A High-Tech Look at Soil Composition

The prototype of an instrument designed to provide in-field analysis of key soil constituents is being tested this month by the Agricultural Research Service (ARS) and Veris Technologies of Salina, Kan.

The instrument, a thick soil shank with sensors that take readings through a sapphire "window" on its bottom, uses near infrared reflectance spectroscopy (NIRS) technology previously developed by ARS.

The prototype was built and tested for mechanical durability by Veris, a designer and manufacturer of soil sensors and of controls that adjust planting and fertilizing rates on equipment. The firm and ARS will conduct the trials in fields in Kansas and Iowa as outlined in a cooperative research and development agreement.

Veris is a division of Geoprobe Systems, a worldwide supplier of environmental and geotechnical equipment, also based in Salina.

NIRS has shown good laboratory results for measuring carbon, nitrogen and other soil constituents, says David A. Laird, who led the research on the technology at the Soil and Water Quality Research Unit of ARS' National Soil Tilth Laboratory in Ames, Iowa. ARS is the U.S. Department of Agriculture's chief scientific research agency.

If this method could be applied without substantial loss of measurement accuracy, a rapid field analysis of soil would be possible, according to Laird, a soil scientist. Previous attempts have used designs that were subject to interference from dust and mud.

Recent environmental developments have created increased demand for in-field measurement of important soil constituents, such as carbon and nitrogen. Soil carbon measurements help determine how much carbon is being stored in the soil, and soil nitrogen measurements could be used to minimize the amounts of nitrates leaching into groundwater and waterways.