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Revitalizing Iowa’s farm soils

By Staff | Dec 10, 2016

“And when you have less nutrients in crops, you have fewer nutrients available as animal feed or in human food.” —Bob Streit Crop consultant, Central Iowa Ag

FORT DODGE – According to Bob Streit, when farmers heard in 1965 that Iowa had enough micronutrients in the soils to last 45 years, what they heard was “forever,” not 45 years.

But in reality, according to Streit, an independent crop consultant with Central Iowa Ag, in Ames, that 45-year deadline clocked out in 2010.

“And when did SDS (sudden death syndrome), Goss’ wilt and other chronic diseases show up?” Streit asked. “In 2010.”

Streit was one of seven speakers during the two-day Farm News Ag Show in Fort Dodge held Nov. 30 through Dec. 1. He spoke Nov. 30, talking about how to revitalize Iowa’s soils.

“Very few of our corn fields are dark green,” Streit said. “They tend to be light-colored with streaking.”

He said Iowa’s soils are lacking in boron, manganese and molybdenum, all of which influence nitrogen use and plant uptake.

And because herbicides hinder the effectiveness of micronutrients, a soil lacking in them gets in even more trouble.

“And when you have less nutrients in crops,” Streit reminded his audience, “you have fewer nutrients available as animal feed or in human food.”

He also reminded farmers that the consumer is getting more aware of nutrition density in foods and will be demanding farmers do a better job in providing quality food.

The current 20-somethings, Streit said, will be farmers’ new bosses within 10 years as they become the primary food buyers of their families. And they are watching food trends.

As a result, he said the fertility industry needs to collaborate with human health mineral specialists to determine those key to human health and immune systems.

Test, test, test

Streit recommends that farmers conduct series of regular tests – soil, tissue samples, sap testing – to get a complete picture of their soil profile and what nutrients are available to plants during the growing season.

The relatively new sap testing, Streit said, “is like a blood test on humans and shows what is short.”

Because a field is showing light-green or yellowing foliage “doesn’t necessarily mean more nitrogen is needed,” he said. “It may need micronutrients.”

And the cost difference would be substantially less applying micronutrients than more nitrogen, he said.

Due to soils lacking in micronutrients, Streit said chronic crop diseases started showing up in heavier numbers in 2009 and 2010 including grey leaf spot, anthracnose, northern corn leaf blight, eyespot, diplodia, fusarium, comman and southern rust and Goss’ wilt.

He said his company has been running plot tests on corn with a product called Bio Empruv that is thought to defeat Goss’ wilt, and keeps plants greener longer, getting better grain fill, for two to three weeks longer than neighboring fields.

He said those fields were till green in mid-September, after neighboring fields were dead by Aug. 20.

According to Streit, the test plots, near Carroll and and Story City, were yielding 280 and 300 bushels per acre in some spots.


Corn root worms have proven they are an adaptive pest. Now, Streit said, some genetic lines are showing resistance to corn with all three Bt traits.

“Bt traits are failing,” Streit said. “Do not ignore the refuge requirements.”

He said results of research from University of Illinois showed that 40 percent of corn hybrids had barely enough toxin to kill root worm larvae, and 20 percent never had enough.

Depending on the corn variety, at V9 stage, the research found the best two genetics did not produce enough toxin to kill late-hatching larvae.

“Seed companies should have tested for toxin levels by variety,” Streit’s slide concluded.

He expects fields where insect pressure is not an issue could likely see conventional, or non-traited corn, planted in them, as a way to cut inputs costs.

However, he thinks eastern corn borers will be a problem in 2017.

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