Resources and Development Test - 24

Most desert soils are called Aridisols (dry soil). These are porous sandy soils with low nitrogenous matter and humus. These are saline in nature too.

Deserts cover 20 to 33% of the Earth’s land surface, and can be found in the tropics, at the poles, and in between. Desert soils are formed where there is scanty rainfall.

Great civilizations are flourished in the areas having alluvial soil and water bodies. Alluvial soils and irrigation facilities produce abundant crop yield.

Alluvium is a loose soil or sediments which are formed by erosion by rainwater. It is typically made of small particles of silt and clay and larger particles of sand and gravel.

Wind erosion refers to the movement and deposition of soil particles by wind. It occurs when soil devoid of vegetation is exposed to high velocity of wind. Rajasthan is the region facing the highest levels of soil erosion due to the dry winds present in the region.

Mountain soils are found in Jammu and Kashmir, Uttar Pradesh, and West Bengal in the Himalayan mountain regions. They are rich in humus and in the drier areas of deciduous forest belt, brown soils are found. They are very good for orchard crops.

These brown forest soils are called Podzol of deciduous forests.

 Ploughing in a wrong way i.e. up and down the slope form channels for the quick flow of water leading to soil erosion. 

This is the most widely spread and important soil. The alluvial soil consists of various proportions of sand, silt and clay. Alluvial soils as a whole are very fertile. Mostly these soils contain adequate proportion of potash, phosphoric acid and lime.

 The laterite soil develops in areas with high temperature and heavy rain. This is the result of intense leaching due to heavy rain. Humus content of the soil is low because most of the micro organisms, particularly the decomposers, like bacteria, get destroyed due to high temperature. 

Soils form from the interplay of five main factors namely Parent material, Time, Climate, Relief and Organisms.

Answer: A- 3; B- 4; C- 1; D- 2

Land use: Land is used for different purposes such as agriculture, forestry, mining, building houses, roads and setting up of industries. This is known as land use.

Humus: Humus is defined as black organic matter formed in soil due to the decay of dead plant and animal matter.

Rock dams: These are the artificial embankments created by constructing mould of soil, clay, sand and rock. Main function is to prevent floods and soil erosion

Arable land: It is the land suitable for agriculture.