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Strategies and studies

By Staff | Dec 14, 2018



There are many ways to reduce nitrates getting into Iowa’s rivers and streams, as outlined in Iowa’s Nutrient Reduction Strategy.

Which ones work the best? Where might one work that doesn’t work in another location? What’s the best way to make nutrient reduction economically feasible?

These questions, along with new data from Iowa State University studies, were presented last Wednesday morning at the Farm News Ag Show by featured speaker Matt Helmers, director of the Iowa Nutrient Research Center.

But the big question was one Helmers wanted answered by his audience, many of whom were farmers.

“I know I’m speaking to the choir. So I’ll ask you-how do we get people to try that?” Helmers said.

The Iowa Nutrient Reduction Strategy began in 2013, in response to a task force looking at the large hypoxia zone in the Gulf of Mexico caused by nutrient runoff into the Mississippi River. Hypoxia is a large area of low oxygen that can’t sustain marine life. Nutrients that lead to algae growth are the main culprit.

Recommendations in the strategy have been voluntary.

In the audience of about 25 people, many had tried innovations like no-till, cover crops, and buffer strips to decrease the nutrients reaching the river system. But getting more people involved is the challenge, Helmers said.

“I don’t think we’re going to make progress on this until we get bankers and co-op agronomists behind this. Those are two of the biggest influencers,” one farmer said from the audience.

Another added, “I frankly think the only way you’ll see widespread adoption of some of this is for the state to step in and mandate – just get people out there doing something on a trial basis,” saying he’s had good luck with cover crops himself.

“When we think about the challenges, and the scale of change that’s needed, especially in tough financial times, it is a huge challenge. Some would say, let’s just mandate across the board,” Helmers said.

Helmers spoke about nitrate reduction mandates in New Zealand and the European Union. He spoke with farmers from multiple countries on a trip earlier this year. In Denmark, for instance, farmers were required to cut back the amount of nitrogen they apply – and were then compensated for the resulting loss of production. In New Zealand, farms have benchmarks they must hit in terms of nitrate flowing out, and can develop their own plan to meet that.

“If we did something like either of those would that drive change? Yes. Would it limit the flexibility to implement different practices in different places? That’s my concern,” he added.

In some cases, more judicious application of nitrogen can help.

Helmers said one study of five drainage districts found applications rates everywhere from 120 pounds per acre to more than 200 pounds per acre for corn following beans.

“Those folks that are at over 200 at corn following beans, you think there might be a potential to reduce that slightly? Do you think that would help their bottom line? Do you think that would help the environment? Yes,” he said.

On the other hand, management certainly won’t solve the problem. Even on ground where no nitrogen at all has been applied, nitrate still forms and can run off due to natural processes in the soil. Helmers said land with no nitrogen shows about a 45 to 50 percent reduction in nitrate in one study.

Since the strategy aims for a 45 percent reduction in nitrates overall, and farmers can’t just stop using nitrogen, clearly management alone isn’t the solution.

Cover crops can also help, but that won’t work everywhere for everyone.

“People say we just need a third crop. I wish it was that easy,” Helmers said. “Is there anything that is as profitable as corn and soybeans? No. What if we planted 4 million acres of oats?”

“Where’s the market?” a farmer asked.

“Exactly,” Helmers said.

One study near Gilmore City showed a 5 percent reduction in nitrate loss, both in the corn phase and the soybean phase, even when the cover crop didn’t grow well.

“To me that’s been encouraging,” Helmers said.

Cover crops can especially help absorb extra nitrate during a drought year, he said. However, that only works if the cover crop can grow in spite of the drought.

Researchers are also looking into whether drainage water could be collected in a pond, then re-sprayed on fields as irrigation. Two places in Calhoun County are currently designing such a system, he said.

“I think this is important to study. It could be a game changer if it works,” he said.

In another new study from northwest Iowa, applying nitrogen at two times later in the season decreased runoff without hurting yield, Helmers said.

One plot had anhydrous ammonia applied in fall, he said. One got anhydrous in the spring, and one was split, with 30 pounds of nitrogen as a starter, and 90 pounds applied “sidedress” – between rows of growing crops. The fourth plot had no nitrogen applied.

In two of the three years, corn yield was the same in all fertilized fields. It was, of course, lower in the unfertilized one.

But nitrate runoff from the split field was as low as runoff from the field with no nitrogen, he said.

Another study in the northeast showed an improvement in yield from applying manure later in the fall, instead of earlier. Applying manure in the spring showed even more improvement under certain conditions.

Timing of manure application was a challenge for one farmer in the audience.

“I see a potential problem coming next spring. I’m further north here, and a ton of hog buildings have gone up,” he said. “We’ve signed on to take some manure. They put that manure on yesterday.

“It’s a concern. (First), you’re generally putting it on at a higher rate than-they’re more looking at the legal limits when they apply than what an appropriate rate would necessarily be. And I look at putting this on frozen ground-it scares me.”

Helmers agreed this is a concern, and said another challenge is finding ways to store manure until the best time to apply it.

“I can tell you the story they gave me on that, was, you’re not going to be able to plant your crop until we get this applied, and you might be waiting until June,” the farmer said.

Another farmer, Bob Ritter, said he’d had success in turning part of his land over to the Iowa Heritage Foundation, which will someday change it into a wetland.

“There are tax credits, on your state tax. It has worked out very well at the end of our farming career to get those credits,” Ritter said. “They have it all planned out to dredge it out.

“This isn’t an overnight thing. But if people look ahead a little bit and think about your drinking water, and what these wetlands can do”

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