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Keeping nitrates on the farm

By Staff | Feb 15, 2016

DR. MATT HELMERS, an Iowa State University agriculture and biosystems engineer, discusses farm-related water quality issues Feb. 4 with members of the ag committee for the Greater Fort Dodge Growth Alliance in Fort Dodge. Helmers provided an overview of water quality challenges associated with farming, and efforts to keep nitrates and phosphorus from reaching surface waters.



FORT DODGE – In a perfect world, food-producing farms would mimic nature’s sustainable ways and surface water would be running clear and potable, carrying small amounts of nitrates that happen naturally.

But things aren’t perfect.

In fact, agriculture’s presence alters nature, subsequently changing the environment.

Farms install tiles to drain excess water from the soil profile so field work like planting, fertilizing, spraying and harvesting can be done in a timely manner.

Humans and livestock need the food and products that grain crops provide. Tiling helps make it happen.

But rain events cause water to flow through the soil profile, flushing nitrates as it goes. The nitrate-ladened water enters tile lines which discharge into surface water.

The water continues downstream until it’s either trapped in a denitrification feature, like a wetland or an ox-bow lake, or it reaches the Gulf of Mexico.

And therein lies the problem.

There aren’t enough practices being used by Iowa farmers to keep excessive amounts of nitrates – 10 parts per million or more – from reaching surface waters and rushing off downstream.

Dr. Matt Helmers, an Iowa State University agriculture and biosystems engineer, spoke with members of the ag committee of the Greater Fort Dodge Growth Alliance Feb. 4, outlining the challenges of farming’s impact of grain farming on water quality and land management practices designed to keep nutrients in the field.

Cover crops, reduced tillage, controlled drainage and edge-of-field practices are all designed to help Iowa meet its obligations of the Iowa Nutrient Reduction Strategy – reducing by 45 percent the nutrient load in waters that leave Iowa and flow to the Gulf.

The practices are diverse, Helmers said, but the process of implementing them are complicated, namely in funding new land management practices, as well as changing the mindset of farm families, many of whom have been farming conventionally for decades.

Don Sandell, who farms near Burnside, said he wants to see Bill Northey, Iowa’s secretary of agriculture, stop telling farmers what a great job they are doing with conservation.

“A few of them are,” Sandell said, but added that many more are not.

Silver buckshot

In a December 2014 drainage school in Stanhope, Helmers told farmers there is no silver bullet in keeping nutrient loads from reaching surface waters.

“But we do have silver buckshot,” he said.

In Fort Dodge, Helmers acknowledged that the hard sell to farmers concerning nitrate-holding practices is the cost of implementing them.

These include:

  • Cover crops: In Iowa the best-suited plant is cereal rye, which grows quickly, sequesters nitrates in its cells, with an extensive root mass that holds soil in place and adds organic matter when it decomposes.

“We’re trying to mimic nature,” Helmers said, relating to Iowa’s pre-settlement prairie days.

He said cover crops also mimic the impact on soil as small grains did in Iowa 70 years ago.

  • Bioreactors: These are underground pits filled with wood chips. Tile water is channeled into the bioreactors. As it flows through the wood chips, bacteria feeds on the bulk of the nitrates before the water flows out and into a nearby waterway.
  • Wetlands: These are shallow, marshy areas with heavy, dense soil. They capture water and hold it in place to give prairie and marsh grasses a chance to take up nitrates and phosphorus before the nutrients reach a stream or creek.
  • Saturated buffers: These are underground. Tile water is directed to flow and be stopped temporarily under buffer strips, whose plant roots capture nitrates, keeping them out of waterways.
  • Controlled drainage: These are practices best suited for relatively flat fields, where tile water is allowed to discharge for a limited time, then gates on the lines are shut, holding the water in the system. The system can then be used as underground irrigation, keeping water rich in nitrates in reserve to feed plants in drier times.

“Just to 20 percent of nutrient removable in all of Iowa’s cropped acres,” Helmers said, “it would require 7,600 wetlands, or 120,000 bioreactors.”

To meet Iowa’s 45 percent reduction goal, Helmers said, it would require Iowa farmers to plant 12 million acres of cover crops. In 2015, Iowa farmers planted a record number cover crops at 500,000 acres.

“The problem is that none of these practices add to a farm’s short-term profitability,” Helmers said.

It will take a long time to get all the needed practices in place, he said, and that includes convincing farm families they must change their farming methods to meet the INRS goals.

“We have an alternative,” Helmers said, “and that’s to do nothing.”

But inaction, he said, will lead to federal and/or state agencies telling Iowans how they will management their farms.

It could also lead to more lawsuits like the one filed in early 2015 by the Des Moines Water Works against 10 drainage districts in three northern Iowa counties.

Economic boon?

Helmers said the long-term growth of using nitrate-holding practices can be boon for those who can site and design bioreactors, controlled drainage, saturated buffers and wetlands, as well as land improvement contractors to install them.

Growing cover crops for seed sales can also be a niche market for some farmers, he said.

“And all those funds would be kept within the state,” he said.

However, he left no doubt that to make it all happen, public funds will have to be available for farmers, whether as grants, cost-share, or low-interest loans.


Want to build a wetland? There are funds available



FORT DODGE – Dr. Matt Helmers, an Iowa State University agriculture and biosystems engineer, told members of the ag committee of the Greater Fort Dodge Growth Alliance Feb. 4 that of all the practices available for keeping field nutrients from reaching surface waters, he favors wetlands.

These are shallow, marshy areas with heavy, dense soil. They capture water and hold it in place to give prairie and marsh grasses a chance to take up nitrates and phosphorus before the nutrients reach a stream or creek.

He said wetlands were filtering nitrates from ground and subsurface water for centuries before modern settlement brought agriculture to break prairie sod and drain the marshes so food crops could be grown.

If considering re-establishing a wetland, Helmers said, “the first thing you do is get down to the NRCS office and get a wetland determination.”

Bob Moser, district conservationist at the Natural Resources and Conservation Service in Webster County, said his office will assist farmers and the Farm Service Agency in technical support in re-establishing a wetland that had been drained, or obtaining permanent wetland easements in fields that are prone to flooding.

Moser said the federal Environmental Quality Incentives Program has cost-share dollars available for establishing wetlands.

The Conservation Reserve Program also has a wetland component, he said, through FSA.

“And we will help FSA with technical support,” Moser said.

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