Mid-Season Nitrogen Tips, Application Guidelined

 If the intent of a mid-season application is to increase protein, consider that the largest increase you are likely to see in protein as a result of a mid-season addition of nitrogen is probably no more than one whole percent increase, i.e., for example, an increase from 13 to 14%. The only exception that is likely to occur is in sites that were very nitrogen-deficient at the time of planting.

 By the time the wheat crop starts heading out, it has accumulated nearly all of the nitrogen that will eventually show up in either grain yield or protein. Consequently, nitrogen applications should be made as soon after tillering as possible and before flowering and pollination, if at all possible.

 Any split applications should be avoided during the actual pollination period, mainly because of potential injury to the flowering heads and the addition of undue stress to the crop.

 Following heading, nitrogen applications that are going to be made would be best made as foliar applications at relatively low rates, 10 - 20 pounds per acre at the most. Otherwise, there is a good possibility of causing damage to the plants.

 Time applications to coincide with cool periods and when there is either moisture from previous rainfall or dew on the plants.

 Split applications of nitrogen will not do much good with regard to protein or yield increases unless the crop has adequate amounts of available water, either from stored soil moisture or from supplemental irrigation supplies.

 Between 65 and 75% of the nitrogen in the plant parts is translocated (moved) to the grain during seed formation and filling.

 Grain protein percentage is closely related to top growth. Nitrogen percentage of the stems and leaves declines rapidly with advancing maturity.

Under what conditions will a producer likely see a protein increase by applying nitrogen to spring wheat? I would say, given the following conditions:

1) Uniform, full stand with good to excellent heading.

2) Little or no residual nitrogen in the soil at present, either because the spring rate was cut back or production has out-performed previous yield projections.

3) Heads have not begun to fill (through flowering and early after pollination).

4) There is still plenty of available moisture in the soil.

5) The variety is relatively high yielding and the yield potential appears to have exceeded the available nitrogen.

6) Weather conditions are relatively cool, moist, and the crop still has a chance to take up some additional moisture and nitrogen.

7) The nitrogen application is made as a relatively low-rate foliar application or followed immediately by a light irrigation or rainfall event.

—Jim Bauder, Montana State University extension soils and water specialist

Foliar Fertilization of Wheat for Protein Content  Enhancement
Spring wheat growers receive returns based on bushels and protein content. Research at the 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, 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%. In a South Dakota study from 1995-2000, 30 lbs of UAN mixed 1:1 with water increased spring wheat percent protein an average of 1/2% when applied post pollination. Pre-flowering application averaged an 0.3% protein increase. Post pollination application increased protein 70% of the time when the yield goal was exceeded as compared with only 23% when it was not exceeded. 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 Service