The main difference between sodic and saline soil is that sodic soil has excessive amounts of exchangeable sodium salts, whereas saline soil has excessive amounts of soluble salts.
Soil is a porous medium that is biologically active. It is found in the topmost part of the Earth’s crust and is composed of minerals, gas, soil organic matter, water, and living organisms. Moreover, the soil has five layers: organic, topsoil, subsoil, parent material, and bedrock layers. Soil has undergone biological, physical, and chemical weathering with time. According to the differences in the chemical and physical properties of the soil, we can categorize it into different types. The nature of soil can also vary according to the composition of the soil. Sodic soil and saline soil are two types of classifications.
Key Areas Covered
1. What is Sodic Soil
– Definition, Composition, Features
2. What is Saline Soil
– Definition, Composition, Features
3. Similarities Between Sodic and Saline Soil
– Outline of Common Features
4. Difference Between Sodic and Saline Soil
– Comparison of Key Differences
Key Terms
Saline Soil, Sodic Soil
What is Sodic Soil
Sodic soil is soil that has a large number of sodium ions. When the amount of sodium content impacts the soil structure, the soil is said to be sodic. The sodic nature of soil occurs when the sodium ions leached through the soil remain bound to clay particles. In sodic soil, the bond between soil particles is weak, thus, degrading the soil quality. The pH value of sodic soil is more than 8.5. This type of soil also contains dense or hard subsoil, which is prismatic or columnar in structure.
Indicators of sodicity include shallow rooting depth, low water infiltration, surface crusting, reduced vegetation, and reduced growth of crops. Also, there are several adverse effects of sodicity. Dispersion of subsoil that causes accelerated erosion is one such adverse effect, which leads to the formation of gullies and tunnels. The dispersion in the soil surface is another adverse effect of sodic soil; this inhibits water infiltration. Moreover, the reduced level of water flowing through the soil leads to minimized leaching. Minimized leaching over a longer period of time causes the accumulation of salt and saline subsoil.
What is Saline Soil
Saline soil is soil with extensive levels of salt in it. Stalinization is the process of increasing the salt content in the soil. This occurs due to the long-term continuous discharge of groundwater. The excess water from well-drained discharge zones moves to poorly drained discharge zones and gets accumulated in them. Furthermore, the salts accumulated are of different types. Examples of such salts present in saline soil include compounds of sodium, potassium, magnesium, sulphates, chlorides, calcium, and bicarbonates.
Stalinization increases the saline nature of the soil. This excessive water brings the dissolved salt into the root zone of the discharged area. Moreover, the high concentrations of these salts reduce the amount of available water, making it difficult for crops to grow in the soil. The salinity of soil also varies according to the moisture content in them. The overall salinity depends on factors such as salt content, movement, and the level or depth of groundwater.
Similarities Between Sodic and Saline Soil
- Sodic and saline soils can both have adverse effects on plant growth and crop productivity.
- Soil reclamation, which involves adding soil amendments like gypsum or organic matter to improve soil structure and fertility, can improve sodic and saline soil.
Difference Between Sodic and Saline Soil
Definition
Sodic soil is soil with excessive amounts of exchangeable sodium salts, whereas saline soil is soil with excessive amounts of soluble salts.
Composition
Sodic soil contains more sodium ions than other cations, while saline soil mainly contains compounds of magnesium, calcium, sulphates, chlorides, potassium, etc.
Process
Sodic soil is formed when sodium ions leached through the soil remain bound to clay particles, but saline soil is formed when salts accumulate in the soil in high concentrations.
Conclusion
Soil is a layer of a mixture of living and non-living components covering most parts of the land. Due to the changes in the structure of the soil, there are different soil types. Sodic soil and saline soil are two types of classifications. The main difference between sodic and saline soil is that sodic soil has excessive amounts of exchangeable sodium salts, whereas saline soil has excessive amounts of soluble salts.
Reference:
1. Hoiberg, Andrew. “Sodic Soil in a Nutshell.” Calcium Products.
2. “Soil Salinity.” Soil Management Guide – Manitoba.
Image Courtesy:
1. “Progardes Desmanthus on a sodic clay soil, Hughenden, Queensland” By Btcpg – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “Salinity in soil is a major deterrent to agriculture especially after Aila” By India Water Portal (CC BY-NC-SA 2.0) via Flickr
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