Portable Spectrometry Device Assesses Soil Health

A portable field sensor has been used to accurately measure minerals in soils more easily and efficiently than laboratory-based methods. The technique, known as portable x-ray fluorescence spectrometry (PXRF), was used to determine the calcium (Ca) concentration of 75 soil samples from four U.S. states. PXRF can provide data on about 20 different elements in 60 seconds.

Extensive calcium carbonate accumulation engulfs this soil layer, making it difficult for plant roots to break through. Courtesy of David C. Weindorf/Texas Tech University.

According to soil scientists from Texas Tech University, the portable sensor provides an important analytical tool for the evaluation of soils containing Ca as part of calcium carbonate (CaCO₃), which can damage the soil in excessive amounts. In addition to providing an advantage for soil scientists working in the field, it could help scientists and farmers in developing countries who cannot afford expensive laboratory tests, or don’t have the expertise to visually appraise the soil.

“Essentially, PXRF is another tool in the tool belt of the modern soil scientist, but it is by no means the only tool,” said Texas tech scientist David Weindorf. His daughter, Camille, participated in the research, scanning soil samples and helping her father perform the laboratory tests. She also helped calculate the summary statistics and write the paper.

Part science fair, part hard-core science: Middle school student Camille Weindorf scans soil samples with a portable x-ray fluorescence (PXRF) spectrometer mounted in a hooded test stand. Courtesy of David C. Weindorf.

“I hope a project like this can inspire other students around her age to engage in original scientific inquiry,” Weindorf said. “Truly, they are the future [that] will keep our country at the forefront of scientific innovation.”

The research was published in Soil Science Society of America Journal (doi:10.2136/sssaj2017.01.0019).