Surface application of nitrogen fertilizer in late fall and early spring is a typical practice in South Dakota, however, the dry conditions this season may be putting that nitrogen in jeopardy, says SDSU Extension Soils Specialist, Ron Gelderman, during a recent iGrow Radio Network interview.
"With the weather being so very dry, warm and windy, and if we didn’t get that third to a half an inch of precipitation on that urea to move it into the soil and protect it, fields could have experienced some significant loss," Gelderman said.
Typically, moisture moves the nitrogen down into the soil profile where it is protected from loss, but the lack of moisture may have allowed some of the nitrogen to volatize. Gelderman says a soil test can determine whether the nitrogen is still there, however, he recommends waiting to soil test, and to have the lab analyze the sample for both nitrate and ammonium.
"We can’t assume that it’s all going to be lost. We think there could be significant amounts remaining. Problem is that some of it may still be in the urea form, and not too many labs can test for urea. So, what we’re suggesting is to soil sample later but still in time that we can fertilize these plants and still do some good," he said.
Gelderman says winter wheat, which is at, or close to jointing, will need a nitrogen application soon if significant loss of the applied urea occurred. Producers have more time before they need to test spring- planted grains and row crops. Gelderman says growers may want to use a urease inhibitor with future surface urea applications to increase the odds of getting some moisture.