Question

Read the following statements (1 - 4) and identify which of the following methods can be used to address the issue of salinity in soils?

1. Decreasing fertilizer use.
2. Irrigation with proper drainage of water.
3. Overgrazing.
4. Bringing down excessive irrigation.

• A. 1, 2 and 4 only
• B. 3 and 4 only
• C. 1 and 2 only
• D. 1, 2, 3 and 4

Answer 1

The correct option is A 1, 2 and 4 only

Salinity is the accumulation of salt in land and water up to a level that causes damage to its natural environment.

Soil salinity is the presence of salt content in the soil. The process of increasing the salt content in soil is known as salinization. Salts such as Na⁺, Ca²⁺, and Mg²⁺ present in soil

Soil salinization occurs when soluble salts are retained in the Earth either naturally or because of improper anthropogenic activities, particularly farming practices.

Soil salinization happens due to the following reasons :

• Dry climates and low low rainfall leads to accumulation of salts as the excessive salts are not flushed from the soil.
• High evaporation rate adds salts to the ground surface.
• Poor drainage or water logging leads to accumulation of salts.
• Irrigation with salt-rich water amplifies salt content in soil

Decrease in fertilizer use in agriculture will help reduce the soil salinity as it prevents the salt stress due to excessive fertilizer use. Hence statement 1 is correct.

Waterlogging leads to soil salinity as it prevents leaching of the salts imported by the irrigation water. Farmers are typically advised to add gypsum to overcome soil salinity. Gypsum improves the ability of soil to drain and not become waterlogged due to a combination of high sodium, swelling clay and excess water. Application of gypsum to soil allows water to move into the soil and allow the crop to grow well. Gypsum application also improves soil aeration. Hence statement 2 is correct.

Salinity from irrigation can occur as time passes, since almost all water (even natural rainfall) contains some dissolved salts. When the plants use the water, the salts are left behind in the soil and eventually begin to accumulate. Hence proper irrigation can prevent soil salinity. So statement 4 is correct.

Overgrazing is the continuous grazing of plants by herbivores. This leads to loss of vegetation cover above the soil making it vulnerable to soil erosion as well as leaching. Hence it increases soil salinity and doesn’t address it. So statement 3 is incorrect.

Figure : Soil salinaization