Soil Resources — Part 2: Soil erosion and conservation: visual lesson, ICSE Class 10 Geography (H.C.G. Paper 2)

Lesson

When the soil walks away

Part 2 — a centimetre of fertile topsoil can take hundreds of years to form, yet one violent storm can strip it from a bare slope in an afternoon. Protecting soil is protecting food.

In this lesson you will

Explain sheet, gully and wind erosion
Identify human causes of soil erosion such as deforestation and overgrazing
Describe terrace farming, contour ploughing, shelter belts and afforestation and say where each suits
Interpret illustrative data on soil loss under different methods

Table of agents of soil erosion and the kinds of place where each is most active
Agent	Where it does most damage
Running water	Bare slopes, ravine lands of the Chambal
Wind	Dry sandy lands of western Rajasthan
Waves	Coasts
Glaciers	High Himalaya

Concept

Soil erosion and its types

Soil erosion is the removal of the top layer of soil by natural agents, faster than new soil can form. Sheet erosion: running water removes a thin, even layer of topsoil from a large area; it is hard to notice until the land loses fertility. Gully erosion: water running down slopes cuts deep channels (gullies); they widen and join until the land becomes ravines — the Chambal valley of Madhya Pradesh, Rajasthan and Uttar Pradesh is a well-known example. Wind erosion: strong winds blow away loose, dry, bare soil, as in western Rajasthan.

Concept

Human causes of soil erosion

Deforestation: tree roots bind soil and leaves break the force of rain; cutting forests on hill slopes exposes the soil. Overgrazing: too many cattle, sheep and goats eat grass down to the roots and their hooves loosen the soil, as on many Himalayan and Aravalli slopes. Faulty farming: ploughing up and down slopes, leaving fields bare after harvest, and shifting cultivation (jhum) on north-eastern hills. Other: mining, quarrying, road building and construction strip the land of its cover.

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