CROP UPDATE: Higher organic matter soils, wheat price determine fertilizer use

Posted: Mar. 20, 2013 12:32 pm Updated: Apr. 19, 2013 1:15 pm


A few years ago the University of Illinois adopted new guidelines for nitrogen application on wheat. Based upon recent research the new guidelines look at soil organic matter as one of the determining factors when deciding on how much nitrogen to apply.

The reason is that higher organic matter soils are providing more nitrogen to the crop, so no need to spend extra dollars on those soils. The other factor is wheat price. When wheat prices are higher, we can afford to fertilize at higher rates because the return can be greater.

For most folks in our area, these new recommendations call for higher rates than what we've normally applied. Looking at summer wheat price and the price of urea today, 150 pounds of nitrogen per acre for this spring would not be out of line. This rate assumes you already applied 25-30 pounds of nitrogen in the fall (about 150 pounds of DAP).

The rates are based upon how many pounds of nitrogen one bushel of wheat could buy. For instance, using prices of $500 per ton for urea and a $7 wheat price would equate to one bushel of wheat buying about 13 pounds of wheat. In a low organic matter soil (soil less than 2 percent) would indicate that 150 pounds of nitrogen would be recommended. A higher organic matter soil (2-4 percent) would suggest a rate of 100 pounds per acre.

Keep in mind that at these higher rates, the accuracy of spread needs to be good. Overlapping of nitrogen (doubling the rate) would no doubt cause lodging problems. Timing of application during spring green up (Feekes growth stage 3 or 4) is recommended.

If clover is to be added with the nitrogen, you'll not likely be satisfied with the results. Such high rates of nitrogen would stimulate the wheat to the point that it would out-compete any new seedling.