Appendices - Soil Essentials: Managing Your Farm's Primary Asset - page 147

Appendix 3. Electrical conductivity (in dS/m)

Soil salinity refers to the free salts in the soil solution. Soils with EC values less
than 0.16 dS/m (approximately 0.05% TSS) are generally regarded as sufficiently
low to have harmless salinity. However, soil texture and other factors inf luence the
salt tolerance of plants.
Published data on the salt tolerance of agricultural crops refer to the electrical
conductivity of the saturation extract (ECe). However, obtaining the saturation
extract ECe in the laboratory is time consuming and hence not practical for the
rapid estimation of the salinity of large numbers of samples. For this reason the EC
of a 1:5 soil/water suspension is used and may be converted to an approximate ECe
value by multiplying by appropriate factors for different soil textures as shown
below:

Soil texture Multiplication factor

Sands, loamy sands 13

Sandy loams, fine sandy loams 11

Loams, very fine sandy loams, silty loams, sandy clay loams 10

Clay loams, silty clay loams, very fine sandy clay loams,
fine sandy clay loams, sandy clays, silty clays, light clays

9

Light medium clays 8

Medium clays 7

Heavy clays 6