Farm News, IA
06-13-07
N losses mount in corn
By Kristin Danley-Greiner, Farm News staff
Rockwell City-area farmer Tom Hiler, left, attended a Monday crop scouting
workshop near Rockwell City hosted by Mark Licht, an Iowa State University
Extension crops specialist, who is showing Hiler disease problems that may
crop up this season.
The heavy rains that fell earlier in Iowa apparently are still having a lasting
impact.
Dan Thompson, an agronomist with Pioneer, said farmers in some areas are
reporting yellowed and stunted corn plants, but the causes have been
widespread, among them rain robbing nitrogen from plants. Thompson said
where nitrogen deficiency is suspected, producers are encouraged to take a
spring soil nitrate test to be analyzed.
“Causes could range from nitrogen deficiency, cool damp growing conditions
causing stress, slow root development or the genetic makeup of the plant—some
varieties are just a lighter color green than others,î” Thompson said. “In most
cases, we are seeing the lighter corn mostly in corn on corn fields.î”
Roger Elmore, Iowa State University (ISU) agronomist, said if soils dry out
and the corn plants do not recover, there likely is a nitrogen issue.
“If indeed the corn does not recover, a sidedress application of nitrogen may be
in order,î” he said.
Don Elsbernd in Allamakee County said his area has received more rain than
normal, but flooding hasn’t been a problem. Still, some plants are yellowing.
“Low spots and side hill seeps are beginning to show yellow because of the
rains, and nitrogen loss in these isolated areas will occur,”î he said. “Farmers can
sidedress extra nitrogen if needed, but in most cases, the areas will be too small
to mess with.Ӕ
Soybeans very rarely are nitrogen deficient, since they fixate their own nitrogen
from the nodules on their roots. Palle Pedersen, ISU agronomist, said 50
percent of a soybean’s plant comes from fixation and the remainder comes from
the soil. Mick Lane, research communications manager for the Iowa Soybean
Association (ISA), agreed that nitrogen deficiency in soybeans is rare. So in the
case of soybeans, Thompson suggested producers spent time scouting for insect
pressure, since first generation bean leaf beetles are active.