UPSC Prelims 2011 · GS Paper I

Question 78: Geography

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 ?

aIt greatly increases the crop production

bIt makes some soils impermeable

cIt raises the water table

dIt fills the air spaces in the soil with water

AnswerThe answer is (b).

When irrigation water evaporates it leaves its dissolved salts behind. Over time salts build up in the root zone, and sodium salts can disperse soil particles so that the soil seals up and water cannot drain through it. Such soils become impermeable, crop yields fall, and waterlogging may follow. Salinization lowers production instead of raising it, and a rising water table is a related problem, not the direct effect of salts.

Why each option is right or wrong

(a) Salinization reduces crop production.
(b) Right: salts can make some soils impermeable.
(c) A rising water table comes with waterlogging, a related problem, not salt build-up itself.
(d) Filling pore spaces with water is waterlogging, a different problem.

Explanation: written by UPSC Grade, not by UPSC.

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Source: UPSC, Civil Services (Preliminary) Examination 2011, General Studies Paper I, Series A. The paper on upsc.gov.in.