Agricultural News
OSU Researchers Using Cosmic Rays to Measure Soil Moisture
Fri, 20 Nov 2015 11:29:29 CST
Researchers at Oklahoma State University are working with cutting-edge technology that provides high-quality soil moisture data that may prove useful to help predict floods and wildfires.
"It's a revolutionary kind of technology that has not existed until just a few years ago," said Tyson Ochsner, Sarkeys professor in OSU's Department of Plant and Soil Sciences.
Oschner has labeled this new instrument a Cosmic Ray Neutron Rover. The Rover uses cosmic ray technology first developed by Marek Zreda, hydrology and water resources professor at the University of Arizona, who created a network of stationary probes around the country called the COsmic-ray Soil Moisture Observing System.
"The Rover uses cosmic rays as a way of inferring soil moisture over a large area by counting neutrons above the ground," Ochsner said. "High energy cosmic rays are constantly coming in at the top of our atmosphere. These are mostly high-speed protons, and they collide with atoms and molecules in our atmosphere and eject neutrons, which travel at a very high rate of speed. Those continue down through the atmosphere and then start to interact with molecules near the land surface."
Most notably, these fast neutrons begin to interact with hydrogen molecules.
"Hydrogen has an atomic mass unit of one and the neutron has an atomic mass unit of one," he said. "When they hit each other, the neutron loses a lot of its speed because it's the same weight, so hydrogen is really effective at slowing those neutrons down. The fewer fast neutrons, the more hydrogen we have near the surface of the earth, mainly in the form of soil moisture."
Funded by National Science Foundation's Experimental Program for Stimulating Competitive Research program, the Rover currently being tested at OSU is a larger version of the COSMOS instrument that can detect more neutrons in a short amount of time, according to Ochsner.
"Because the Rover is portable, we can put this large neutron counter in a vehicle, drive down the gravel roads, and sense the soil moisture in fields around us, so we can start to make detailed soil moisture maps," said Ochsner. "There are probably only five or six of these rovers in use today. There aren't many of these built with this purpose in mind."
Ochsner said the goal of this research is to learn what major factors control soil moisture variability from one location to another.
"We can feed this detailed soil moisture information into a decision support or modeling framework," he said. "Within this framework, we can make more accurate predictions about potential floods and wildfires."
This research also could potentially benefit ranchers who can adapt their stocking rate so they do not overgraze.
"That's an application that we hope to develop," Ochsner said.
Currently, the OSU research team is focused on documenting the calibration and validation procedures for the Rover that will help establish precise instructions for its use, which they could then teach to other researchers across the state to expand these detailed soil moisture maps.
"The Rover will be infrastructure to be shared among other researchers in Oklahoma," Ochsner said. "By the end of the project, we hope this is a resource that is developed for other people to use."
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