Des Moines Register
06-12-07
Wet weather makes farmers play a 'guessing game'
Corn can recover from a poor start, if lost nitrogen is replaced - but will the investment pay off?
By JERRY PERKINS
REGISTER FARM EDITOR
Kenny Lund spent much of last weekend testing the soil on his farm fields for nitrogen, hoping against hope that the rain that has saturated his farm near
Sheldahl this spring hasn't robbed the soil of its precious supply of the corn fertilizer.
"The corn looked pretty tough," Lund said. "That's why I got concerned and tested the soil."
Soil samples showed some of Lund's cornfields were low in nitrogen, he said, and others showed there was enough nitrogen to grow a good crop. That's the case in many areas of central and southwest Iowa this spring, crop watchers say.
The level of nitrogen in the soil is crucial, experts say, because:
- Lack of adequate nitrogen hurts corn yields. Good corn yields are needed this year, agricultural market analysts have said, because of the boom in ethanol production.
- Applying extra nitrogen to make up for fertilizer leached from the soil costs farmers money in a year in which many crop inputs are more expensive.
- And nitrogen fertilizer washed out of farm fields inevitably ends up hurting the quality of Iowa's waterways.
The U.S. Department of Agriculture forecast Monday that domestic demand for corn in the 2007-08 marketing year is expected to be 12 percent more than in the current year. U.S. farmers told the USDA they intended to plant the most corn this year since 1944.
Roger Elmore, an Iowa State University agronomist , said Monday that the condition of the state's corn crop varies widely from area to area and even within fields.
"There is a huge variation in corn growth," he said. "This is not setting up to be as good a year as we've had in previous years."

Corn can recover from a poor start, Elmore said, and forecasts for warm and dry weather bode well. "If the corn doesn't respond to this week's weather, it might need some more nitrogen" to promote growth, he said.
Tracy Blackmer, director of research for the Iowa Soybean Association, said
Monday that the southwest quarter of Iowa has been especially hard hit by rain, leaving that area vulnerable to nitrogen leaching.
"Our research shows that the more rain you have in the spring, the more at risk you are for losing nitrogen," Blackmer said.
State climatologist Harry Hillaker said May rainfall in Iowa averaged 5.27 inches, more than an inch more than normal.
West-central Iowa reported 7.04 inches of rain in May, Hillaker said, and southwest Iowa had 9.8 inches, where it was the wettest May since 1996.
Rainfall in Iowa last week averaged 0.23 inch, Hillaker said, compared with the normal 1.23 inches.
Blackmer said excessive rainfall like that seen in southwest and west-central
Iowa leads to a lack of nitrogen in the soil and more crop stress.
Losing nitrogen from farm fields also means that more nitrogen enters the state's waterways through runoff and through tile lines, he said. Studies have linked nitrates in water to cancers, miscarriages and other health problems.
Tracy Blackmer's father, Alfred Blackmer, was a professor of agronomy at Iowa
State who pioneered research into testing soils for nitrogen fertilizers in the spring so farmers can gauge whether they need to apply more.
Alfred Blackmer, who died in 2006, often warned Iowa farmers that if they didn't manage their use of fertilizer wisely, they could count on more government regulation of their farming practices.
Alfred Blackmer's work led to the establishment of the Iowa Soybean
Association's On-Farm Network, which enlists farmers in nitrogen management research and is directed by his son.
Shelia Hebenstreit, an agronomist at West Central Cooperative in Jefferson, said farmers have been requesting soil tests for nitrogen since several large rains hit the Greene County area in May.
"We know we've had some losses (of nitrogen), but we don't want to put nitrogen on where we don't need it," she said. "Applying more nitrogen is a huge

economic decision for a farmer to make. You can't afford to put it on unless you really need it."
Jay Ostrander, who farms near Jefferson, said soil tests are showing him that some fields are low in nitrogen and some have adequate levels.
"I'll take some more tests in the next couple of weeks and see how we're doing," he said. "It's a guessing game. It's tough to know if you are going to get your money back" from applying more nitrogen.
Farm Editor Jerry Perkins can be reached at (515) 284-8456 or jperkins@dmreg.com