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How the 2012 drought could lead to one of the largest Gulf of Mexico "Dead Zones" ever recorded

Claire O'Connor

Posted June 20, 2013 in Curbing Pollution

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It looks like this year’s “Dead Zone” in the Gulf of Mexico will be one for the record books.  Scientific experts predict that the annual, low-oxygen area that suffocates fish, shellfish, and other marine life will be one of the largest ever, reaching the size of the State of New Jersey. Oddly enough, the record-breaking 2012 drought, which had far-reaching effects on the farming community, the federal budget, and on grocery bills, can take most of the credit for the major water quality problems that cause the Dead Zone. 

When farmers planted in the spring of 2012, they had no way to predict that the hot, dry summer winds would shrivel up their crops.  So they purchased and applied nitrogen fertilizer as though the corn they planted would actually grow. Unfortunately, that was not the case. Most of the fertilizer farmers applied went unused. Though the deluge of spring rains the Midwest received in 2013 helped alleviate some drought conditions, most agricultural operations weren’t equipped to handle the moisture that came, and the rains ending up picking up the excess nitrogen and carrying it into local creeks and streams

In the Midwest, most of these creeks and streams eventually flow to the Mississippi River and empty into the Gulf of Mexico.  When the summer sun hits the nitrogen-laden water in the Gulf, the nitrogen fertilizer will encourage algae growth in the Gulf, just like it encourages corn growth in the Midwest.  The algae will grow at an unnatural pace, overtaking the Gulf and creating a dead zone by suffocating marine life. The local fishing- and tourism-dependent communities surrounding the Gulf will bear the brunt of this run-off, but water quality problems will occur throughout the Mississippi River basin.

 Mississippi Drainage Map.png

So how can we resolve this for the future?

Practices, such as cover cropping, can help. Cover crops are plants that are grown with the primary purpose of improving soil health, rather than for their cash value.  They can provide a variety of benefits, including beneficial habitat for pollinators, reduced erosion, improved moisture infiltration and retention on fields, and, most importantly in this case, nutrients that are held in place until commodity crops are ready to use them.

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For example, farmers can plant a cover crop mix that includes radishes after harvesting their typical commodity crops. Radishes’ tap roots soak up any unused nitrogen left in the field by the commodity crop, holding that nitrogen in place and preventing winter snows and spring rains from sending it downstream. Over the winter, these nitrogen-infused radishes will die and slowly decompose, leaving a nice pocket of nitrogen waiting for the spring crops.

Not only can this cover cropping method save farmers money on their fertilizer bills, but this practice can also play a role in preventing pollution problems downstream. As farmers move towards cover cropping, we will be able to see more predictable yields, financial stability, and reduced environmental tolls.

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Switchboard is the staff blog of the Natural Resources Defense Council, the nation’s most effective environmental group. For more about our work, including in-depth policy documents, action alerts and ways you can contribute, visit NRDC.org.

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