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.


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  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.”

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