Question

Study the following statements (I - IV) related to soil salinity due to waterlogging and arrange them in the correct sequence.

I. Draw salt to the surface of the soil.
II. Waterlogging in the soil.
III. The salt is deposited as a thin crust on the land surface or on the roots of the plants.
IV. Irrigation without proper drainage of water.

• A. I → II → III → IV
• B. I → III → IV → II
• C. III → I → IV → II
• D. IV → II → I → III

Answer 1

The correct option is D IV → II → I → III

Salinity is the accumulation of salt in land or water. Soil salinity refers to the amount of dissolved salts in the soil solution (the aqueous phase in the soil). Salts such as Na⁺, Ca²⁺, and Mg²⁺ are normally present in soil.

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

Soil salinization happens due to the following reasons :

• Dry climates lead to low low rainfall and excessive salts are not flushed from the Earth.
• 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.

Irrigation or adding water to land without proper drainage can lead to problems of waterlogging in the soil. Accumulation of water draws salts to the surface of soil and their accumulation on roots of plants. The increased concentration of salts on the roots affects growth of plants and their productivity. This damages agriculture.

The waterlogging can lead soil salinization as follows:

Irrigation without proper drainage of water
$\downarrow$
Waterlogging in the soil
$\downarrow$
Draws salt to the surface of the soil
$\downarrow$
The salt is deposited as a thin crust on the land surface or on the roots of the plants

Hence option d is correct.