Environmental Studies · Geography

Soil Science

1,499 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

Which of the following layer of the soil contains more humus?

  1. Top soil

  2. Subsoil

  3. Bedrock

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

Top soil contains detritus micro-organisms  that decompose dead plant and animals and add to the organic content of the soil. The decomposed organic matter is called humus.

So, the correct answer is 'top soil'

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

In addition to the rock particles, the soil contains

  1. Air and water

  2. Water and plants

  3. Minerals, organic matter, air and water

  4. Water, air and plants
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
  • Soil composition refers to the nutrients and various other substances present in the soil. 
  • The basic components of soil are minerals, organic matter, water, and air. The typical soil consists of approximately 45% mineral, 5% organic matter, 20-30% water, and 20-30% air.
  • Hence In addition to the rock particles, the soil contains Minerals, organic matter, air, and water.
  • So, the correct answer is 'Minerals, organic matter, air, and water'.
Multiple choice biology natural resources - air, water and land soil - formation and profile soil-nature soil profile

Deep black soil is considered to be highly productive due to high proportion of

  1. Silt and earthworm

  2. Clay and humus
  3. Gravel and $Ca^{++}$

  4. Sand and Zn
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Deep black soil (often called Regur or Black Cotton soil) is highly productive because it is rich in clay, which retains moisture, and humus, which provides essential nutrients for plant growth.

Multiple choice biology natural resources - air, water and land soil - formation and profile soil-nature soil profile

The top most layer of soil contains

  1. Humus, living organism and soil

  2. Human, living organism and plants

  3. Humans and soil particles

  4. Human and microorganism
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The top most layer of soil is said to contain and support a lot of living organisms. It also has organic manure in it that supports the growth and development of plants. 

So, option a "Humus, living organisms and soil" is the correct answer.

Multiple choice biology natural resources - air, water and land soil - formation and profile soil-nature soil profile

Soil contain rock particles

  1. Water and plants

  2. Minerals, organic matter, air and water

  3. Air and plants

  4. Air, water and plants
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The soil is formed by weathering of rocks. It contains an organic material (dead decay of leaves and plants) called humus, which makes soil fertile, and mineral by the breakdown of rocks. It also contains soil and water. Thus, the correct option is B.
Multiple choice evs mud and stones soil - formation and profile soil-nature soil profile

Identify the constituents of soil.

  1. Gravel

  2. Salt

  3. Mineral

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Soil is a major part of the natural environment, alongside air and water, and is vital to the existence of life on the planet. Soil is the result of the process of the gradual breakdown of rock, the solid geology that makes up the Earth. As rock becomes broken down through a variety of processes, such as weathering and erosion, the particles become ground smaller and smaller.
As a whole, soil is made up from four constituents: mineral material, organic material, air and water. There are considered to be three main mineral parts to soil; ‘sand’, ‘silt’ and ‘clay’. These parts give the soil its 'mineral texture'. In addition, as leaves and other organic material fall to the ground and decompose - there also forms an ‘organic’ layer. Soil scientists (or pedologists) use a series of sieves info to separate out the constituent parts in order to characterise soil by texture class.
Multiple choice evs mud and stones soil - formation and profile soil-nature soil profile

Soil is a mixture of

  1. Sand and clay

  2. Sand and humus

  3. Clay and humus

  4. Sand,clay and humus
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Soil is the upper weathered humus containing part of earth's surface, which can sustain terrestrial plant life. Soil is composed of inorganic mineral particles (45 percent), water (25 percent), air (25 percent), humus (5 percent) and variable number of living organisms. Mineral particles are of four types- (i) gravel or fine pebbles, (ii) sand or silica or quartz, (iii) silt or very fine quartz, (iv) clay or hydrated silicates of aluminium. 

Clay and humus are the main determinants of soil properties. Silt and Sand are chemically inert and do no hold water. Clay and humus produce colloidal complex for holding water and ions and forming soil crumbs.

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

Which of the following present in the soil is most helpful to the growth of plants?

  1. Humus

  2. Sand

  3. Clay

  4. Small porous rocks
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Humus is a type of organic material. It is present inside the soil in the form of a dark-coloured substance. Humus is formed by breaking down of plant litter that includes dried and fallen leaves, branches twigs etc. along with dead bodies of animals and insects. Over a period of time, all these decompose and cause break down of their complex substances into simple ones. It contains some of the important chemicals required for the soil for its nutrient maintenance. 

So, we can say that humus provides nutrients to the soil. Apart from this, in its presence, air and water can percolate through the soil particles easily, increasing its efficiency.
So, option A "Humus" is the correct answer.

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

.......... is a mixture of sand and clay.

  1. Clay

  2. Humus

  3. Silt

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

  • The different types of loam soils each have slightly different characteristics, with some draining liquids more efficiently than others. The soil's texture, especially its ability to retain nutrients and water are crucial.
  • Loam soil is a mixture of soil that is the ideal plant-growing medium. It is actually a combination soil, normally equal parts of clay, silt, and sand, which gives the benefits of each with few of the disadvantages.
So, the correct answer is 'Loam'.

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

.......... soils tend to be light, well aerated and rather dry.

  1. Red soil

  2. Black soil

  3. Sandy soil

  4. Clayey soil
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Sandy soil is made up of constituent particles that are relatively larger in size. The larger size of sandy particles leads to their lesser absorptive surface area. As a result, their water holding capacity is less. Their particles are larger and their inter particular space is more. So, air can move easily between these particles leading to proper aeration.  

All other soil types like red soil, black soil, and clayey soil have smaller particles and more absorptive surface area.

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.