Topdressing N on Small Grains

Growers who want to gamble and take advantage of higher yield potential may want to try topdressing their small grains. Topdressing after the 3-leaf stage will help head size, spikelet number, and kernel number, all of which are yield component decisions that the wheat plants make.

Hot and/or dry weather later on, particularly at 4-5 leaf stage and at pollination, will modify any improvements that the N additions would make. Also, whatever topdressing strategy is employed, it must rain following application before the 6-leaf stage for the fertilization to be effective.

My favorite application would be liquid N (UAN, 28-0-0) applied with streamer bars about the 4-leaf stage. Do not broadcast the UAN; the burn will be great and may cause a yield reduction in some cases.

Streamer bars concentrate the application into bands, which tend to drive most of the fertilizer to the soil surface rather than coat the leaves, where it could damage the leaf tissue and cause “burn.” A concentrated band also slows the rate of urea volatilization from the urea portion (the N in UAN is about 50% urea) of the UAN.

The ammonium nitrate half of the UAN solution is not subject to volatilization, making UAN a preferred fertilizer over dry urea for this type of application. Application with streamer bars most effectively avoids burning on calm days. The danger of burn increases as the wind increases. Under windy conditions, the wind breaks the stream apart and converts it into a poor broadcast application, coating leaves and increasing burn.

If dry urea is used, it might be wise to also have it coated with Agritain®, which is a tried, tested and proven urease inhibitor, and gives about 10 days of protection from volatility.

Whichever source is used, rain is required to move the N into the soil so that roots can utilize it. About 1/4 inch of rain is needed in bare soil to accomplish this, and with residue, the more rainfall is needed, particularly if there is a thatch cover. If rain does not fall until after the 6-leaf stage, yield will not be enhanced.

Side-dress Timing, Corn & Sunflower
Side-dress for corn should start when the corn is tall enough that clods do not cover the young plants. Yield decisions do not begin in earnest in corn until about the 9-leaf stage. Usually 5-8 leaf corn is ideal. Corn can physically be side-dressed until the equipment starts snapping off stalks. But it’s better to apply it earlier than that.

Sunflowers can be side-dressed when clod movement danger is past, to when they are too tall to physically get through. Usually 6-18 inches is best.

—Dave Franzen, NDSU extension soil specialist

Sclerotinia Risk Map for Canola Online

Sclerotinia risk forecasting maps for North Dakota and northwest Minnesota can be found online: www.ag. ndsu.nodak.edu/aginfo/sclerotinia/sclerotinia.htm .

Enhancing Wheat Protein with Foliar N Fertilization

Research at the NDSU Carrington Research and Education Center, and the University of Minnesota Crookston Station show that grain protein content can be enhanced by foliar application of nitrogen fertilizer post-anthesis. Soil N levels at Carrington were just adequate for yields achieved in the study, while the plots at Crookston contained soil N levels in excess of needs. At Carrington, 30 lbs N/acre as a 1/2 water/28% solution increased grain protein about 1%. At Crookston, 30 lbs N/a increased grain protein about 1/2%. The decision to foliar treat with nitrogen should be based on costs of the treatment, protein premiums offered, and considerations of soil N levels, fertilizer applied and anticipated yield goals. Apply liquid fertilizer in a diluted form if possible on wet foliage and in cool temperatures to reduce burning.

– Terry Gregoire, NDSU Extension Servicec