Midwest farm drainage key cause of Gulf of Mexico dead zones

The tile drainage systems in upper Mississippi farmlands — from southwest Minnesota to across Iowa, Illinois, Indiana and Ohio — are the biggest contributors of nitrogen runoff into the Gulf of Mexico, reports a Cornell/University of Illinois-Urbana study.

Nitrogen runoff has been identified as a major contributor to dead zones in the Gulf, where nitrogen fertilizes algae and causes it to bloom, which in turn, depletes oxygen from the water and suffocates other life forms over thousands of square miles each summer.

Tile drainage has greatly increased yields in fertile soils since the 1800s where there once were wetlands. The systems consist of burying perforated pipes under the soil and draining them into canals. When such fields are fertilized, more nitrogen runs off into the Mississippi River watershed, according to the study…

To reduce such runoff, solutions include installing wetlands in areas where tiles drain to biofilter the water and fertilizing fields in the spring instead of the fall. Also, “we know that we are losing nitrogen in the period between cash crops when nothing is growing in the field,” said Laurie Drinkwater. “If we plant winter cover crops and diversify crop rotations, nitrogen losses could be reduced quite a lot.” A 2006 study by Drinkwater’s research group found that, on average, cover crops reduced nitrogen leaching by 70 percent.

Drinkwater added that policymakers need to increase incentives that reward environmentally beneficial farming practices. Currently, direct payments to farmers focus on production outcomes and do not sufficiently emphasize environmental stewardship, she added.

Ain’t she polite?

I’d be hard-pressed to think of any avenue of money between the government and productive enterprise – agricultural, industrial or otherwise – that cared for little else other than profit.

4 comments

  1. Pingback: Tweets that mention Midwest farm drainage key cause of Gulf of Mexico dead zones « Eideard -- Topsy.com
  2. Behind the scenes

    “Reexamining the Ag Exemption” http://www.stormh2o.com/SW/Articles/Reexamining_the_Ag_Exemption_27020.aspx “…Many urban stormwater managers feel their programs’ incremental and costly efforts are undermined by unregulated ag discharge. An often-cited example is the dead zones in the Gulf of Mexico and elsewhere; the one in the Gulf this year is about the size of Connecticut, and that’s an improvement from previous years. Researchers have shown that the source of most of the nutrients causing the dead zones is agricultural runoff. Compared to that, a city’s illicit discharge detection and elimination program, no matter how successful, can seem a paltry undertaking. StormCon this past August in Portland included a program update and Q&A session with representatives from EPA. One question from the audience – it comes up almost every year in some form – was “Why isn’t runoff from agricultural land regulated in the same way urban stormwater runoff is?” The EPA folks, understandably, declined to give a detailed answer, though one of them did say it would take an act of Congress for things to change.”

  3. Proud Mary

    “A model approach for sustainable phosphorus recovery from wastewater” https://www.agronomy.org/science-news/model-approach-sustainable-phosphorus-recovery-wastewater “…Whatever phosphorus we use and discharge into rivers and oceans is lost to the environment,” says Rolf Halden, professor at the School of Sustainable Engineering and the Built Environment, and director of the Center for Environmental Security, Arizona State University.
    Additionally, accumulation of phosphorus can result in problems like algae blooms in lakes and other surface water bodies. In turn, algae blooms deplete oxygen from the water, affecting the delicate balance of aquatic life. “This problem is observed in the seasonally recurring ‘dead zone’ of the Gulf of Mexico,” says Halden.
    …Conventional methods remove only 40%-50% of P, according to (the study’s lead author Arjun) Venkatesan. The secondary treatment of sludge employed by EBPR (Enhanced biological phosphorus removal http://en.wikipedia.org/wiki/Enhanced_biological_phosphorus_removal ) “achieves an additional 35% mass reduction, for a total of about 90% removal,” he says. EBPR helpfully avoids additional chemicals and reduces sludge production. Both these factors lower the cost of operation–a key consideration for WWTPs (wastewater treatment plants) with limited budgets.
    Reclaimed phosphorus pays off for the environment with less mining for phosphorus and improved surface water health. phosphorus recovered as struvite {http://en.wikipedia.org/wiki/Struvite } can also generate income. The team estimates that the WWTP used in their case study could generate $150,000 in annual revenue from this two-pronged approach. A plant with existing EBFR facilities can recoup the initial expenses in as little as 3 years.”

  4. M23

    “Wetlands continue to reduce nitrates” http://news.aces.illinois.edu/news/wetlands-continue-reduce-nitrates “Wetlands created 20 years ago between tile-drained agricultural fields and the Embarras River were recently revisited for a new two-year University of Illinois research project. Results show an overall 62 percent nitrate removal rate and little emission of nitrous oxide, a potent greenhouse gas. “Slowing down the rate of flow of the water by intercepting it in the wetland is what helps to remove the nitrate,” says Mark David, a University of Illinois biogeochemist in the College of Agricultural, Consumer and Environmental Sciences. “The vegetation that grows in the wetland doesn’t make much of a difference because the grasses don’t take up much nitrogen. It’s just about slowing the water down and allowing the microbes in the sediment to eliminate the nitrate. It goes back into the air as harmless nitrogen gas. ….”No one wants to mandate a certain practice — wetlands, bioreactors, cover crops, adjusting the timing of applying fertilizer-all of these things that we know help reduce nutrient loss. But, because of this research, we know that wetlands are a long-term nitrate removal method that keeps on working with little greenhouse gas emission. By building a wetland, farmers have an opportunity to make a substantial nitrate reduction in the transport of nitrate from their fields to the Gulf.” Mark David, a University of Illinois biogeochemist in the College of Agricultural, Consumer and Environmental Sciences. See also http://en.wikipedia.org/wiki/Biogeochemistry

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