A Plan to Reduce the Size of the Dead Zone

This week I received an email from a representative of Landscape Architecture Magazine to inform me about their November 2012 issue which features a cover story titled, “The Dead Zone Starts (or Stops) Here” by Anne Raver. I read the article from this quality publication and it is superbly written and the study has a lot of merit about a subject which is mostly swept under the rug by our nation’s citizens and its politicians. I strongly endorse the plan that University of Illinois ecologist David Kovacic is proposing in this article. I might argue that there would be other policy measures which would be prudent to also address the problem, but mine would be far less politically palatable than his.

This article deserves a lot of attention and promotion, so I encourage readers to pay the $5.25 to access the entire month’s magazine through zinio or find a hard copy at your Barnes and Noble or local bookstore if you are lucky enough to have one. To follow, I am offering a few highlights from the article and of Kovacic’s plan.


The cover of the issue pictures David Kovacic next to a tiling machine:

Many parts of Illinois and Iowa were wetlands before this country was settled. Only through the use of tile drainage systems can this land be farmed and now it produces 31 percent of the world’s corn and 35 percent of its soybeans. Due to current agricultural policy promoting corn demand and reimbursement, this land is being intensively farmed up to every possible edge.

Farmers apply nitrogen fertilizer which is highly soluble and leaches into the shallow water tables where it travels through tile systems into nearby waterways, eventually exiting through the Mississippi River and creating a huge hypoxic dead zone in the Gulf of Mexico. Iowa and Illinois contribute 35 percent of these nitrates, but Ohio, Indiana, Minnesota, Michigan, Wisconsin, and Missouri also contribute. Not only does this affect the Gulf, it affects the region’s lakes and rivers.

The article includes a nice background on the rich soils and the original ecosystem of this industrialized agricultural region, but I was disappointed that it didn’t mention soil run off as being a huge related problem, my only quip with the article. Nitrogen and phosphorous enter the river through upstream runoff of fertilizers, soil erosion, animal wastes, and sewage.

Kovacic has worked for 20 years with Illinois farmers testing his idea that the re-creation of area wetlands can be used to mitigate the water pollutants which create the dead zone.

“His research shows that farmers could cut the nitrates flowing from their tiled fields by close to 50 percent if they constructed wetlands on a mere 2.5 percent to 3 percent of that land. Doing so would not only cleanse local watersheds and alleviate dead zones but would also reduce atmospheric nitrous oxide, a by-product of nitrogen fertilizer. “Nitrous oxide is a greenhouse gas with a global warming potential 300 times worse than CO2, and a major depleter of ozone,” says Kovacic.”

Next, is one of the significant points of Kovacic’s findings. He found that if existing buffer strips are in tiled areas, they don’t help much in mitigating agricultural water pollutants. Buffer strips are grass, shrubs or treed areas which serve to absorb water runoff and can provide an oasis of wildlife habitat on the edges of streams, rivers or low lying fields. Although federal and state agencies have encouraged farmers to plant buffer zones of grasses or trees and reduce nutrient applications, in the tile-drained farmland areas, the tiles carry the nitrates directly to the streams, bypassing the buffer strips where plant uptake and microbial transformation would otherwise do much to reduce them.

Part of Kovacic’s plan is to use the invasive reed canarygrass to uptake phosphorus fertilizers which are by nature sedimentary. He believes that it could sequester up to 30 pounds of phosphorus per acre.

If the rate of flooding from more extreme weather events continues to increase, his wetlands proposal might have economic value which would be an adoption incentive to farmers. He believes that wetlands built in these watersheds could reduce the peak impact of a 100-year storm by 25 percent.

Tiling 100 yards once took 10 men a week. Now two can do it in 10 minutes.

According to Kovacic’s research, it took 10 men one week to dig and lay 100 yards of clay tiles end to end — to funnel the water to the nearest stream or river, having to dig four to six feet deep in muck. He marvels at the tenacity it took as they completely tiled the Midwest in 50 years, or to put it another way, “destroyed an ecosystem in 50 years”. Today’s tiling machines are fully computerized with GPS detailing.

In many ways, building wetlands on this destroyed prairie seems like going backward to farmers whose ancestors broke their backs to drain them.

Kovacic sympathizes with the farmer who is blamed for the runoff and recognizes that they are trying to do their best. They don’t want to lose money by taking even a few acres out of production when corn and beans are bringing such a high price. The ethanol craze has increased the cost of the farmland and the profits to be made off today’s productive acre which is privately owned. “The government might be willing to pay for wetlands, but is it willing to pay you $26,000 for two acres?” he asks.

He mentions as background to today’s farming practices, “Extension agents at land-grant universities have long told farmers what to plant, what kinds of fertilizers and pesticides to use, and how much, and they have historically been funded by chemical companies.”

Kovacic figures that the Midwest needs to convert a million acres of tile-drained cropland to wetlands to reduce hypoxia in the Gulf.

The ideal size of a cleansing wetland seems to be about 2.5 percent of drained cropland.

He estimates that $30 billion would cover construction costs and payments for permanent easements which could be amortized over 30 years. This could mitigate the whole Mississippi River basin and reduce loading in the Gulf by 45 percent.

5 thoughts on “A Plan to Reduce the Size of the Dead Zone

  1. Jardinero1

    Thanks for this post. Agricultural runoff is a pet peeve of mine, especially given the relative free pass it gets compared to pollutants from oil companies and refiners.

  2. packfan

    if taking out that 1 million acres of farm land will go a long way towards restoring up to 4 million acres of the gulf to a productive state I’d think that would be a very good trade. And I’m a farmer who really doesn’t like seafood. I do realize the sea is just as important to feeding the world as iowa farmland

  3. ecological gardening

    Excellent information, and timely for me as I have been discussing with a geographer how perhaps the historic destruction of Illinois wetlands could have possibly exacerbated the effects this summer’s drought. More wetlands (say, a million acres) might have had something of a mitigating effect, even if slight. And help reduce the dead zone? Win-win.

    My only quibble: reed canary grass? Really? Surely there’s some native species that while perhaps not quite as effective at taking up phosphorus would not be a scourge — here in the Chicago region it’s a real challenge when managing (let alone restoring) mesic-wet prairie areas and riverine sedge habitats.


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