What is soil salinity?

Soil salinity describes the concentration of soluble salts in the soil. It is commonly expressed as the electrical conductivity (EC) of a soil extract, usually in deciSiemens per meter (dS/m). High salinity can reduce plant water uptake, cause ion toxicity and ultimately lower crop yields.

Which EC units are most common for soil salinity?

Soil salinity is typically reported as EC in dS/m for saturation paste extracts, or in µS/cm or mS/cm for soil water or irrigation water. The units dS/m, mS/cm and mmhos/cm are numerically equivalent. 1 dS/m = 1 mS/cm = 1 mmho/cm = 1000 µS/cm = 0.1 S/m.

How do you classify soil salinity from EC?

One commonly used classification, based on the EC of the saturation paste extract (ECe), defines soils as non-saline when ECe is below 2 dS/m, slightly saline at 2–4 dS/m, moderately saline at 4–8 dS/m, strongly saline at 8–16 dS/m, and very strongly saline above 16 dS/m. The calculator shows this class using your EC value converted to dS/m.

Can I convert EC to ppm (mg/L) of salts?

Yes, but only approximately. A common empirical rule for water is ppm ≈ EC (dS/m) × 640, although other factors such as 500 or 800 are also used depending on the ionic composition. The converter lets you choose the factor and displays the estimated ppm with a clear warning that it is an approximation.

Is this soil salinity calculator a substitute for laboratory analysis?

No. The calculator helps interpret and convert EC values but does not replace proper soil sampling, laboratory analysis or agronomic advice. For management decisions such as leaching requirements, crop selection and fertilizer strategies, always consult local guidelines and qualified professionals.

Soil Salinity EC Converter

Agronomy & irrigation support

Convert soil electrical conductivity (EC) between dS/m, mS/cm, µS/cm, S/m and mmhos/cm. Estimate salt concentration in ppm and classify soil salinity from non-saline to very strongly saline using widely adopted thresholds.

Note: EC to ppm conversions are approximate and depend on water chemistry. Use this tool as a guide alongside local agronomic recommendations and laboratory reports.

EC unit converter – dS/m, mS/cm, µS/cm, S/m, mmhos/cm

Single input, all units updated

EC value

Enter the measured electrical conductivity value from your meter or lab report.

Input unit

dS/m

Standard for soil salinity (ECe).

mS/cm

µS/cm

S/m

mmhos/cm

Typical presets:

Estimated salts in ppm & salinity class

Based on EC converted to dS/m

The following values are derived from the EC value converted to dS/m. The ppm estimate uses an empirical factor and should be treated as a rough guide, not a lab-equivalent measurement.

EC → ppm factor

Approximation: ppm ≈ EC (dS/m) × factor.

Estimated salts (ppm or mg/L)

Applies mostly to soil solution / water, not directly to bulk soil.

Salinity class (USDA-style)

Based on ECe in dS/m: <2 non-saline, 2–4 slightly, 4–8 moderately, 8–16 strongly, >16 very strongly saline.

Interpretation

Soil salinity classes and EC ranges

The following table summarizes typical salinity classes based on the electrical conductivity of the saturation paste extract (ECe) in dS/m and approximate equivalent µS/cm.

Class	ECe (dS/m)	Approx. µS/cm	Typical impact on crops
Non-saline	< 2	< 2000	No yield reduction for most crops due to salinity.
Slightly saline	2 – 4	2000 – 4000	Sensitive crops may begin to show yield decline.
Moderately saline	4 – 8	4000 – 8000	Many crops experience moderate to strong yield losses.
Strongly saline	8 – 16	8000 – 16000	Only salt-tolerant crops perform reasonably well.
Very strongly saline	> 16	> 16000	Few crops tolerate these conditions without remediation.

Understanding soil salinity and EC units

Soil salinity is usually quantified through electrical conductivity (EC) of a soil solution or a saturation paste extract. Ions dissolved in water (such as Na⁺, Ca²⁺, Mg²⁺, Cl⁻, SO₄²⁻) carry electrical current; the higher the ion concentration, the higher the EC.

The SI unit for EC is Siemens per meter (S/m), but in agronomy more practical submultiples are used:

dS/m – deciSiemens per meter (0.1 S/m), common for soil saturation extracts.
mS/cm – milliSiemens per centimeter, numerically equal to dS/m.
mmhos/cm – older notation, also numerically equal to dS/m.
µS/cm – microSiemens per centimeter; 1 dS/m = 1000 µS/cm.

Key equivalences used in this calculator

1 dS/m = 1 mS/cm = 1 mmho/cm

1 dS/m = 1000 µS/cm

1 dS/m = 0.1 S/m

General conversion relationships

\(\text{dS/m} = \dfrac{\mu\text{S/cm}}{1000}\)

\(\mu\text{S/cm} = \text{dS/m} \times 1000\)

\(\text{S/m} = \text{dS/m} \times 0.1\)

Approximate conversion from EC to ppm (mg/L)

EC measures conductivity, not mass directly. However, for typical irrigation waters an empirical relationship is often used:

\(\text{ppm (mg/L)} \approx \text{EC (dS/m)} \times \text{factor}\)

The factor depends on the ionic composition and temperature of the solution. Values between 500 and 800 are commonly used; the calculator lets you choose 500, 640, 700 or 800 to match your local guidelines.

Worked example: classifying soil salinity

Lab report gives ECe = 6.5 dS/m.
Enter 6.5 as EC value and select dS/m.
The converter identifies the soil as moderately saline (4–8 dS/m).
If you choose factor 640, the estimated salts are roughly 6.5 × 640 ≈ 4160 ppm.

FAQ: soil salinity and EC interpretation

What is the difference between EC of saturation paste and soil water?

The EC of the saturation paste extract (ECe) is measured on a standardized mixture of soil and water at saturation, and is the basis of many classification systems. EC measured directly in soil water or irrigation water may differ significantly and needs careful interpretation or conversion tables to relate it to ECe.

Can I compare EC values from different labs?

Only if the extraction method, soil-to-water ratio, temperature correction and units are clearly documented. Always check the method section of the report. When in doubt, consult the lab or local agronomy services before making management decisions.

How can high soil salinity be managed?

Typical strategies include improving drainage, applying sufficient high-quality irrigation water to leach salts below the root zone, selecting salt-tolerant crops or rootstocks, and managing fertilizers and manures to avoid additional salt loading. All of these require local expertise and often several seasons to show full effect.