New Test for Soil Salinity and Sodicity
By Kathryn Barry
December 15, 1998
With a new test kit, farmers and land managers can determine--right in the
field--whether their soils contain too much salt or sodium. The kit is based on
research at the Agricultural Research
Service, the U.S. Department of
Agriculture's chief scientific agency.
An estimated 30 percent of irrigated land in the United States and 50
percent worldwide is salt-affected.
Soil salinity increases as irrigation waters evaporate and leave salts
behind. Sodic soils have too much sodium relative to calcium and magnesium.
Both conditions hinder plant growth and reduce crop yields.
To measure salinity and sodicity, growers normally collect soil samples and
send them to a laboratory. Analysis may take up to 2 months and cost $50 per
The new test relies on electrode measurements rather than chemical analysis,
and gives results in 10 minutes for about $3 per sample. It was developed under
a Cooperative Research and Development Agreement between ARS'
U.S. Salinity Laboratory in
Riverside, Calif., and the Hach
Company in Loveland, Colo.
The kit also includes easy-to-use computer software and a manual to help
users take steps to improve their soil quality.
Land management agencies that help farmers, such as the USDAs
Natural Resources Conservation Service
and the United Nations
Food and Agriculture Organization, are
expected to be the biggest users.
Scientific contact: Scientific contact: James Rhoades, ARS U.S.
Salinity Laboratory, Riverside, Calif., phone (909) 369-4867, fax (909)