Des Moines Register
07-19-06
Heat punishes livestock, crops
By ANNE FITZGERALD
REGISTER AGRIBUSINESS WRITER
This weather isn't fit for humans, plants or animals.
Hogs eat less, dairy cows give less milk and feeder cattle gain less weight when
it's so hot.
"My fat cattle in the lot don't do well at all. They just don't gain much when it's
hot," said Jamie Fopma, who feeds cattle north of Sully and helps oversee seed
corn production in central Iowa for Monsanto Co.
Bruce Bentley, a Macedonia row crop farmer and cattle feeder, said heavy cattle
are most at risk. "The big trouble is when it doesn't cool down at night," he said.
"This is a critical time to have cooler temperatures and moisture available," said
Roger Elmore, ISU Extension corn specialist in Ames. "Above 90 degrees is
not conducive to a lot of plant growth."
Crop and livestock production in Iowa is a multibillion-dollar business. What
happens across the countryside during July has a long economic tail, affecting
not only farm income, but also Main Street businesses and suburban shopping
malls, economists say. Also affected are grain processors, ethanol
manufacturers and livestock feeders.
"The high heat indexes are always a problem for cattle, hogs, poultry," said John
Lawrence, an ISU Extension economist and director of the Iowa Beef
Center in Ames. In parts of southern and western Iowa, where dryness has
been most severe this summer, pastures have turned brown, while farm ponds
and other water sources have dwindled.
Excessive heat and high humidity can be fatal to farm animals. In mid-July 1995,
the combination killed an estimated 3,800 cattle in a 14-hour period in westcentral Iowa, said Darrell Busby, ISU Extension's beef specialist in
southwestern Iowa.
He and other livestock specialists have helped producers devise ways to prevent
that from happening again. Some cattle feedlot operators use sprinklers to
dampen ground, which can help animals at the height of summer heat.
It is too soon to tell precisely how this summer's high temperatures will affect
Iowa's two top crops, agronomists and other crop specialists said Tuesday.
On the upside, today's corn hybrids and soybean varieties are more stress
tolerant.
Also a positive: Weather conditions in the spring favored good root development.
Iowa headed into the growing season with recharged soil moisture, and most
corn and soybean roots reached seven feet deep, enabling plants to draw on
deeper soil moisture, said Elwynn Taylor, ISU Extension climatologist. But
with soil moisture levels dropping, "we are about done with getting by on the
storage," Taylor said.
At this stage, cornfields across the state need at least three inches of rainfall in
July and August to produce above-average yields, he said. Soybeans need two
inches of rainfall this month and another three inches in August, when that crop
sets pods.
"They need a drink of water kind of bad," said Loren Schnepf, who raises crops
and feeds cattle near Le Mars. "We're not going to have the crop we have had
the last couple years."
Reporter Anne Fitzgerald can be reached at (515) 284-8122 or
afitzgerald@dmreg.com
Water needs
The higher the heat, the more crops consume. For every 10-degree increase in
daytime temperature highs, plants need twice as much moisture, said Elwynn
Taylor, Iowa State University Extension climatologist. Here's how it works:
- With highs of 74 degrees, plants consume about an inch of water weekly.
- With highs of 84 degrees, plants consume two inches per week.
- Highs of 94 degrees - expected to be exceeded today in portions of the U.S.
Corn Belt - increase the weekly need to four inches of moisture.
Temperatures higher than that can hurt yields.
"If that goes on day after day, that's a setback, even if the plants have water,"
Taylor said. "If this heat spell goes on much longer, the plants will die. Some are
already dying."