India’s Soils and Natural Vegetation Quiz: Clerkship 2024

Black soil holds moisture for long and contains lime, iron and magnesium, which cotton likes, so it is also called 'black cotton soil'. Desert soil cannot hold water.

Black soil is called Regur. Khadar and Bhangar are two kinds of alluvial soil, not names of black soil.

Red soil forms from weathered granite and gneiss and contains iron oxide, which gives the colour. It is actually poor in humus and lime.

Heavy rain with alternating wet and dry spells washes out lime and silica, leaving iron and aluminium. This leaching creates laterite. Alluvium and black soil do not form that way, and deserts get little rain.

Old alluvium on higher banks is Bhangar and has kankar (lime nodules). New alluvium deposited by each flood is Khadar and is more fertile.

The Sundarbans is a mangrove forest standing in tidal saline water, with sundari as the main tree. Deciduous forests grow on drier non-saline land, thorn scrub in low rainfall, coniferous forests in the Himalaya.

Sal and teak grow in monsoon regions with 70–200 cm rain and shed leaves in the dry season to save water. Evergreen forests get over 200 cm.

Thorn scrub grows where rainfall is below 70 cm: long roots, small or spiny leaves to reduce water loss. The Duars, Sundarbans and Kerala coast have plenty of rain or water.

In the cold higher Himalaya conifers grow: deodar, pine and fir. Their needle-like leaves let snow slide off. The other three types belong to warm or saline regions.