Life here on Earth has it all figured out. Plants consume carbon dioxide and water and pump out oxygen and carbohydrates. Animals consume carbohydrates and pump out carbon dioxide. It works beautifully when in balance. When out of balance, it creates spots where no life exists called Dead Zones. Dead Zone sound like something from a Stephen King novel. In reality, they are found in watersheds. The cause: lack of dissolved oxygen in the water.
Dissolved oxygen gets into water when it rushes and tumbles. How does it leave water? It gets used up by animals and by decomposition.
When fertilizer from fields runs into the water, it causes algae to grow.
No problem, right? The algae will put oxygen in the water. It does, until it dies or until the excess algae chokes out other vegetation and kills it. Decomposition uses oxygen. The oxygen levels fall and animals die due to the lack of it, just as in the Death Zone of Mt Everest where the lack of oxygen is due to lower air pressure. Just like Everest climbers, aquatic animals try to get to areas of higher oxygen…they try to swim away and also gulp air at the surface. But they become lethargic and eventually will suffocate.
Of all crops, corn uses the most fertilizer. Therefore, its production is responsible for most of the Dead Zone. This map shows where most of the fertilizer us used in the Mississippi. Because fertilizer is mostly nitrogen, phosphorus, and potassium, these areas are labeled “Nitrogen Hot Spots.”
The problem is acute when fresh water from farm fields containing fertilizer washes into the Mississippi. This water streams into the Gulf of Mexico-salt water–and sits on top of it because salt water is heavier.
Dissolved oxygen levels should be around 10 ppm for healthy water. Click here to check your local dissolved oxygen levels.
Sadly, the Dead Zone is projected to reach record levels this year, due to all of the flooding in the midwest.
What can be done to prevent this problem? One solution is to restore flood plains. No till farming and cover crops are other solutions.
Another is to follow the 4 Rs of nutrient stewardship.
- Right fertilizer source at the
- Right rate, at the
- Right time and in the
- Right place
However, crop farmers are not the only ones to blame for this. In fact, lots of the pollution comes from meat and dairy operations. Personally, I try to limit my meat and dairy consumption and when it comes to eggs and chicken, I buy local…but it’s not easy for me.
The Dead Zone and agricultural pollution is a huge issue for Iowa. Because of all the animal feeding operations, Iowa is number one in poop...and the excess nitrogen in the form of nitrates that comes with it. New evidence shows that this does more than cause the Gulf Dead Zone. It contributes to cancer, including thyroid cancer which is very common in Iowa, colorectal cancer, ovarian cancer, and many birth defects and pre-term birth. We need more regulations of these pollutants. We need to reduce our dependence on corn and corn ethanol in Iowa. We need more regulations on animal feeding operations–many of them are owned by China. Did you know that there is more chicken shit in Iowa than people shit? None of it has to go through sewage treatment! Not a pretty picture.
Solutions will not be easy and won’t come as long as Iowans are complacent about the issue. Last year, almost none of my students had even heard of the Dead Zone. Iowans consider themselves “Iowa Nice” because they are superficially polite. But being ignorant of pollution is not very nice, is it?
Sadly, all of this rain and flooding will be a disaster for water quality. Here is a great article with more information.