It’s good to see a big Midwest “land grant” agricultural program that’s concerned about the Gulf Dead Zone, and upper Midwest farms’ large contribution to it. But this release about a study underway at Iowa State University aiming to reduce nitrogen entering the Mississippi River from farm fields falls flat when you realize it’s just a technical fix for the status quo of over-fertilized conventional commodity crops.
Half of the nitrogen that makes it to the Gulf is from commercial fertilizer, and 15 percent is from livestock manure. The rest comes from wastewater treatment plants, industry, and rainfall, according to the U.S. Geological Society.
As much as 39 percent of the nitrogen buildup in the Gulf has been traced back to the Upper Mississippi River Basin, including Iowa.
So what is a bioreactor and how can it help? From the Iowa state page:
A bioreactor is a large trench through which water from underground drainage tiles passes before leaving the field. This hole or trench is filled with organic matter that is high in carbon, in this case a mix of chips from various hardwoods, that act as a strainer for water coming from the tile. The wood chips “strain-off” nitrogen (appearing as nitrates) in the water by growing bacteria that digest the nitrates before the water flows out of the field and into nearby streams
While the pilot bioreactors are only about 12 square feet in surface area, full-scale bioreactors require about 25 square feet per acre of farmland drained and a depth of about four feet depending on the location of the tile line. A 100-acre field would require about 2,500 square feet of bioreactor space covered by a grass buffer.
Sounds expensive! And, uh, like a lot of digging. Add in all the plastic “tile” tubing that’s buried in the fields to drain the fertilizer (and all attendant pesticides one would assume) off quickly and into watercourses, now it’s sounding pretty wasteful. And toxic.
Organic methods of reducing such runoff would necessitate a whole different system that would by default radically limit nitrogen and pesticide pollution of the rivers, and would institute weed management techniques like crop rotation and cultivation that could be the region’s only defense against herbicide resistant GMO superweeds which are well established in the South and marching northwards.
So how about putting more funds, effort, and multi-year studies toward getting conventional farmers off of chemicals altogether, instead of building enough trenches to hide an army?
Get Grist in your inbox