By DIANE HELDT
Staff Writer
Ames Laboratory researchers have found that X-ray technology can provide on-the-spot accurate measures of grain yields.
The Ames Lab and Iowa State University scientists have mounted X-ray technology on corn harvesters to gather data on how much grain is being produced on five-meter to 10-meter segments of land.
Joe Gray, an Ames Lab scientist who also heads the Center for Nondestructive Evaluation's X-ray group, and Feyzi Inanc, a member of the center's X-ray group, began the study last summer in an effort to find better ways to measure grain flow. The project was the idea of Selcuk Arslan, an ISU graduate student in agricultural and biosystems engineering who did his thesis on grain monitoring and methods of measuring yield.
"People use grain yield in precision farming, but if you don't have a good map of the yield from your field, you don't get as much benefit from it," Gray said. "We wanted to find a way to get more resolution and a more detailed map of the field."
Grain yield is crucial information for commercial and research farms that use the precision farming method, Gray said. But grain yield measurements have long been a weak link in the precision farming approach, he said.
The most commonly used method of measuring grain yield is a force monitor, which acts like a spring and measures the pressure of the falling grain as it hits the spring and gives the average yield for the field, Gray said. The problem with that method is that the field varies -- there are bare spots and wet spots -- so it's not a very accurate measure for precision farming, he said.
"We don't want to know the average," he said. "We want to know how much grain is being produced in each specific part of the field."
Using X-ray technology provides a high level of accuracy while eliminating many of the drawbacks associated with other yield measurement systems, Gray said.
"Ours is independent of the moisture content of the grain and other differences in the field," he said. "We're already better than the commercial monitors that are already available."
The preliminary study, funded by the U.S. Department of Energy, was done on corn, but the technology could be used on a variety of grains, soybeans, potatoes and other crops, Gray said.
The next big step in the research will be to do field demonstrations, probably this summer, Gray said. The preliminary research was done in the lab, which is much different than a field, he said.
"We're starting to look at what we can do in a much more realistic setting," he said. "In a field you have the big equipment bouncing up and down, and you don't want to have your X-ray equipment go out at the first bump."
The scientists came up with a system that allows X-ray equipment to be mounted on either a harvester or a grain elevator. As the grain passes through a low-energy X-ray beam on the way to the collection bin, information is relayed to a computer and translated into yield data.
The grain doesn't come into contact with the measuring device, preventing the buildup of dirt and dust that could interfere with the equipment's effectiveness, Gray said. The technique also has a wide dynamic range, meaning that the flow of the crop can vary widely without requiring the equipment to be recalibrated to adjust for changes, he said. Also, the X-ray equipment is insensitive to the differing moisture content of the grain, which can throw the other measuring devices off, Gray said.
The radiation from the X-ray machine is not a problem, Gray said. It is low enough that 2 to 3 millimeters of steel shielding will protect the equipment operator from exposure, and the grain's exposure to the beam lasts a fraction of a second and doesn't pose a radiation risk, he said.
"When you're working with X-rays, safety is always a concern and you want to minimize any kind of exposure you get," he said. "We were able to demonstrate that the radiation hazard is practically non-existent."
Gray has applied for a patent on the technique and has also had extensive conversations with a software company about the system, he said.
"We're happy that at this early stage we have someone interested in it," he said.
Publication date: June 9, 1998
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Last revision: 6/10/98 sd
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