For decades, NASA (National Aeronautics and Space Administration) satellites have helped researchers monitor Earth’s surface, capturing images and data to track and anticipate weather patterns, determine availability of moisture in soil, and predicting severity and impacts of flooding. But for much of that time, one critical piece of information was overlooked: moisture in vegetation that grows from the soil. Once considered noise—an inconvenient byproduct in satellite readings—adding this data back to the discussion may become invaluable for understanding agriculture on a more comprehensive level.
Brian Hornbuckle, professor of agronomy, is harnessing this data to explore how moisture levels in plant tissue respond to changing weather conditions.
“The focus of my career has been thinking about: how can we use these new satellite resources to help us here in the Corn Belt do things better than we have in the past?” Brian explains.
He and a former graduate student, who now works at the U.S. Department of Agriculture (USDA), hypothesized that satellite data would show plants losing less water throughout a day when under drought conditions.
“And that’s exactly what we saw at three different locations in Iowa, so we’re really excited about that,” he says. “But there’s more work to be done. By measuring moisture levels across large areas with satellites, we can predict where crops might be struggling long before we see visible signs of drought damage. That means farmers can make better decisions about marketing, conservation, and planting strategies, and we can build better models to anticipate future climate challenges.”
When plants don’t have enough soil moisture, they become stressed, and that stress can have cascading effects—reducing growth, lowering yields, and making crops more vulnerable to pests and disease. Brian hopes to include more data sites across the state as well as observe what role weather conditions besides drought—humidity, for example—might play in plant water stress.
By refining satellite-based plant moisture measurements, Brian’s research could help improve models that predict drought stress and its impact on yield, and guide farming practices.
“In Iowa, we’ve grown corn and soybeans for decades, and that’s worked out for a couple of reasons. We have fantastic soils as well as shallow groundwater here and corn and soybeans can tap into that over the course of a summer with their roots. It turns out these crops use a more water in the summer than we get in rainfall. It’s this rainfall that we get the rest of the year that gets stored underground that usually gets us through the growing season.”
Brian hopes his ground and plant moisture data from satellites would help if Iowa came to a point where farmers can’t rely on groundwater to make up the difference.
“We could start thinking about how can we keep track of how much water is in our soil before the growing season. Because there may be some years in the future where we may say, ‘all right, we’re not going to have enough water to grow corn and soybeans this year. We should plant something else.’”
But for all the impact his research may have, what he’s most proud of is his work with students. “I do research to teach,” Brian says. His large weather and climate course reaches hundreds of students each year, many of whom will go on to careers outside of science. “Future lawyers, business leaders, and policymakers will be making decisions that affect our climate,” he explains. “This is my chance to give them the scientific foundation they need.”
He also mentors first-year agronomy students, helping them develop the mindset of a scientist—forming hypotheses, analyzing data, and applying their findings to real-world agricultural challenges. He emphasizes that agronomy is now being seen as more than just an art based on passed down knowledge of the land. There is a great need to make more quantitative predictions, and he is happy that his department is rising to that challenge. Through his research and teaching, he’s not just uncovering new scientific insights—he’s equipping students with the skills and knowledge to tackle the challenges of the future.
By Susan McNicholl, Iowa State University Office of the Vice President for Research