Salinity and Sodicity
What it is: Salinity is an excess of soluble salts in the soil. Sodium, calcium, and magnesium most commonly form salts with chloride, sulfate, and bicarbonate. Sodicity is an excess of sodium; in sodic soils, sodium represents more than about 10% of all the cations.
Why it is important: Salinity and sodicity are important indicators because high salinity inhibits crop growth, while high sodicity leads to loss of soil structure.
Specific problems that might be caused by (too little, too much etc.) are:
High salinity: poor crop growth in non-tolerant plants; sodium, chloride toxicity
High sodicity: crusting, impermeability, sodium toxicity, micronutrient deficiencies
What you can do: You can improve your soil's salinity and sodicity levels by applying cation amendments such as gypsum to displace sodium, leaching salts well below the root zone with irrigation management or off-site through artificial drainage.
For more information go to Soil Management Practices.
Ways that you can measure salinity and sodicity include:
| Method | How Performed | Comments |
|---|---|---|
| Sodium adsorption ratio (SAR) | ||
| Exchangeable sodium percentage (ESP) | ||
| Electrical conductivity (EC) | ||
| Sodium (Na) |
The different methods have different levels of accuracy and precision.