UPSC Prelims 2012 · GS Paper I
Question 98: Environment and Ecology
Consider the following agricultural practices :
- 1.Contour bunding
- 2.Relay cropping
- 3.Zero tillage
In the context of global climate change, which of the above helps/help in carbon sequestration/storage in the soil?
AnswerUPSC’s answer is (b).
Zero tillage leaves the soil undisturbed and keeps crop residue on the surface, so soil organic carbon is not exposed to air and oxidised to carbon dioxide; carbon builds up in the soil. UPSC counts only zero tillage as storing carbon in the soil, treating contour bunding as a soil and water conservation measure and relay cropping as a way to raise cropping intensity.
- 1. Contour bunding conserves soil and water but is not counted as carbon storage.
- 2. Relay cropping raises cropping intensity but is not counted as carbon storage.
- 3. Zero tillage avoids disturbing the soil, so carbon stays stored.
Why each option is right or wrong
- (a) Wrong: contour bunding and relay cropping are not counted as carbon-storing practices.
- (b) Correct: zero tillage helps store carbon in the soil.
- (c) Wrong: contour bunding and relay cropping are not counted.
- (d) Wrong: zero tillage does help sequester carbon.
Worth knowing: Contour bunding and relay cropping can also help retain soil carbon by reducing erosion and keeping cover, so the key is debatable; UPSC's answer is zero tillage only.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2012, General Studies Paper I, Series A. The paper on upsc.gov.in.