Kansas wheat growers often welcome a blanket of snow over their fields, but that snow cover may impede nitrogen effectiveness, according to Kansas State University scientists.
"We have observed in Kansas that when nitrogen is applied on top of snow cover, wheat yields are sometimes not as good as when nitrogen is applied to fields without snow cover," says K-State Research and Extension soil specialist Dave Mengel. "This applies to both dry urea and liquid UAN applications."
Why this happens is not entirely certain, because there would be no cause for volatilization, adds K-State agronomist Scott Staggenborg.
One possible reason is run-off, as N applied in this manner may sometimes move along the surface of the field as the snow melts, Staggenborg says. Nitrogen could be carried off the field or redistributed within the field, resulting in some areas of the field ending up with too much fertilizer N and some areas having an N deficiency. The end result would be an overall reduction in yield, compared to fields in which there was no snow cover when the N was applied.
The agronomists said further information on this topic is available in a recent article from South Dakota State University on the Plant Management Network Web site: