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RAS question

With reference to organic carbon (OC) content in Rajasthan's soils, which of the following is CORRECT?

Correct answer: (B) Eastern Rajasthan soils (Hadoti, Mewar) generally have higher OC than arid western soils owing to better rainfall, denser vegetation, and higher biological activity..

Eastern Rajasthan soils, including Hadoti and Mewar, generally have higher organic carbon than arid western Rajasthan soils because higher rainfall, denser vegetation and stronger biological activity add more organic matter to the soil.

  1. (A)

    Western Rajasthan soils generally have higher OC than eastern Rajasthan soils because of greater biomass from desert shrubs.

  2. (B)

    Eastern Rajasthan soils (Hadoti, Mewar) generally have higher OC than arid western soils owing to better rainfall, denser vegetation, and higher biological activity.

  3. (C)

    OC content is uniformly distributed across all soil types in Rajasthan.

  4. (D)

    Soil Health Card data shows that OC deficiency is a problem only in the Thar Desert and not in eastern districts.

Explanation

Rajasthan's soil organic carbon pattern is not uniform: it broadly improves from the hot, arid west towards the relatively wetter east. Western Thar and Marusthali soils have very low OC, often below 0.5%, because sparse vegetation gives little organic input, while high temperature and low rainfall limit accumulation. Arid western Rajasthan has low biomass and extreme temperature conditions, while less arid soil settings have higher soil organic carbon because of higher rainfall, larger vegetative input and related soil factors. That is why Hadoti, Mewar and other eastern zones, with better rainfall, denser vegetation and greater microbial activity, generally show comparatively higher OC than the arid western districts.

Why the other options are wrong

  • (A) Western Rajasthan does not normally have higher OC; its hot arid soils have sparse vegetation, low rainfall and high temperatures, so organic matter input and accumulation remain low.
  • (C) OC is not evenly distributed across Rajasthan because rainfall, vegetation and biological activity vary sharply between the arid west and the wetter eastern regions.
  • (D) OC deficiency is not confined to the Thar Desert; Soil Health Card surveys show a wider Rajasthan problem, including eastern districts affected by intensive cropping, weak manuring and residue burning.

Concept

This tests soil fertility and the climatic control of organic carbon in Rajasthan's soils. It recurs in RAS because questions often link Rajasthan's aridity gradient with vegetation, land use and nutrient status.

Source

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