Soil Resources
ICSE Class 10 · Geography · Chapter 6
What this chapter covers
- Soil as a resource
- Mode of formation of soil
- Composition and characteristics of soil
- Types of soil in India
- Alluvial soil
- Black soil
- Red soil
- Laterite soil
- Comparing the four soils
- Soil erosion — meaning and agents
- Soil erosion — causes
- Soil conservation — importance
- Soil conservation — methods
- Common mistakes to avoid
Key points
- Soil is the loose top layer of the earth, made of weathered rock, humus, water and air; it supports plant life and forms very slowly.
- Soil formation depends on parent rock, climate, relief, living organisms and time; climate is the strongest factor.
- A typical soil is about 45 per cent minerals, 5 per cent organic matter, 25 per cent water and 25 per cent air.
- Soils are described by colour, texture, minerals and the crops they support.
- Alluvial soil is transported river sediment covering the northern plains and deltas; it is rich in potash and lime, poor in nitrogen and phosphorus, and grows rice, wheat, sugarcane and jute.
- Khadar is new, fertile alluvium on flood plains; bhangar is old alluvium above flood level and contains kankar.
- Black soil (regur) forms from Deccan basalt; it is clayey, moisture-retentive and self-ploughing, rich in lime and iron, poor in nitrogen, and best for cotton.
- Red soil forms from granite and gneiss; it is red from iron oxide, sandy to loamy and porous, poor in nitrogen, phosphorus and humus, and grows millets, pulses and groundnut.
- Laterite soil forms by intense leaching under heavy rainfall and high temperature; it is rich in iron and aluminium, poor in most nutrients, hardens like brick, and supports tea, coffee, rubber and cashew when manured.
- Soil erosion is the removal of topsoil by running water and wind faster than new soil can form; water erosion moves from sheet to rill to gully erosion.
- Human causes of erosion include deforestation, overgrazing, faulty farming, shifting cultivation, mining and construction.
- Soil conservation protects food supply, livelihoods, rivers and dams, and is achieved by afforestation, contour ploughing, terrace farming, strip cropping, shelter belts, gully plugging, crop rotation and controlled grazing.
Questions answered
Define soil.
Soil is the thin, loose upper layer of the earth's surface, made of weathered rock particles mixed with decayed organic matter, water and air, in which plants can grow.
Name four factors that influence the formation of soil.
Parent rock, climate, relief, and living organisms; time is a fifth factor.
Distinguish between residual and transported soil, giving one example of each.
A residual soil forms at the place where its parent rock was weathered, for example black soil on the Deccan basalt. A transported soil is made of particles carried by rivers, wind or glaciers and deposited elsewhere, for example alluvial soil of the northern plains.
What is meant by soil texture? Why does texture matter to a farmer?
Soil texture is the relative proportion of sand, silt and clay in a soil. It decides how well the soil drains and holds water, how easy it is to plough and how well it holds nutrients.
State two differences between khadar and bhangar.
Khadar is new alluvium renewed by floods every year and found on low flood plains near rivers; bhangar is old alluvium on higher ground above flood level. Khadar is finer and more fertile, while bhangar is less fertile and contains kankar nodules.
Name the parent rock of black soil and two states where black soil is found.
Basalt of the Deccan Traps; black soil is found in Maharashtra and Gujarat (also western Madhya Pradesh and northern Karnataka).
Why is black soil suitable for growing cotton without irrigation?
Black soil is clayey and has a very high capacity to retain moisture, so it stays moist long after the rains end and supplies water to the cotton crop through its long growing season.
Give the reason for the colour of red soil. Why does it sometimes appear yellow?
Red soil is red because iron oxide is widely diffused through it. It appears yellow where the iron oxide is in a hydrated form.
Past board exam questions
ICSE 2027 sample paper · 1 mark
Black soil : Maharashtra :: Red soil : __________.
- Uttar Pradesh
- Bihar
- Odisha
- Punjab
Show answer
Odisha
ICSE 2027 sample paper · 2 marks
Explain how conservation of soil helps in the conservation of the following: (a) Forests (b) Groundwater reserve
Show answer
(a) Soil is the medium in which plants grow; conserving soil lets trees grow and forests develop and regenerate.
(b) A soil cover, especially under vegetation, allows rainwater to infiltrate and collect underground, so conserving soil helps recharge the groundwater table.
ICSE 2027 sample paper · 2 marks
State any two similarities between red soil and laterite soil.
Show answer
Any two: both are reddish in colour due to iron oxides; both are generally infertile / poor in nitrogen and humus; both are porous and cannot retain moisture; both are acidic; both are coarse in texture; both are in-situ (residual) soils.
ICSE 2027 sample paper · 3 marks
With reference to Black Soil, answer the following questions: (a) How does its mode of formation determine its name? (b) Mention two minerals that this soil is rich in. (c) Why is this soil called an in-situ soil?
Show answer
(a) Black soil is formed by the weathering of dark-coloured basaltic lava rocks of the Deccan; the dark parent rock gives the soil its black colour and hence its name.
(b) Any two: lime (calcium), potash, iron, magnesium.
(c) It develops at its place of origin, over the parent rock from which it is formed, and is not transported.
ICSE 2027 sample paper · 3 marks
Give a reason for each of the following statements: (a) Farmers prefer soil that is rich in humus. (b) Rice can be cultivated in red soil only if irrigation is provided. (c) Khadar soil can hold more moisture than Bhangar.
Show answer
(a) Humus (decayed organic matter) adds nutrients and fertility to the soil and improves its moisture retention, increasing crop yield.
(b) Rice needs clayey soil that holds standing water; red soil is coarse, porous and cannot retain moisture, so water must be supplied by irrigation.
(c) Khadar (new alluvium) is finer, more clayey and compact, so it retains moisture, whereas Bhangar (old alluvium) is coarser and contains lime nodules (kankar).
ICSE 2026 sample paper · 1 mark
On the outline map of India provided: Shade and label an area of black soil in Gujarat.
Show answer
Shade the Kathiawar peninsula / the area around Surat–Bharuch–Vadodara in Gujarat (Deccan Trap region) and label it 'Black soil'.
ICSE 2026 board paper · 1 mark
Choose the characteristic that is true about Laterite soil.
- It is a clayey soil.
- It is moisture retentive.
- It is rich in calcium.
- It undergoes desilication.
Show answer
It undergoes desilication.
ICSE 2026 sample paper · 1 mark
Ex-situ soil found in India is __________.
- Alluvial soil
- Black soil
- Laterite soil
- Red soil
Show answer
Alluvial soil