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Farmers share nutrient reduction strategies

By Jean Caspers-Simmet

Date Modified: 02/24/2014 11:25 PM

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AMES — Tim Smith and Seth Watkins farm in different parts of Iowa and have different types of operations, but both are employing practices to manage soil nutrients.

Smith and Watkins shared their experiences with cover crops, strip-till, bioreactors and prairie strips during the recent Practical Farmers of Iowa annual conference in Ames. Their presentations on how farmers are implementing the Nutrient Reduction Strategy was in partnership with the Iowa Learning Farms.

Smith, who farms near Eagle Grove, told PFI members he has adopted practices that reduce nitrogen and phosphorus runoff by at least 40 percent, the goal of Iowa's Nutrient Reduction Strategy.

"If I can do it, so can you," Smith said. "I'm nobody special. We all need to do it."

Smith and his wife, Lana, farm 850 acres using CRP, cover crops, strip-till, a nutrient management plan and a bioreactor to protect soil and hold nutrients.

Smith's land is on Eagle Creek in the Boone River Watershed, which is part of the Mississippi River Basin Healthy Watersheds Initiative.

When Smith signed up for MRBI, he was interested in strip-till, but soon signed on for cover crops, changed the way he applied nitrogen and agreed to install a bioreactor.

"It's like going to the store for a loaf of bread, and when I came out, I had a whole cart of groceries," Smith said.

In early September 2011, his first year with cover crops, an airplane seeded one bushel of rye per acre into standing corn and soybeans.

Smith calls cereal rye, the beginners' cover crop.

"My goal for 2014 is to introduce another species, maybe radishes or something like that," Smith said.

Cover crops double the time living green plants cover the soil. At 8 to 10 inches tall, rye generates 800 pounds of biomass per acre, Smith said. It takes up 30 pounds of nitrogen, a savings of about $15 per acre.

"That probably would have gone down the tile line," Smith said. "Cover crops sequester nitrogen and keep it out of the water."

He used to apply nitrogen in the fall after the temperature dropped and used a nitrogen inhibitor. Now he delays application until spring or at side-dress time. He uses the late spring nitrate test, takes tissue samples prior to silking and uses a late-season stalk test to see if he applied the correct amount of fertilizer. He grid soil samples on 2.5-acre grids and follows a written nutrient management plan.

Smith installed a wood chip bioreactor in 2012, which denitrifies tile water before sending it back into the stream. It reduces nitrates in tile water by 30 percent to 50 percent. The bioreactor treats 30 to 40 acres.

Working with an Iowa Soybean Association water monitoring program has shown him that what he does in north central Iowa affects others, Smith said.

Watkins farms near Clarinda in southwest Iowa.

"It's cattle country," he said. "We have rolling highly erodible land with a low corn suitability rating, but we also have some aces that are very good land."

Watkins' Pinhook Farm consists of 3,000 acres in Page, Taylor and Adams counties. He has 2,400 acres of pasture, 400 acres of corn, wheat and hay, 200 acres of CRP land and land set aside for wildlife. He runs 600 cows and also provides outfitter services.

"Stewardship is our number one priority," Watkins said.

He achieves his stewardship goals by maintaining an open mind and minimal debt. He uses no-till, tile and terraces coupled with cover crops, photo points to monitor grazing areas, riparian buffers, shallow water habitat, late season calving, rotational grazing, and prairie and pollinator habitat restoration.

Watkins is also growing strips of native prairie, a new conservation practice pioneered at the Neal Smith National Wildlife Refuge, which reduces soil loss, slows runoff and creates vital patches of native habitat on row-cropped farms. Watkins, in consultation with Iowa State University's Science-based Trials of Rowcrops Integrated with Prairie Strips research team, seeded a 50-acre field with about eight acres of prairie.

From 2008-11 researchers found that the Neal Smith prairie strips resulted in 95 percent reduction in sediment and 90 percent reduction in total nitrogen and phosphorus export, Watkins said. Plant and bird diversity increased where strips have been established.

"That means we're keeping valuable nutrients in Iowa where we can make a better living, and the shrimp boat captains in the Gulf have a better chance to make a living as well," Watkins said. "That's the definition of a win-win. Strips address what really matters: Being able to say I left the land better than I found it."