Nutrients

Nutrient management a gradual evolution

2014-03-06T07:00:00Z Nutrient management a gradual evolutionBy Zoe Martin, Iowa Farmer Today Iowa Farmer Today
March 06, 2014 7:00 am  • 

ROWLEY — Buchanan County farmer Dick Sloan remembers his father heading to the fields with a four-row planter and garden rototiller.

When Sloan joined him in the late 1970s, minimum tillage and nutrient-management practices were new ideas.

Iowa’s water-quality and nutrient-management history goes back to the 1930s, when the first known state comprehensive water-planning effort was conducted.

The 1972 Clean Water Act targeted pollution from point sources, such as wastewater treatment plants, but focus on farm runoff didn’t come until the late 1980s.

Today, Sloan farms 850 acres in Eastern Iowa, experimenting with strip-till and no-till techniques and, the past three years, cover-crops.

He’s also a member of the area’s Lime Creek Watershed Improvement Association.

“A lot of the people in the watershed group talked about how they remember how the stream was 40 years ago,” Sloan said.

“They say, ‘Wow, it’s never going to be what it was.’ I just hate to see a creek turn into a ditch.”

He has seen farms shift away from his father’s era of extended, diverse rotations of corn, oats and meadow — more perennials on the ground to prevent erosion and runoff.

Corn-soybean systems took over and nitrogen inputs increased steadily after the 1960s and plateaued in the 1980s.

Sloan and his farm neighbors were concerned for their creeks and for their valuable N and P investments.

Jamie Benning, Iowa State University Water Quality Program manager, said that’s where in-field and field edge conservation practices, such as modifying nutrient application, using no-till or cover crops or installing bioreactors come in.

“With the traditional corn-soybean system, we’ve evolved from very intense tillage. And now, as you drive across the state, you see higher use of no-till,” she said.

No-till has been around for several decades, and the concept of cover crops are an old idea researchers and farmers are trying to fit into an evolved system.

“Cover crops are a good example of a practice that’s been around for a long time and is being explored again,” Benning said.

“Putting in an additional crop for part of the season is not new, but we’re looking at it again for water and soil benefits, thinking through how to make it work in our current cropping system.”

Recent research points to better strategies for planting and terminating cover crops to maximize biomass production and reduce interference with the harvested crop.

Now, Benning and Sloan say it’s time for collaboration between ag scientists and farmers on a larger scale.

“We’re focusing education on conservation practices, helping farmers think through how to implement new practices and what they can expect for their particular farm and cropping system,” she said.

More-obscure practices are being tested.

Sloan installed an early biofilter. It worked for only a year, but the experiment helped move the technology forward.

A turning point in this water-quality history is this past year’s Nutrient Reduction Strategy. It’s the first program to put a number on ag-pollution reduction.

“This is a statewide look at conservation practices and how they perform in terms of reducing nitrogen and phosphorus — quantifying the impact of each practice,” Benning said.

Adam Schnieders, a senior environmental specialist with the Iowa DNR, said it’s going to be a long road.

“If it was easy to deal with nutrients, it would have been solved by now,” he said.

Nutrients are natural parts of all waters to a certain extent, unlike zinc, lead or mercury — the focus of other campaigns.

There are not standards that say X amount of phosphorus causes excessive algae blooms, Schnieders said. That depends on the depth and speed of a stream and amount of sunlight.

“We’d have to estimate numeric nutrient criteria,” Schnieders said, but with modern tools that imaginary number would be hard to achieve.

“While that may be the right number, it’s impossible and cost-prohibitive,” he added.

So, the first step to the future 45-percent reduction goal is determining baseline levels. Then, it could be 15-20 years of testing, implementing and adapting before all the groups involved see real results.

Copyright 2015 Iowa Farmer Today. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

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