Jeff Burbrink

Around Area Farms



One of the first signs of spring is the greening-up of the wheat! That is also a sign it is almost time to fertilize the wheat.

University recommendations from Purdue, Ohio State and Michigan State all agree that the best time to apply nitrogen is between green-up and early stem elongation. The potential for nitrogen loss will decrease by waiting to apply closer to stem elongation; however, since we are seeing some green-up already, a common-sense approach would be to apply as soon as field conditions are dry enough to allow application equipment, particularly since days available for field activities may be limited between now and stem elongation.

The Tri-State Fertilizer guidelines base nitrogen rates on yield potential of a field. As a producer, you can greatly increase or reduce your N rate by changing the value for yield potential. To select a realistic yield potential, look at wheat yield from the past five years. Throw out the highest and lowest wheat yield, and average the remaining three wheat yields. This three-year average should reflect a realistic yield potential.

Once you have selected a value for yield potential, the recommendation may be based on the following equation for mineral soils, which have both 1 to 5 percent organic matter and adequate drainage:

N rate = 40 + [1.75 x (yield potential – 50)]

No credit is given for the previous soybean or cover crop, since we do not know if that organic N source will be released soon enough for the wheat crop.

The Tri-State recommends that you subtract from the total nitrogen any fall applied N up to 20 lb/A. Whether you deduct fall N depends how much risk you are willing to take and your anticipated return of investment from additional N.

As an example, based on the equation above and deducting 20 pounds for a fall application, the university recommendation a spring application of 90 pounds N per acre for a yield potential of 90 bu, 70 for 80 bu. potential and 40 for a 60 bu. potential.

Jeff Burbrink is an Extension educator in agriculture and natural resources. Write to him at 17746 E. C.R. 34, Goshen, IN 46528; call 533-0554; or fax 533-0254.