Des Moines, Iowa
August 21, 2008
Research from
Pioneer Hi-Bred, a DuPont
business, and Kansas State
University shows corn growers should continue to irrigate
into the grain-filling stage. Researchers say stopping
irrigation too soon can cause significant yield loss.
A four-year field study was conducted in northwestern Kansas to
evaluate effects of delaying the first irrigation or premature
termination of the irrigation season on corn grain yield and its
physiological components. Results from the Pioneer-commissioned
study at K-State Northwest Research and Extension Center in
Colby, Kan., confirmed the corn vegetative stage prior to
tasseling is the least sensitive to water stress while the
grain-filling stage is highly sensitive to water stress.
"The grain-filling stage is the second most critical stage in
corn with pollination being the most critical." says Freddie
Lamm, research irrigation engineer for K-State Research and
Extension. "Yield can be negatively impacted during grain fill
by weather conditions such as excessive heat, solar radiation,
wind and lack of rain. Late-season irrigation is one tool that
can be used wisely to minimize any negative weather effects so
grain filling can continue and not be ended prematurely."
Corn kernels are formed and experience rapid growth during the
last 60 days of the growing season right up to maturity, and
readily available water is a necessity. "Daily yield gains of 4
to 5 bushels per acre are possible under good growing conditions
during grain fill and daily yield increases of 2 to 4 bushels
per acre are common" says Lamm.
"Growers need to look at several factors before beginning an
irrigation event," says Tom Doerge, Pioneer agronomy research
scientist. "This includes reviewing the types of soil for each
field, looking at how well that soil stores water reserves and
also the stage of the corn. Growers can contact their local
Pioneer agronomist for assistance on assessing water reserves
and soil type." After reviewing these factors, local past
experiences with late summer weather and crop maturity should be
considered.
Irrigation is a costly procedure with today´s energy prices and
sometimes uses scarce water resources, so it is understandable
that producers would want to stop irrigating as soon as
practical, says Lamm. Results from this study, however, show
that when needed, an inch of late irrigation often can increase
corn yields by 20 bushels per acre.
"Irrigation planning should be based on sound information about
the crop, soil water reserves and weather conditions," says
Lamm. "A specific calendar date for ending the irrigation season
may be the worst choice. Producers need to be flexible and make
decisions about the last irrigation event based on anticipated
crop water needs and rainfall."
Long-term field studies and climate-based calculations of corn
water use during the last three weeks before maturity indicate
that an average of 3 to 4 inches occurs in western Kansas. This
water use can be obtained from a combination of soil water
reserves, rainfall and irrigation.
"One problem that occurs is that producers sometimes rely too
much on soil water reserves that may have become overly depleted
during the season" says Lamm. "Past studies have suggested soil
water reserves could be depleted as much as 80 percent during
the final stages of corn production without harming yield.
"That has not been our experience in this study. Yield
reductions began to occur when available soil water reserves
were as high as 50 percent. It seems likely that with the great
corn hybrids and other advanced production technologies we have
today, that less water stress can be tolerated without an
appreciable economic impact. For example a 5 percent reduction
on 125-bushel-per-acre corn is much less important than a 5
percent reduction on 225-bushel-per-acre corn."
The study was conducted on deep silt loam soil using two
Pioneer® brand hybrids and a subsurface drip irrigation system.
"This type of research offers growers sound agronomic advice on
how to better manage their irrigation schedules," says Pioneer's
Doerge. "The research is particularly valuable to those who are
impacted by declining water sources."
The study was part of the Pioneer Crop Management Research
Awards (CMRA) program that provides funds for agronomic and
precision farming studies by university and USDA cooperators
throughout North America.
Pioneer Hi-Bred, a DuPont business, is the world's leading
source of customized solutions for farmers, livestock producers
and grain and oilseed processors. With headquarters in Des
Moines, Iowa, Pioneer provides access to advanced plant genetics
in nearly 70 countries.
DuPont is a science-based products and services company. Founded
in 1802, DuPont puts science to work by creating sustainable
solutions essential to a better, safer, healthier life for
people everywhere. Operating in more than 70 countries, DuPont
offers a wide range of innovative products and services for
markets including agriculture and food; building and
construction; communications; and transportation.
TM, ® Registered trademarks of Pioneer Hi-Bred.
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