Look at Soil Composition
By Luis Pons
October 9, 2002
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
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.