Are golf courses contributing to Iowa's nitrate runoff?
Iowa survey shows they don't contribute significantly
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Golf courses, with their manicured greens and lush fairways, have been cited as possible contributors of nitrate from fertilizer flowing from Iowa down the Mississippi River to an expanding oxygen-deprived dead zone in the Gulf of Mexico.
“The concept is our grass is so green and beautiful, they think we’ve got to be polluting the streams,” said Chauncey Barry, superintendent at the Twin Pines Golf Course in Cedar Rapids. “We’ve always had a bull’s-eye on our back.”
But a two-year study led by Keith Schilling, a research engineer for the Iowa Geological Survey, found Iowa golf courses add very little to Iowa’s total nitrogen load and actually have lower levels of nitrate in groundwater and surface water than other areas, including nearby private wells.
Because the randomized study showed similar results across the state, Schilling said the study applies to all Midwestern golf courses on glaciated terrain.
In the study, funded by Iowa and national golf and turf grass groups, Schilling and Matthew Streeter, a soil scientist, assigned each of Iowa’s 421 golf courses a number, then used a computer to randomly select one nine-hole course and one 18-hole course from each of three regions of the state: eastern, central and western.
At each of those six courses, whose superintendents agreed to be part of the study, the team drilled three wells — one each at tee, fairway and rough locations. The depth to the water table varied from 6.5 feet to 18.7 feet depending on the course.
“We drove a drill rig on their course and installed a well in a managed fairway or tee box, so this was no small approval on their part,” Schilling said. Two courses initially chosen at random declined to participate.
Water samples were taken from the wells eight times in 2015 and 2016. The team tested on site for temperature, specific conductance pH and dissolved oxygen. They submitted the samples to the State Hygienic Laboratory in Iowa City for analysis of nitrate and dissolved phosphorus — chemical nutrients fingered for creating Gulf of Mexico algae blooms that deplete oxygen.
The Gulf dead zone was the largest ever in measurements taken over the summer, according to the National Oceanic and Atmospheric Administration.
Schilling’s team also tested surface water, including streams, ponds or drainage tile discharge, present at the golf courses in this study.
“The average concentration at all the courses (in the study) was two milligrams per liter, which is very low,” Schilling said. “Three of the six courses did not have any detectable nitrate in shallow groundwater.”
One course in western Iowa had one well that averaged nearly 15 milligrams of nitrate per liter, an anomaly researchers believe might be connected to the thick loess soil deposits in that area still reflecting older turf-management practices.
The nitrate loads from the golf courses in the study were one-tenth of those measured in their watersheds, showing the bulk of nitrate polluting water is coming from other sources. All of Iowa’s golf courses combined contribute about .019 percent of the total nitrate load coming from Iowa, study estimates show.
Phosphorus measurements at the golf courses were on par with other parts of the state.
Golf course superintendents apply an average of 40 pounds of fertilizers per acre, Schilling said, compared to an average 150 pounds per acre for most agricultural operations.
Barry said golf superintendents consider course turf to be a year-round cover crop that prevents soil erosion and fertilizer runoff — possibly even purifying groundwater. “I’m not saying the ag guys don’t do a great job, but they don’t have a cover crop,” he said.
Schilling presented his study earlier this week to the Iowa Environmental Protection Commission, a nine-person board that provides policy oversight of Iowa’s environmental protection efforts. One member, Joe Riding, owns and manages Terrace Hills Golf Course, in Altoona, where the board met.
“Every facility I know, people are doing their best to reduce the impact on the environment,” Riding told The Gazette Thursday. “Ten years ago, our fertilizer budget was $60,000. Today, it’s $15,000. Economically, it also helps our bottom line.”
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