Percent Sodium

\[\%Na=100\frac{Na^++K^+}{Ca^{2+}+Mg^{2+}+Na^++K^+}\]

Variables

PctNapercent sodium (%)

Nasodium concentration (meq/L)

Kpotassium concentration (meq/L)

Cacalcium concentration (meq/L)

Mgmagnesium concentration (meq/L)

Description

What is this formula?

Percent Sodium (%Na) quantifies the proportion of sodium and potassium relative to the total major cations present in water.

When to use it

Use it when evaluating irrigation water quality and the potential effects of sodium accumulation on soil structure and permeability.

Example

Data:

Na = 8 meq/L

K = 1 meq/L

Ca = 4 meq/L

Mg = 2 meq/L

Formula:

%Na = 100(Na + K)/(Ca + Mg + Na + K)

Substitution:

%Na = 100(8 + 1)/(4 + 2 + 8 + 1)

Result:

%Na = 60%

Applications

Irrigation water assessment, agricultural engineering, groundwater studies, soil management, environmental monitoring, and water reuse projects.

Note

Percent Sodium is an empirical indicator commonly used together with SAR, RSC, EC, and TDS. High sodium percentages may negatively affect soil permeability and crop productivity. Different classification systems use different threshold ranges.