Saturated Buffers: Not Your Average Vegetation Strip

By: Claire Hinther, St. Olaf College '19

Last summer, I began researching nitrogen abatement from saturated buffers on David Legvold’s farm in Northfield, MN. Dave is widely recognized as an advocate for sustainable farming practices and water quality awareness. He has been no-till farming for over twenty years and partners with researchers on projects that analyze pollution mitigation.

Saturated buffers are engineered strips of lands that artificially raise the water table and laterally redirect runoff to increase water storage and filtration. Watch the short video to better understand how they work.

 Saturated Buffer on Legvold's Farm in Northfield, MN.

Saturated Buffer on Legvold's Farm in Northfield, MN.

Partnering with the Minnesota Department of Agriculture, I installed a series of wells throughout the buffer in order to collect and test water samples. We also planted three separate transects with different native plants to analyze the impact of different vegetative covers in buffers aside from traditional shallow-rooted grasses. (See Claire’s previous installment of Conservation Farming: A Summer of Research, Digging In, Baseline Samples, Heavy RainsSampling Results )

This summer, I am continuing nitrogen abatement research in collaboration with Ecosystem Services Exchange, a company focused on conservation-based practices in water management. We are sampling water on the saturated buffer on the Legvold farm and another near Dodge Center in southern Minnesota.

In addition to water sampling, we will be exploring the factors that cause blockages in the distribution line—an underground pipe that redirects runoff throughout the buffer for storage and infiltration. Last year, the research group realized that the distribution line was susceptible to blockages from root penetration.

To explore this concern, we will plant a set of seed mixes—developed by the Minnesota Department of Agriculture—over the distribution line of the saturated buffer. After the grass has had time to establish, cameras will be sent through the distribution line to detect any blockages and assess which seed mix is least likely to compromise saturated buffer function.

I will also be assisting Laura Bender, Ph.D. Candidate from the University of MN, prepare a study site to analyze the impact of native prairie endomycorrhizal fungi (NPEF) as a strategy for bioremediation and removal of dissolved phosphorus from agricultural runoff.

To do so, we will plant a section of a saturated buffer with different mixes of prairie vegetation that include NPEF. Later, vegetation will be harvested and the plant matter from each mix will be used to measure phosphorus content and plant biomass. Water samples will also be drawn and tested for phosphorus concentrations. I will make myself available throughout the research process.

I am excited to continue with updates as all of these projects develop over the course of the summer.

 Alternative vegetation options plated along a saturated buffer at the Legvold Farm.

Alternative vegetation options plated along a saturated buffer at the Legvold Farm.

  Alternative vegetation includes swamp white oak, Princeton elm, cottonwood, high bush cranberry, elderberry, and hazel.

Alternative vegetation includes swamp white oak, Princeton elm, cottonwood, high bush cranberry, elderberry, and hazel.

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Claire Hinther is a rising junior at St. Olaf College in Northfield, MN. She is pursuing a double major in political science and environmental studies with a concentration in women’s and gender studies. A native of Missoula, Montana, she grew up hiking in Glacier National Park, biking in Western Montana and Idaho, and spending long days fishing and swimming the three rivers in her hometown. Through these childhood experiences, she has developed a deep love for the outdoors and a great appreciation for the value of our environment.