More drainage and water quality benefits, too? Maybe

Can more drainage paired with wetlands improve water quality and farmers’ profits? Let the research proceed, and until then, let’s withhold judgment.

Will Hoyer
Will Hoyer

We’ve all heard about the area of hypoxia, or the so-called “Dead Zone,” in the Gulf of Mexico. As a result of all the rain and flooding this year and the amount of water flowing down the Mississippi, scientists are expecting the Dead Zone to be the largest ever recorded.

It’s starting to appear that these rain events are becoming the “new normal” just as climate modelers have predicted. Therefore it is becoming even more imperative that we take steps to reduce the amount of nutrients that are leaving Iowa fields and keep them from flowing downstream. The Wetland and Drainage Initiative that we write about in our latest report is an attempt by the Iowa Department of Agriculture and Land Stewardship (IDALS) to study one potential way for doing just that.

At the heart of it the concept behind the Initiative, which some know as “the Iowa Plan,” is the idea that enlarging the subsurface drainage(or “tile”) capacity will allow fields to dry faster thus increasing crop yields. The additional profits from the higher yields could then pay for the construction of nitrate removal wetlands that would be built at the outlets of the tiles. The larger tile capacity would mean more nitrate leaving the fields but the nitrates would be removed by the wetlands. That’s the theory — but it needs to be tested. That’s what IDALS is doing, in partnership with other agencies and groups, at several sites in north central Iowa.

map showing Des Moines Lobe
The Des Moines Lobe is the focus of the IDALS initiative.

We really don’t know for sure if this Initiative will work as touted and there are lots of questions, questions that hopefully will be answered with rigorous, transparent monitoring of the pilot sites. Rightly or wrongly there is a lot of skepticism among some groups regarding anything IDALS does and so the onus is on IDALS to demonstrate that these pilot projects, were they to be expanded across the tile-drained parts of the state, would actually have water quality and crop yield benefits and would not have unintended negative consequences.

A lot of research underlies the Initiative, and with thorough monitoring of the pilot sites scientists will probably know a lot more in five years. It’s possible that these treatment wetlands will be playing a much bigger role in the next few decades in Iowa, Illinois and other tile drained parts of the country, but in five years the data may also show that the concept just does not work. We’ll see.

  • We should avoid a situation where farmers are putting in larger tiles with no way of removing the extra nitrogen and therefore contributing even more to downstream water problems.
  • We should avoid subsidizing farmers’ installations of larger tiles.
  • We should avoid draining the few remaining wetlands we have left.
  • We should avoid putting scarce public dollars into programs that may not have benefits.
  • We also should avoid putting all of our eggs in one basket. It’s going to take more than just these nitrate removal wetlands to get Iowa water quality to where it needs to be and there are lots of other steps that can be taken and existing programs that could use more resources in the meantime.

In short, this is a message to catch our breath and let the research tell us what’s happening. This Initiative combining enhanced drainage and nitrate-removal wetlands shows promise to benefit both farmers and water quality but until we see the numbers in a few years we will withhold judgment.

By Will Hoyer, Research Associate

Author: iowapolicypoints

The Iowa Policy Project is a nonprofit, nonpartisan organization that provides research and analysis to engage Iowans in state policy decisions. We focus on tax and busget issues, the Iowa economy, and energy and environmental policy. By providing a foundation of fact-based, objective research and engaging the public in an informed discussion of policy alternatives, IPP advances effective, accountable and fair government.

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