UPSC Prelims 2011 Q78: Geography – Physical Geography & Geomorphology
Salinization occurs when the irrigation water accumulated in the soil evaporates, leaving
behind salts and minerals. What are the effects of salinization on the irrigated land?
- (a) It greatly increases the crop production
- (b) It makes some soils impermeable
- (c) It raises the water table
- (d) It fills the air spaces in the soil with water
Answer: (b) It makes some soils impermeable
Explanation
Effects of salinization on irrigated land
Salinization occurs when irrigation water evaporates and leaves behind salts and minerals in the soil.
| Option | Verdict | Reason |
|---|---|---|
| (a) Greatly increases crop production | Incorrect | Salinization is harmful to crops, not beneficial; it reduces yields by damaging soil structure and plant roots |
| (b) Makes some soils impermeable | Correct | Accumulated salts/minerals can clog soil pores, reducing drainage and making some soils impermeable to water |
| (c) Raises the water table | Incorrect | Salinization is about surface salt accumulation, not a direct cause of a rising water table |
| (d) Fills soil air spaces with water | Incorrect | This describes waterlogging, a related but distinct problem from salt accumulation |
Salinization basics:
| Point | Detail |
|---|---|
| Cause | Evaporation of irrigation water, leaving salts behind |
| Effect | Soil becomes saline and sometimes impermeable |
| Consequence | Reduced crop yields, damaged soil structure |
Answer: (b) It makes some soils impermeable.
Why each option is right or wrong
- (a) Incorrect. Salinization harms crop production; it does not increase it.
- (b) CORRECT. Salt and mineral build-up can clog soil pores, making some soils impermeable to water.
- (c) Incorrect. A rising water table is a separate hydrological issue, not the direct effect of salinization described here.
- (d) Incorrect. Filling air spaces with water describes waterlogging, a related but distinct problem.
Key point
Salinization — salt/mineral build-up left behind by evaporating irrigation water — can clog soil pores and make some soils IMPERMEABLE, harming rather than helping crop production.
Remember
Salinization: evaporating irrigation water leaves salts behind, making some soils impermeable and harming crop yields.
Common mistakes
- Assuming any irrigation-related soil change boosts crop production.
- Confusing salinization with the separate problem of waterlogging.
- Not connecting salt accumulation to reduced soil permeability.
Exam tip
Salinization = salt residue harms soil structure, making it impermeable — never a production booster.
Sources
- Food and Agriculture Organization of the United Nations — Management of Irrigation-Induced Salt-Affected Soils (2005)
- NCERT Class XI Geography — India: Physical Environment — Soils