Environmental Studies · Geography

Soil Science

1,537 Questions

Soil Science examines the formation, classification, and properties of soil as a critical natural resource. This hub offers practice questions covering soil horizons, soil types like laterite and black soil, and regional soil characteristics. The content is highly useful for agriculture exams and civil services preparation.

Soil typesSoil horizonsSoil formation factorsAgricultural soil requirementsIndian soilsForest and mountain soils

Soil Science Questions

Multiple choice evs mud and stones soil - formation and profile soil-nature soil profile

Humus is an example of

  1. Crystalloids

  2. Organic colloids

  3. Soil structure

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

There are four major types of colloids present in soil :

1. Layer silicate clays 
2. Iron and aluminum oxide clays (sesquioxide clays) 
3. Allophane and associated amorphous clays 
4. Humus. 
Layer silicate clays, iron and aluminum oxide clays, allophane and associated amorphous clays are inorganic colloids while humus is an organic colloid.
Therefore, the correct answer is option B. 

Multiple choice evs mud and stones soil - formation and profile soil-nature soil profile

The soil near the surface is usually darker than about one meter down, this is because the top soil


  1. Is richer in Ca and Mg

  2. Contains more organic matter

  3. Is wetter than the sub soil

  4. Is drier than the sub soil
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

(b) Top soil contains decomposed and amorphous organic matter composing of sand with humus.

Multiple choice evs mud and stones soil - formation and profile soil-nature soil profile

When a small amount of garden soil is put into a glass jar containing water, stirred and allowed to stand for two hours, the layers from top to bottom would be

  1. Debris, water, sand and clay

  2. Humus, water, clay and sand

  3. Debris, clay, gravel and sand

  4. Humus, clay, gravel and sand
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Soil is comprised of air spaces and organic matter, but mostly mineral particles. There are three kinds of soil minerals, sand, silt and clay. The relative percentage of each of these particles in the soil determines its texture. Sand has the largest soil particles (0.4- to 0.01-inch diameter) and the largest pores between particles. Silt soil particle size is between clay and sand (0.01- to 0.0001-inch diameter). The characteristics of silty soil are similar to those of clay, but are moderated by its larger particle size. Clay soil has the smallest soil particles (less than 0.0001-inch diameter) and the least amount of water and air spaces between particles. Humus is dark, organic material that forms in soil when plant and animal matter decays. The thick brown or black substance that remains after most of the organic litter has decomposed is called as humus. Hence, humus settles at the topmost and sand the lowermost since, its size is maximum.

Multiple choice chemistry for a pollution free nature properties of soil soil pollution and its effects soil and soil pollution

Which soil horizon contains humus?

  1. A-Horizon

  2. B-Horizon

  3. C-horizon

  4. Bedrock
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Humus refers to the fraction of soil organic matter that is amorphous and without the cellular cake structure characteristic of plants, micro-organisms or animals. Humus has a characteristic black or dark brown color and is organic due to an accumulation of organic carbon found in Horizon - A. The three major horizons are: (A) surface horizon, (B) subsoil and (C) substratum. Some soils have an organic horizon (O) on the surface. Hard bedrock, which is not soil, uses the letter R.

Multiple choice

Which one of the following is a geographical requirement for growing maize?

  1. Average rainfall of 650mm to 1000mm

  2. rich alluvial soils with an impervious layer to retain water

  3. Optimum temperatures of 16oc

  4. High land with acidic soils
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Maize requires substantial rainfall during its growing season, ideally 650-1000mm annually. This precipitation range supports proper germination, growth, and kernel development without waterlogging or drought stress.

Multiple choice water and mineral resources in tamil nadu tamil nadu agriculture human geography in tamil nadu geography economics

Sivagangai and Ramanathapuram districts in Tamil Nadu have _____ type of soil.

  1. Alluvial

  2. Black

  3. Red loams

  4. Laterite soils
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The red soil is found predominantly in Sivagangai, Virudhunagar, Ramanathapuram, Madurai, Dindigul, Nagapattinam, Thoothukudi, Tirunelveli and the Nilgiris districts in Tamil Nadu. The red or brown colour of the soil is attributed to the diffusion of iron content.

Multiple choice water and mineral resources in tamil nadu tamil nadu agriculture human geography in tamil nadu geography economics

Coimbatore, Madurai, Virudhunagar, Thoothukudi and Tirunelveli districts in Tamil Nadu have ___________.

  1. Alluvial soils

  2. Black soils

  3. Red loams

  4. Laterite soils
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The black clayey alluvium rich soil is known as black cotton soil is found in parts of Coimbatore, Madurai, Dindigul, Thoothukudi and Tirunelveli and in patches in the districts of Kancheepuram, Vellore, Salem, Dharmapuri, Ramanathapuram, Virudunagar and the Nilgiris.

Multiple choice water and mineral resources in tamil nadu tamil nadu agriculture human geography in tamil nadu geography economics

Thanjavur, Thiruvarur, Nagapattinam, Villupuram, Cuddalore, Thirunelveli, and Kanyakumari districts in Tamil Nadu have ___________.

  1. Laterite soils

  2. Saline soils

  3. Alluvial soils

  4. Black soils
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In coastal regions some alluvial deposits are formed due to wave action. Coastal and deltaic areas of Tamil Nadu includes Thanjavur, Nagapattinam, Tiruchirapalli, Cuddalore, Kancheepuram, Tirunelveli, Tuticorin, Kanyakumari and Sivaganga districts have alluvial soils.

Multiple choice water and mineral resources in tamil nadu tamil nadu agriculture human geography in tamil nadu geography economics

The soils of Tamil Nadu may be grouped into _____ types.

  1. Two

  2. Three

  3. Four

  4. Five
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The soils of Tamil Nadu may be grouped into five types. They are:

  1. Alluvial Soils:  The soils develop from the weathering material transported by rivers from their catchment areas and deposited in their basins during floods.
  2. Black Soils:  The soils are residual soils derived from the rocks of Deccan Trap, Rajmahal Trap, ferruginous gneisses and schists under semi-arid conditions.
  3. Red Soil: The soils have developed on crystalline rocks by prolonged weathering in hot climate.
  4. Laterite Soils: The soils are residual soils developed on aluminum-rich rocks e.g. greisze, sandstone, granite and basaltic rocks in regions of high rainfall with alternating wet and dry seasons.
  5. Forest, peat and organic soils: Forest soils develop in areas under heavy forest cover. Peat and organic soils develop in waterlogged, swampy or marshy areas.

Multiple choice zoology environmental factors soil-nature climate factors abiotic components organisms and environment

The part of the biosphere which contains soil is known as 

  1. Pedosphere

  2. Lithosphere

  3. Hygrosphere

  4. Toposphere
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • Pedosphere is an outer layer of earth that contains soil.
  • Lithosphere includes the brittle upper portion of the mantle, crust and Mantles are made of rock or ices. 
  • Hydrosphere contains all the waters on the earth's surface, such as lakes and seas.
  • Troposphere is the lowest layer of the atmosphere, closest to the earth's surface. so option A is a correct answer.
Multiple choice zoology environmental factors soil-nature climate factors abiotic components organisms and environment

Which of the following components of biosphere makes an interface with the soil?

  1. Pedosphere

  2. Troposhere

  3. Atmosphere

  4. Stratosphere
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The pedosphere is the outermost layer of the Earth that is composed of soil and subject to soil formation processes, forming the direct interface between the biosphere, atmosphere, lithosphere, and hydrosphere.