Water Quality — Everyone’s Responsibility?
Farmer Brian Scott turns to look over his shoulder at the 60-foot wide, 24-row corn planter as it rolls through the field. Soon, however, Scott’s eyes settle back on a computer screen in the tractor cab. The screen shows a digital map of the route he set up for the tractor to follow through the field. Even though he sits in the driver’s seat, Scott will quickly tell you that most of his equipment basically drives itself. He believes in precision agriculture, from GPS-based yield and application maps to smart tractors. “I’m all about the latest and greatest in ag tech,” Scott says.
Another example of precision agriculture: Scott uses variable rate technology (VRT) to apply fertilizer, based on soil tests he conducts on a third of his fields each year. The data are used to create maps showing the optimum fertilizer rate for each zone. It’s an efficient method that closely matches the need for fertilizer to the amount applied. For corn, Scott also uses a split application schedule, applying part of the fertilizer in the fall or early spring before the corn is planted, and the remainder after the corn emerges, when it needs nitrogen the most. He believes the split application helps prevent the fertilizer from leaching into the groundwater and ultimately will save him money from over-application.
Agriculture these days is a high-tech business. Farmers like Scott use technology to boost yields and profits, and potentially to manage environmental issues as well. But 2013, which brought floods to Iowa followed by a drought, also delivered a record pulse of nitrogen from the Midwest into the Mississippi River and ultimately the Gulf of Mexico.
So What’s Going On Here?
IIHR Assistant Research Engineer Adam Ward studies how water and pollutants, such as nutrients, pharmaceuticals, nanoparticles, and more, are transported through the landscape and eventually into our streams and rivers. Ward, who is also an assistant professor in the University of Iowa Department of Earth & Environmental Sciences, is interested in where contaminants enter the natural system, how they move through and between streams, wetlands, and aquifers, and how we can better manage for or clean up these contaminants.
“I’m a stream-hugger, to coin a phrase,” Ward says. Iowa in particular, he says, faces major water-quality and quantity challenges — addressing these challenges will mean balancing our actions on the landscape with sustainable resource management. Given the efforts to make fertilizer use more efficient, Ward wants to understand why we have large nitrogen pulses like the one recorded in 2013.
Weather plays a major role. In a drought year such as 2012, plants don’t use as much water and nitrogen to grow, resulting in smaller yields. Fertilizer applied in the spring, with hopes for ideal rainfall and a bumper crop, lingers in the soil through the growing season and on into the winter. Spring rains the next year mobilize the nitrogen, sending it downstream in large amounts. The drought of 2012, followed by a wet spring in 2013, made this year’s pulse worse and moved a lot of nitrate very quickly, Ward explains.
He explains that crop yields are controlled by nutrient availability and weather. We control nutrients through crop rotation, soil conservation practices, and fertilizer application. Farmers apply fertilizer strategically in anticipation of what they hope will be ideal weather conditions. But when we draw less than ideal weather, there are economic and environmental consequences.
Ward is quick to point out that farmers are not the bad guys in this scenario. Farmers and land managers are stewards of important natural resources, and of our food system, he explains. “I don’t know of a single land manager whose aim is nutrient runoff — farmers recognize the economic and environmental costs of nutrient loss.”
Whose Fault Is It, Then?
We all get a share of the blame, Ward says, because we all benefit from the cheap and plentiful food provided by our current food system, which he says is largely subsidized by nitrogen fertilizer.
Ward says he wants to help Iowans connect the dots to see how actions on the landscape have environmental, economic, and social consequences. He hopes to help inform Iowans on how climate and human systems interact, so we can more sustainably manage water resources.
Ward’s focus is on how water moves through the landscape, ranging from where the raindrop first touches the ground, through the soil column, into the groundwater, and eventually into the stream network. He asks questions such as: How much water is moving through different locations on the landscape? How long does the water spend in any one place? What contaminants move with the water? What are the ecological costs or benefits associated with this transport?
Ward says there are both “hot spots” and “hot moments” on the landscape. Hot spots are locations where a desired process, such as nitrogen removal, occurs at a high rate. Hot moments are times when these processes turn on at certain locations for a short while.
We need to match the pollutant source with the hot spots and moments in the system, Ward explains. For example, if wetlands are hot spots for nitrate removal, but those wetlands are the most efficient in the late summer, their capacity for nitrate removal might not be well matched with peak nitrate loading, which occurred in early spring in 2013. Ward says he hopes to work toward management practices in which nitrate loads and efficient removal are well-synchronized in the system.
“It’s a matter of identifying the right combination of infrastructure and management to meet multiple objectives,” Ward explains.
Ward and several of his colleagues in the University of Iowa’s Water Sustainability Initiative (WSI) recently applied for a National Science Foundation grant to study the environmental, political, and economic impacts of land management decisions, and the information used to make those decisions. Where does the information supporting decision-making come from? Who could influence land managers to take a second look at their practices?
Being a member of WSI helps build an effective, diverse team very quickly, Ward says. “It lets me think about problems a little differently, because I know I have a team of experts who are excited about these interdisciplinary issues.”
In his research, Ward uses field monitoring to understand how water and solutes move through the system, and numerical modeling to test the variables, whether related to the science or to human decision-making. This combination of observations and modeling allows him to make projections of what might happen in the future. Field monitoring helps us understand the current situation, Ward explains. Numerical modeling allows us to rapidly explore a range of potential futures, and to understand the trade-offs between actions and outcomes.
Ward hopes that with good science and strong leadership, Iowa can become a leader in water quality. “I would love to see Iowa take a leadership role in balancing social, economic, and environmental outcomes of our management activities,” he says. Land management decisions, even the status quo, represent trade-offs between these outcomes. Ward hopes his research can inform decision-makers, ranging from individual farmers to policy-makers.
Midwestern farmers definitely have a keen interest in the research conducted by Ward and his colleagues. “The bottom line is, if I can lose or use less nitrogen, I ought to make more money,” farmer Brian Scott explains. And if less nitrogen leaches into the groundwater, it’s good for everyone downstream who drinks or uses the water.