Matthew Maciosek Gets His Hands Dirty to Keep Groundwater Clean

Growing up in Minnesota, Matthew Maciosek spent much of his time outdoors exploring wetlands and marshes — water-rich ecosystems that support insects, wildlife and entire ecological communities. The water in those communities, however, is at risk due to agricultural practices that draw groundwater and surface water.

Now Maciosek is a fourth-year biological systems and engineering major at the University of California, Davis, where his research focuses on water use in farming. By improving irrigation practices and understanding how water moves through agricultural systems, Maciosek believes it’s possible to reduce those impacts and help preserve wetlands for future generations.

“I grew up being outside. I thought that if I went into agriculture, I can help with better irrigation practices, save this water, and the marshes will be able to come back. People will be able to enjoy these spaces in the future," he said.

That early connection to the outdoors now drives Maciosek’s research in the Kisekka Lab, led by Professor of Biological and Agricultural Engineering Isaya Kisekka, where he studies groundwater management, irrigation systems and nitrate contamination in California’s Central Valley.

Fieldwork in the Central Valley

As an undergraduate researcher, Maciosek’s expectations of engineering research have evolved.

“When I first got here, I imagined all these fancy machines and advanced technology,” he said. “But when I joined the lab, we go to the field with handheld tools. It’s a lot of getting your hands dirty.”

Literally — Maciosek goes into agricultural fields throughout the Central Valley to maintain and collect samples from vadose zone monitoring systems, instrumentation that goes beneath crop root zones that allows the researchers to track how water and dissolved nitrates move through soil over time. Nitrate transport through soil and into groundwater aquifers is a pressing issue across California agriculture.

“In California, especially the further south you go, nitrate levels are above the Environmental Protection Agency’s minimum requirement,” he said. “We want to look at conservation practices that can help mitigate this nitrate contamination.”

Using vadose zone monitoring systems with tubing placed diagonally beneath the root zone, the researchers collect subsurface water samples at multiple depths. By applying a vacuum, they extract water from the soil profile and analyze the samples for nitrate concentrations, tracking how contaminants move through the soil, particularly after major weather events.

“It’s been interesting to see what happens with all these atmospheric rivers,” Maciosek said. “When we get those rains, there’s a lot more nitrate transport in the soil. You’ll see nitrate percolate to lower soil horizons in the vadose zone.”

The lab also monitors soil water levels and soil moisture using neutron probes, which emit neutrons into the soil and measure their return to determine moisture content. These measurements allow researchers to compare fluctuations in soil water levels with patterns of nitrate transport, helping them better understand how water movement influences contaminant migration.

Irrigation practices play an important role in this process. Because soil chemistry and nitrate movement are closely tied to how water is applied to fields, Maciosek’s research also examines how different irrigation systems influence groundwater and soil health.

In orchard systems, for instance, micro-irrigation and subsurface drip systems deliver smaller, targeted amounts of water. In contrast, alfalfa fields often rely on flood irrigation.

“Those different irrigation practices may impact the quality of the soil, the nitrate in the soil and how fast nitrate percolates into the ground and into aquifers,” he said.

Understanding those differences is essential for developing conservation practices that reduce environmental impact while remaining economically viable for growers.

“We want to show that conservation practices work,” Maciosek said. “If they reduce costs on the farm or even improve yield while reducing usage, we want to show farmers that it benefits them.”

From California to Bhutan

Alongside his biological systems engineering degree, Maciosek is pursuing a minor in geographic information systems, or GIS. GIS is a computer-based tool used for analyzing and visualizing spatial data. By mapping and layering datasets like elevation, precipitation, land use and crop yields, researchers can identify patterns across landscapes that would be difficult to detect through traditional analysis alone.

GIS, says Maciosek, makes the data accessible for engineers, as well as to growers and policymakers.

“It can be displayed in ways that people with very little knowledge on these topics can understand,” he said. “I hope GIS can expand awareness to issues like nitrate contamination and bring more people in to help tackle the problem.”

Maciosek’s GIS skills were applied internationally in 2024 during a study abroad program in Bhutan, a country known for measuring progress through Gross National Happiness and for its strong environmental protections.

The country wants to expand agriculture to reduce dependence on imports, but, Maciosek explained, robust conservation laws protect its forests, meaning fields can’t just go anywhere.

Working with precipitation, elevation and yield data, Maciosek helped identify optimal areas for agricultural expansion. He also saw firsthand what can happen when researchers work directly with farmers to determine not only what is truly needed but also what is actually viable. For instance, if a solution costs too much for the farmers, it won’t be implemented.

“If we work closer with farmers, ask them what they need, what impacts they want to see on their farm, I think that will be beneficial for growers and the farming community as a whole.”

Looking Homeward

While Maciosek's current research is specific to California's soil and climate, he hopes its impact will extend beyond state borders. He eventually wants to return to Minnesota, where agricultural practices face different challenges — high water tables instead of California's aridity — but where nitrate contamination persists.

For Maciosek, the greatest reward isn't just the data or the publications — it's knowing his work contributes to something larger.

"I'm able to be a part of the solution to these problems, to be a champion for the future of agriculture," he said. "Hopefully, we can make it so that we're fully sustainable one day, that we don't have to rely on draining groundwater supplies or contaminating it."

Better irrigation isn't just about efficiency or yield. For Maciosek, it's about ensuring that future generations can walk through marshes the way he did. His hands may get dirty in California's fields, but his eyes remain on the water that feeds the wild spaces he hopes to help restore.