Salinity: Electrical conductivity and total dissolved solids

Abstract

The measurement of soil salinity is a quantifi cation of the total salts present in the liquid portion of the soil. Soil salinity is important in agriculture because salinity reduces crop yields by reducing the osmotic potential, making it more diffi cult for the plant to extract water, by causing specifi c-ion toxicity, by upsetting the nutritional balance of plants, and by aff ecting the tilth and permeability of a soil. A discussion of the principles, methods, and equipment for measuring soil salinity is presented. The discussion provides a basic knowledge of the background, principles, equipment, and current accepted procedures and methodology for measuring soil salinity in the laboratory using electrical conductivity of aqueous extracts from soil samples and measurement of total dissolved solids in the saturated soil extract. Attention is also given to the use of suction cup extractors, porous matrix or salinity sensors, electrical resistivity, and electromagnetic induction to measure salinity in soil lysimeter columns and small fi eld plots (<10 by 10 m). Land resource managers, producers, extension specialists, Natural Resource Conservation Service fi eld staff , undergraduate and graduate students, and university, federal, and state researchers are the benefi ciaries of the information provided.