Soil technicians doing an in-field measurement for soil salinity. Photo by Tim McCabe, USDA Natural Resources Conservation Service. When doing soil salinity measurements, some things to keep in mind are: Sampling scheme and methodology Choice of in-field or laboratory measurement When reporting results, be sure to include the soil:water ratio used Calculations There are no calculations required as the results are directly read from the electrical conductivity meter. The SI units are decisiemens per meter (dS/m). The following units are equivalent: 1 (Ω.m)-1 = 1 S/m = 10 dS/m = 1 mho/m = 10 mmho/cm If the EC of a saturated paste extract is greater than 4 dS/m the soil is considered saline and could interfere with plant growth. Some salt sensitive plants may be adversely affected by salt content of 2 dS/m.