Iowans’ Ideas: Guest columns featuring the views of different Iowans in each edition of Iowa Ideas magazine.
By Christopher S. Jones
Iowa’s most talked about water quality problem is stream nitrate pollution, and I spend roughly half my research hours studying the issue. The problem is not new and the drivers of it have been known for 50 years — fertilization and the altered hydrology of Iowa crop fields.
Google Scholar is a search engine researchers use to quickly scan the scholarly literature. “Iowa stream nitrate” generates 28,000 hits in Google Scholar, about 1,400 of which predate 1970.
Although I and others continue to study the details, the problem boils down to this: When the amount of nitrogen applied to fields exceeds crop needs, and that excess can find an easy pathway to the stream network, elevated levels of stream nitrate result. That pathway is usually tile drainage — networks of porous pipes used to lower the water table in the northern two-thirds of Iowa. In far northeast Iowa, nitrate also can quickly penetrate thin topsoil and enter streams through the porous limestone bedrock known as karst.
Iowa stream nitrate levels have increased approximately 10-fold over the past century and possibly a lot more than that in some rivers.
The nitrogen atom of the nitrate molecule may cycle through soil particles, bacteria, fungi, plants and animals multiple times over months or even years before entering a stream. Or less commonly, the applied commercial or manure fertilizer may directly enter a stream in the weeks or months after application.
In either case, the fundamentals remain much the same. We saturate the landscape with this water soluble nutrient and then in our haste to dry out the soil, provide it with a first-class ticket to the Missouri and Mississippi rivers.
The resulting stream nitrate impairs our drinking water, catalyzes nuisance and harmful algae blooms, and kills off part of the Gulf of Mexico when the Mississippi River unloads our baggage every summer.
Our government’s strategy to address this and many of the other negative environmental consequences related to agriculture has been to offer cost-share (public) money to entice farmers into adopting best management practices, or BMPs, thought to reduce the pollutant de jour. Every American that has ever lived since 1930 has contributed on average around $700 to farm conservation programs. There have been some successes, most notably with soil erosion, but thus far progress toward solving nitrogen pollution has been agonizingly slow, and in fact the problem may be getting worse. My own research shows nitrate loss in Iowa has increased more than 70 percent since 2003.
Iowa farmers can receive cost share funds for a variety of nitrate-reducing practices, including wetlands, saturated buffers, cover crops, wood chip bioreactors and others. Unlike BMPs for soil erosion, those designed to reduce nitrate loss offer the farmer very little or nothing in enhanced crop yields or farm value. In the absence of regulation, we are relying farmers’ altruistic instincts for BMP adoption.
What is the path forward to solving this problem?
In my view, there are a couple elephants in the room. One is the amount of fertilizer farmers are applying. Extra fertilizer is cheap insurance when it comes to growing corn. People who study these things know that, on average, farmers are applying nitrogen fertilizer well beyond the rates recommended by Iowa State University.
And this is before we consider nutrients excreted by livestock.
To give farmers license to apply however much fertilizer they want or feel they need, and then ask the public to pay for practices to trap the excess at the field’s edge with wetlands or bioreactors or whatever, is not a logical road map for water quality improvement.
To top it off, the taxpayer indemnifies the system with publicly supported crop insurance. Government policy helps keep fertilizer cheap, and government policy makes sure that the public shoulders the burden for the resultant pollution.
Elephant No. 2 is the group of individuals and companies that purchase commodity crops and benefit most from the super abundance of corn and soybeans and the low prices that come with that abundance. We ask nothing of them when it comes to water quality. This needs to change.
Most Iowa farmers are conducting their businesses as any rational person would do under the circumstances. They’re operating within a system that most of them had no part in creating and feel powerless to change. I think it’s unfair to farmers to expect them to solve this.
Going forward, we need to recognize this is a continental-scale problem and solutions will need to address complex socio-economic factors that cross state lines. There are very few problems of this scale and magnitude that have been solved through individual actions. Better water quality only will result if Iowa voters demand it, then hold their elected leaders accountable to the development of solutions that engage everyone benefiting from the exploitation of our natural resources.
• Christopher S. Jones is a research engineer in IIHR-Hydroscience and Engineering, in the College of Engineering at the University of Iowa.