Technique Models Movement of Water and Chemicals in Soil

Sept. 25, 2001
Scientists at the USDA's Agricultural Research Service (ARS) have developed a quick and easy method for measuring water and chemical movement in soil. The researchers say the measuring technique will increase the accuracy of mathematical models that estimate potential groundwater contamination by agrochemicals.

The method used for this measurement has not been widely used outside of laboratory conditions because of the difficulty in meeting all of the necessary model parameters that come up when modeling transport through natural soils say the researchers. However, ARS soil scientist Dan B. Jaynes at the National Soil Tilth Research Laboratory in Ames, Iowa, working with researchers at Iowa State University-Ames and Japan's Iwate University, have developed and validated the new method.

They use time domain reflectometry (TDR) to characterize solute transport in undisturbed, structured soils with distinctive flow properties. The scientists liken TDR to radar, because it measures the time and distance of reflected electrical signals in metal rods that are inserted into 8-inch-long by 5-inch-diameter columns of undisturbed, structured soil. The research team says the TDR method is simple and minimally disruptive and provides estimates of field soil properties that enable scientists to predict how water and chemicals will move through the soil.

The ARS said the new method would allow for the return of model parameter estimates as reliable as the more traditional but time-consuming measurement methods.

Source: EarthVision Environmental News

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