condition. As long as the crown is alive, the plant can produce new leaves.

To get a head start on assessing the health condition of wheat, dig shovelful "plugs" of soil and wheat. Put them in a sunny, cool area (unheated enclosed porch) and check the crowns for new growth in about a week.

How much nitrogen is suggested? Until economic rate studies are finalized, University of Illinois recommendations depend upon soil organic matter and the presence of a legume underseeding. For example, in moderately dark-colored soils with 2 to 3 percent organic matter and without a legume underseeding, the suggested total nitrogen application range is 70 to 90 pounds per acre. With a legume underseeding, reduce the nitrogen rate by 20 pounds.

Be sure to give credit for any nitrogen that may have been applied last fall with phosphorus and potassium fertilizer. 10 pounds of nitrogen credit can be realized when wheat follows soybean and 30 pounds the first year following alfalfa.

The best time to apply nitrogen is in the early spring, when growth is resuming. Stands that are to be kept should be treated with nitrogen as soon as they begin to green, but before the joint stage. University of Illinois research has not shown a consistent advantage for splitting nitrogen application in the spring. Applying all of the nitrogen in the fall increases risk of loss, but it is a common recommendation to apply some nitrogen in the fall, at least 20 pounds per acre but no more than 40 pounds per acre. Uniformity of nitrogen application is important.

A 3-year study by The Ohio State University indicated that yields decrease substantially when nitrogen is applied after early stem elongation (Feekes growth stage 6, or when the first node or joint is visible). At this stage, wheat begins a period of rapid nitrogen uptake.

Further information is found in the Illinois Agronomy Handbook, available at University of Illinois Extension offices and at this web site http://iah.aces.uiuc.edu . In Ogle County call (815) 732-2191 for more information or go to www.extension.uiuc.edu/ogle .