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United States Department of Agriculture

Agricultural Research Service


New Test for Soil Salinity and Sodicity

By Kathryn Barry Stelljes
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 sample.

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 USDA’s Natural Resources Conservation Service and the United Nation’s 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) 342-4962,

Last Modified: 5/15/2017
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