Hypoxia and Nutrient Management

We have been hearing about hypoxia, or the so-called dead zone in the Gulf of Mexico since it was first documented in 1972.  Environmentalists continue to push for a size reduction in the size of the hypoxia zone, and agriculture gets the blame for most of the problem.  This NOAA study indicates that they believe that 74% of the nitrogen load is from agriculture.  This Prairie Farmer article indicates that progress in addressing hypoxia is slow even after a 2008 plan was written to address the problem. 

This study out of Texas A and M University suggest that 25% of nitrogen in the "dead zone" is from corn and soybean production, and yet there are a lot of fingers pointing in that direction.  The main culprit is thought to be tile drainage.  A good bit of science has gone into how we can reduce nitrogen loads in tile water discharges.  Why does the nitrogen escape in our tile water?  One big reason is fall application of nitrogen.  Weather is also a big contributor.  Nitrogen losses are much higher in wet weather.  The companion article to the one above goes into particulars about nutrient loss and tile drainage.  the sidebar on that page lists best management practices that can reduce nitrogen discharges in tile water.

I would maintain that tile drainage can actually help reduce the problem in some cases because drier soils will not lose as much nitrogen.  Having said that, we still need to look to ways to make our nitrogen fertilizer more efficient and reduce losses even further.  It will be interesting to see if agriculture can work toward reducing discharges to avoid regulation.