Working to improve water quality in Iowa


Extension Demonstration Site Supplies Long-Term Data On Protecting Water Quality

Water quality continues to be a problem in Iowa that attracts statewide attention and a call for answers. Iowa State University Extension and Outreach’s Drainage Research and Demonstration Site near Gilmore City, Iowa, has played an important role for 25 years in supplying long-term information on how farm practices impact water quality.

In 1987 Iowa’s Groundwater Protection Act established fees on pesticide manufacturing registrations, pesticide dealer licensing and a tax on fertilizer sales. Three years later ISU Extension and Outreach, along with the Iowa Department of Agriculture and Land Stewardship (IDALS), the Iowa Department of Natural Resources (IDNR), and the Pocahontas County Soil and Water Conservation District, used a portion of those funds to create the 11-acre site in north central Iowa.
The purpose was originally to study agricultural drainage wells but later extended to investigate other factors that influence the movement of nitrates and herbicides into water from tile-drained farmland. “Every year the data becomes a bit more important because of all the issues we are facing in today’s agriculture,” said Stu Melvin, ISU professor emeritus and retired extension agricultural engineer, who was involved with the site from the beginning.
The Pocahontas County site is one of the oldest and most active drainage demonstrations in the country. Site director Matt Helmers, ISU professor and extension agricultural engineer in the Department of Agricultural and Biosystems Engineering, oversees experiments on 72 plots that compare crop rotations, tillage practices and cover crops to their effects on water quality. The site’s strength is its ability to look at nitrate loss under a wide range of weather conditions over numerous years, providing a picture of how precipitation impacts nitrate loss, Helmers said.
The research has revealed the amount of nitrate from nitrogen fertilizer applications leaching into tile lines from different crop rotations and tillage practices, specifically conventional and no-till. Nitrate concentrations in tile line water from continuous corn crops and from corn-soybean rotations have been similar, and the difference between fall and spring applications has not been proven to be significant. Nitrate loss exists whether or not fertilizer is applied although the rate of loss is impacted by the amount of nitrogen applied along with other key factors.
However, studies conducted from 2011 to 2015 have shown that cover crops can reduce the flow of nitrates into subsurface drainage. Cover crops have been shown to decrease nitrate loss as much as 25 percent at this site. Perhaps the most important recent finding from the data collected at the site is that nitrate loss to tile lines in farmland is primarily due to the lack of nitrate uptake by live plant roots in the fall and spring, and cover crops can counter this loss.
Extension staff have shared the results with thousands of Iowa farmers. Each year Iowa producers can attend a field day at the research site or hear Helmers present the findings at nearly 30 events throughout the state. The research conducted in north central Iowa reduces the risks that farmers associate with trying new practices and products because they can learn how they worked on the site before adopting them on their own farms.
Iowa Secretary of Agriculture Bill Northey, who owns a farm near Spirit Lake, spoke at the summer 2015 field day marking the site’s 25th anniversary. “Water quality concerns are motivating farmers to take action,” he said. Northey has adopted cover crops and no-till farming practices and also conducts nitrate water testing every spring.
The drainage research site has served another monumental purpose. Its decades-long studies acted as an aid to the team that developed the Iowa Nutrient Reduction Strategy.
This science-based initiative is part of a larger effort involving all 12 states that border the Mississippi River. In 2008, the Mississippi River/Gulf of Mexico Watershed Nutrient Task Force requested that the states institute plans to reduce the amount of nutrients released into their waters that ultimately contribute to a dead, oxygen-depleted zone in the Gulf. ISU Extension and Outreach worked with IDALS and IDNR to evaluate the knowledge gained from research sites such as Gilmore City in creating a statewide plan.
The drainage research and demonstration site will continue to provide Iowa farmers with further information to successfully manage their role as stewards for the state’s water, particularly on how to maximize the benefits from cover crops.
Northey expects that the work conducted in north central Iowa during the next two decades will determine the face of Iowa farming in the future. He anticipates that many farmers will adopt water quality practices that will make a significant environmental difference, not only for Iowa’s water, but for the entire nation.
With the knowledge garnered from the plots, farmers have learned the value of cover crops and alternative tillage, along with the importance of water testing. If a change in agricultural practices prevents nutrient loss at a select site, then the adoption of new techniques on their own farms will have a positive outcome for the bigger water quality picture.
For more information:
Matt Helmers, professor and extension agricultural engineer, 515-294-6717,
Jamie Benning, water quality program manager, 515-294-6038,

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