Every summer Midwesterners watch strong thunderstorms rumble overhead, complete with gusting winds and torrential rains. But, what happens to that 20 mph rain drop after it crashes into the ground from thousands of feet above the earth's surface?
That's the question running through Tyson Ochsner's mind as he studies the subsurface journey of water and chemicals as a soil scientist on the University's St. Paul Campus.
Understanding the interaction between water and soil is important for determining the best agricultural management practices, says Ochsner, who works for the Soil and Water Management Research Unit of the USDA Agricultural Research Service.
"How are chemicals moving in the sub-surface environment?" he poses. "It actually varies a lot, depending largely on how water is flowing through the soil."
In the belly of Borlaug Hall, Ochsner and ARS technician Todd Schumacher have built several foot-high transparent plastic tubes to get a clear view of a process usually hidden to the casual observer. Each tube is filled with a different type of sand or soil and connected to a water supply. The tubes also house small, custom-built sensors.
"We are working to develop a new method for measuring soil water flow rates," Ochsner explains.
The sensors introduce a heat pulse in the soil and monitor the transfer of that heat pulse. The heat transfer is determined, in part, by the water flow rate, Ochsner says.
"If we can develop a reliable way to predict this relationship between the heat transfer and the water flow rate, then the heat pulse method will deliver accurate soil water flow measurements. This method could then be used to monitor soil water flow at points of interest in the landscape."
"The goal of this work is to develop a tool that scientists and engineers can use to monitor water flow in the soil," he adds.
Ochsner, an adjunct assistant professor with the Department, says his interests in areas of soil water flow, heat transfer, and nitrate leaching are the result of life-time exposure to agriculture.
He grew up on a farm in Oklahoma's Tillman County, home to 9,287. Beginning at the age of 12, Ochsner worked closely with his parents and siblings and completed tasks that included driving tractor, building fences, and chopping cotton.
"We did it all," he says.
Ochsner found his niche in the classroom and school activities, as well, playing an active role in the National FFA Organization.
"Since high school, I've always had an interest in soil and water conservation," he says. "And, I've always been involved in agriculture."
That interest started Ochsner on a northward journey beginning at Oklahoma State University, where he graduated in 1998 with a degree in environmental science. Then, he started his graduate work at Iowa State University, finishing his masters and Ph.D. in soil science and water resources. During that time, he also received a grant to travel to China, where he learned and shared about many aspects of soil physics.
"I learned about their agriculture and some of their environmental problems, particularly industrial pollution, drought, and receding water tables," he says. "I also visited several agricultural research institutes and an agroforestry and tourism development project in the Taihang Mountains."
Shortly after graduation, Ochsner hopped the border and started work as a scientist in St. Paul in the summer of 2003. Now, at the ARS Soil and Water Management Research Unit, Ochsner uses his interests in physics, hydrology and soil science to study agricultural issues related to ground and surface water quality, and to soil carbon and conservation tillage.
"My role is to conduct research that makes a contribution in one of those two areas," he says. "I'm seeing what abilities and skills I have as a scientist and seeing what the research needs are."
One need is more study on contaminant transport, an area of research Ochsner says could directly help farmers trying to decide what types of tillage and fertilization practices to use.
Another project co-authored by Ochsner and published in the Soil Science Society of America Journal introduced a "new concept for measuring the partitioning of the soil volume between water, solids, and air" through the use of thermal and electromagnetic signals. Farmers can use knowledge about soil partitioning to enhance agricultural production by identifying and alleviating soil compaction. The method yielded promising results and without the radiation hazards of past techniques.
Ochsner says working in the field and working with students are rewarding parts of his new job and the Department has provided a good place to start his career.
"I've enjoyed the people I've interacted with," he says. "I appreciate their help. I'm the new guy coming in, but they've given me the resources I need."
Ochsner lives in Hastings and, when not solving subsurface mysteries, enjoys spending time with his wife Stephanie and their children Audrey and Isaac.
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