You might be able to save money by buying and applying urea fertilizer now rather than in the spring. But, in South Dakota, the wild card is snow cover, says Ron Gelderman, SDSU's Soil Testing Lab manager.
"We've looked at an SDSU study from 2006-2007 that was done at seven winter wheat locations and seven spring wheat locations, covering the wheat (growing) areas of western and central South Dakota," says Gelderman. "It showed that when there was significant snow cover and N was surface broadcast, yields averaged about 18% lower than where N was placed in the soil."
On locations with little snow, winter applications were similar to in-soil applications
Applications to frozen fields without snow cover is not recommended on sloping fields because of runoff potential, Gelderman adds.
While fall, early spring, and late applications -- some as late as the five-leaf stage -- all had similar yields, soil application led to the highest yields over all sites.
"The reason behind the lower yields is not clear since a non-volatile N fertilizer was also used and had similar yields to the urea treatment," Gelderman says. "So it doesn't appear gaseous N loss was the issue. In addition, runoff was limited on these relatively level sites."
The South Dakota Wheat Commission funded the study.
Source: SDSU AgBio Communications