Match List I with List II and select the correct answer using the code given below the lists: List I (Soil Type) A. Entisols B. Inceptisols C. Histosols D. Oxisols List II (Salient Characteristic) 1. Soils having weakly or quickly developed horizons 2. Weakly developed soils with no horizons 3. These soils are very old and highly weathered 4. These soils have very high quantity of organic matter in the upper layers Code:
- (a)2, 1, 4, 3
- (b)2, 4, 1, 3
- (c)3, 4, 1, 2
- (d)3, 1, 4, 2
Correct — A, 2, 1, 4, 3. The four soil orders in List I are from the United States soil taxonomy, and each name carries its own definition. Entisols are recently formed soils that lack well developed horizons, so A goes to 2, weakly developed soils with no horizons. Inceptisols are young soils in which horizon formation has begun but has not gone far, with little eluviation or illuviation, so B goes to 1, soils having weakly or quickly developed horizons. Histosols are the organic soils, formerly called bog soils, with more than about a fifth of their material organic matter, so C goes to 4. Oxisols are the most weathered order of all, deep tropical soils rich in iron and aluminium oxides and poor in nutrients, so D goes to 3, very old and highly weathered. Reading the sequence off gives 2, 1, 4, 3.
- (b)2, 4, 1, 3 — Gets Entisols right and then swaps Inceptisols with Histosols. Inceptisols are defined by the beginning of horizon development, not by organic matter, and organic matter is precisely what defines Histosols.
- (c)3, 4, 1, 2 — Starts by calling Entisols old and highly weathered, which reverses the whole point of the order — Entisols are the youngest soils in the taxonomy, so young that no horizons have formed.
- (d)3, 1, 4, 2 — Again begins with Entisols as the highly weathered order, and then leaves Oxisols paired with the beginning-of-horizon description that belongs to Inceptisols.
The United States soil taxonomy sorts soils into twelve orders on observable properties, chiefly the presence and kind of diagnostic horizons. Four of them appear here. Entisols are so recent that no horizons have developed. Inceptisols show the beginnings of horizon formation. Histosols are organic rather than mineral soils, formed where waterlogging slows decay. Oxisols are the end point of tropical weathering, with most of the weatherable minerals gone and iron and aluminium oxides left behind. Inceptisols and Entisols together cover the largest share of India's area, the first largely on the northern plains and the second on recent alluvium, coasts and eroded slopes.
Every match here can be recovered from the name if the roots are known. Entisol carries recent, Inceptisol carries inception or beginning, Histosol carries the Greek histos for tissue and so organic material, and Oxisol carries oxide. Two of the four descriptions are close enough to be worth separating carefully: no horizons at all against weakly or quickly developed horizons. The first is Entisols, the second Inceptisols, and the ordering in List II is deliberately reversed against List I so that a candidate who matches by position rather than by meaning goes wrong at the first step. Once A is fixed to 2, only two options survive, and the Histosol-to-organic-matter link settles it.
- Entisols are recently formed soils that lack well developed horizons.
- Inceptisols are young soils that have begun to form subsurface horizons but show little eluviation or illuviation.
- Histosols are organic soils, formerly called bog soils, with more than about 20 per cent organic matter.
- Oxisols are the most weathered order, rich in iron and aluminium oxides, with low nutrient content and low cation exchange capacity.
- Inceptisols cover the largest geographical area among soil orders in India.
List II is printed out of order against List I, so matching by position fails at the very first pair.
- Matching lists by position instead of by meaning — List II here is deliberately shuffled.
- Confusing Entisols and Inceptisols, which differ only in whether horizon formation has started.
- Assuming Oxisols are fertile because they are deep; heavy weathering has stripped their nutrients.
As a match-the-list item on soil orders and their characteristics, or as a single-answer question on which order is organic or which covers the largest area in India.
CDS_GK_2021_II_Q662021Inceptisols, Entisols, Vertisols and Mollisols are orders of which one of the following?
- (a) Sugarcane
- (b) Soil
- (c) Coal
- (d) Copper
Answer(b) Soil
The same vocabulary at its most basic — recognising that these names are orders in the soil taxonomy at all. Two of the four appear again in the 2022 matching item.
CDS_GK_2020_II_Q112020The largest geographical area of India is covered by which one of the following types of soils?
- (a) Inceptisols
- (b) Entisols
- (c) Alfisols
- (d) Vertisols
Answer(a) Inceptisols
Puts the same two orders on the Indian map. Inceptisols, the soils in which horizon formation has just begun, cover more of India than any other order, with Entisols close behind on recent alluvium and eroded ground.
- practice — not a real PYQ
Which one of the following soil orders is an organic soil?
- (a)Aridisols
- (b)Histosols
- (c)Oxisols
- (d)Vertisols
Answer(b) Histosols — formed where waterlogging slows decay, with a very high proportion of organic matter in the upper layers.
- practice — not a real PYQ
Which soil order is characterised as the most highly weathered, dominated by oxides of iron and aluminium?
- (a)Entisols
- (b)Inceptisols
- (c)Mollisols
- (d)Oxisols
Answer(d) Oxisols — the end point of tropical weathering, nutrient-poor despite their depth.