NCERT Solutions For Class 11 Geography Chapter 18 Soils

(i)       Black soil is made up of volcanic rocks and lava-flow. It covers most of the Deccan Plateau that includes parts of Maharashtra, Chhattisgarh, Gujarat, Madhya Pradesh, Telangana, Andhra Pradesh and some parts of Tamil Nadu. These soils are also known as the ‘Regur Soil’ or the ‘Black Cotton Soil’. It consists of Lime, Iron, Magnesium and also Potash but lacks in Phosphorus, Nitrogen and Organic matter. These soils are clayey, deep and impermeable. Black soil retains the moisture for a very long time and even during the dry season. The colour of the soil ranges from deep black to grey.

(ii)      Soil conservation is a methodology to maintain soil fertility, prevent soil erosion and exhaustion and improve the-degraded condition of the soil.

Following methods can be adopted to check erosion and to conservation of soil:

• To check open cultivable lands on slopes from farming
• Lands with a slope gradient of 15 - 25 percent should not be used for cultivation
• Over-grazing and shifting cultivation should be regulated and controlled
• New trees are to be planted in areas of soil erosion and old ones are to be protected.
• Shifting agriculture should be completely banned
• Contour bunding, Contour terracing, regulated forestry, controlled grazing, cover cropping, mixed farming and crop rotation are some of the remedial measures which are often adopted to reduce soil erosion.

(iii)    Soil fertility refers to the ability of a soil to sustain plant growth. Alluvial soils of the Northern India and Black Soils of the Deccan Trap are some of the examples of fertile soils.

A fertile soil has the following properties:

• It is rich in nutrients including nitrogen, phosphorus and potassium
• It contains sufficient minerals like boron, chlorine, cobalt, copper, iron, manganese, etc.
• It contains soil organic matter
• Good soil structure
• A range of microorganisms that support plant growth.

Naturally fertile soils are capable to produce more crops year after year without much help of chemical fertilizer. Culturally induced fertility is that fertility, which has been added to the soil by the farmers. Chemical fertilizers are originated through synthetic means, and contain one or more of the essential growth nutrients such as nitrogen, phosphorus, and potassium and various others. Chemical fertilisers reduce fertility of soil in the long run.

(i)       Soil is the mixture of minerals, organic matter, gases, liquids, and the countless organisms that live together to support life on Earth.

(ii)      The major factors affecting the formation of soil are relief, parent material, climate, vegetation, other life-forms and time. Besides these, human activities also influence it to a large extent.

(iii)     There are three horizons of soil profile.

Horizon A is the topmost zone, and contains mineral matter, nutrients and water, which are necessary for the growth of plants.

Horizon B contains matter derived from below as well as from above.

Horizon C is composed of the loose parent material.

(iv)     Soil degradation is the decline in soil quality caused by its improper use, usually for agricultural, grazing, industrial and infrastructural purposes.

(v)      Khadar is the new alluvium and is deposited by river during floods, which enriches the soil by depositing fine silts and good for intensive cultivation. Bhangar represents a system of older alluvium, deposited away from the flood plains and often seen in the structure of terrace. Both the soils contain calcareous concretions, locally know as Kankars.

(i) (a) Alluvial Soil   ✓

(ii) (c) Black Soil   ✓

(iii) (b) Water erosion   ✓

(iv) (c) Over irrigation   ✓