Fairfield, Iowa, farmer and soil scientist Francis Thicke wrote a response to an editorial on water quality published in the Des Moines Register.
Thicke said the June 28 editorial, by Iowa’s Secretary of Agriculture, Mike Naig, contained the “usual misinformation on nitrate put forth by the Farm Bureau and other ag groups.”
While the Register has not published Thicke’s editorial, here it is in full, below, followed by Naig’s:
Iowa Secretary of Agriculture, Mike Naig, in his June 28 Iowa View, presented us with the usual ag-lobby refrain that Iowa’s nitrate problem is caused by the weather. It is time for Iowa’s citizens to stop listening to this kind of misinformation and learn about the real cause of our nitrate problem, and how we can solve it.
High nitrate levels in Iowa’s rivers have one basic cause: our predominant cropping system—corn and soybeans—is fundamentally flawed. It is inherently leaky of nitrate. The reason it is inherently leaky is that corn and soybeans are annual crops that have live roots in the soil for only about five months of the year. During most of the year there are no live roots in the soil to remove and utilize the soluble nitrate that travels with rainfall down to field tile drainage systems and on to our rivers.
It is time to stop pretending that rain is the cause of our nitrate problem. Nitrate pollution of our rivers is inevitable under corn and soybean cropping systems without remedial conservation measures, such as the use of cover crops. And, since two-thirds of Iowa’s total land surface is covered with corn and soybeans, it should be no surprise that our rivers are polluted with nitrate. Yes, heavy rainfall events will increase nitrate leaching under some conditions, but heavy rainfall events are to be expected. It is disingenuous to blame our nitrate problem on the weather.
Iowa’s pattern of cropping systems is a water quality problem waiting to happen.
Research shows that perennial crops as well as cover crops that are planted to grow during the off season of corn and soybean production can dramatically reduce nitrate leaching and loss to our rivers because those crops provide roots in the ground during times when corn and soybeans are not growing. Those crops scavenge soil nitrate before it reaches the field tile drainage system. Unfortunately, only about two to three percent of Iowa’s cropland is planted to cover crops each year.
As the June 22 Register article by Donnelle Eller points out, “Nitrogen pollution flowing out of Iowa to the Gulf of Mexico has grown by close to 50 percent over nearly two decades…despite hundreds of millions of dollars spent to stem nutrients entering the state’s waterways.” Our investments are not paying off. We need a new approach.
There is one straightforward way to solve our water quality problem: require every farm in Iowa to implement a water quality plan that addresses the specific water quality concerns for each farm.
We now have sufficient water quality research data to be able to estimate the expected loss of nitrate and phosphorus from farm fields for various combinations of farming practices. Like with the Universal Soil Loss Equation—which predicts soil loss for various farming practices—we could use our water quality database to create a water quality computer model that will predict nitrate and phosphorus loss from any farm field based on the field’s cropping and conservation practices. That water quality model could be used to create farm-level water quality plans.
Farm water quality plans would allow every farmer the flexibility to choose farming and conservation practices that fit his or her farming operation, as long as each farm field met the tolerance levels for nitrate and phosphorus loss to our water resources. Tolerance levels for nitrate and phosphorus should be based on the statewide goals of Iowa’s Nutrient Reduction Strategy, which calls for Iowa agriculture to reduce nitrogen loss by 41% and phosphorus loss by 29%.
Iowa’s voluntary water quality approach is not working. A flexible, science-based regulatory approach—like a mandatory water quality plan for every farm—is needed to solve our water quality problems.
Francis Thicke, of Fairfield, is a farmer and soil scientist and has served as the National Program Leader for Soil Science for the USDA-Extension Service.
Five years ago, our Department of Agriculture partnered with Iowa State University, the Department of Natural Resources (DNR) and others to develop the Iowa Nutrient Reduction Strategy as a science-based model to guide our water quality efforts. Since that time, we have regularly reviewed the progress we’re making and identified ways to do even more to protect our natural resources.
Accurately measuring what’s happening in Iowa’s watersheds is complicated. We know – and numerous studies have shown – that many factors, such as soil type, landscape and weather can have a significant impact on surface water and nitrate levels.
Unfortunately, the water quality story in the June 24 edition of the Register focuses primarily on monitoring data and doesn’t address other key factors that must also be considered in water quality assessments. Even the authors of this current study, Chris Jones and Keith Schilling, conducted a study just three years ago that showed that weather is the highest correlation with nitrates, not farming. At the time, they told the Register that “nitrate trends can be tricky, subject to large swings brought on by drought or heavy rains.”
Additionally, a 2016 report prepared by the DNR in collaboration with our department, Iowa State and the IIHR Hydroscience and Engineering Center, also documented the impact that extreme rainfall events can have on both nitrogen and phosphorus loads into surface water. The report shows stream bed and bank erosion during those events contributed to fluctuations in nitrates and phosphorus and that “year to year variation in precipitation is likely the biggest factor in the variability of nutrient concentrations and loads and the main reason why measuring statistically significant trends in nutrients is difficult.”
When you test, where you test, and the weather at the time makes all the difference in measuring water. If we measure the rivers – especially now when we’re looking at widespread flooding – we see weather effects, rather than things farmers, landowners or cities can control. We can’t control the volatile weather we’re experiencing right now, but we can mitigate impacts to the landscape by the types and number of conservation practices implemented. This, along with long-term water monitoring, is a more accurate indicator of our progress.
While farmers and landowners are making great progress in soil conservation, we are just getting started in our quest to reduce nitrogen loss. Prior to the Iowa Nutrient Reduction Strategy being implemented five years ago, the primary focus of conservation for Iowa farmers was reducing soil erosion, not nitrates. Now, 90 percent of the funds through the Water Quality Initiative go to proven practices focused on reducing nitrogen loss.
Iowa has been a national leader in the development and implementation of nitrogen reduction conservation practices including wetlands, bioreactors and saturated buffers. Other states are using our strategy as a model because it is working and will work over the long term. I’m proud of our farmers and the incredible culture of conservation we’ve seen instilled since the implementation of the Nutrient Reduction Strategy. We are set to continue scaling up proven, science-based practices.
More than 250 partners are supporting 65 rural and urban demonstration projects across the state. We have brought in more than $38 million from partners to support the work, including a recently announced $1 million grant from EPA focused on conservation drainage practices to reduce nitrogen loss. The Nutrient Research Center at Iowa State is coordinating monitoring efforts and conducting research of additional practices that can help reduce nutrient levels.
Landowners and community members are embracing conservation practices and are committed to making a difference. This is a complex issue. Weather, timing, funding and implementing proven conservation practices are all important factors to consider. Yet, Iowans are embracing the challenge of improving water quality and will continue to do so. We have much more work to do, but we are headed in the right direction.
Mike Naig is Iowa’s Secretary of Agriculture.