Soils

Question 1

Alluvial Soil properties

Answer 1

Most widely spread and imp.
Deposited by Indus, Ganga, Brahmaputra.
Various proportions of sand, silt and clay.
Upper rice valley- coarse soil (piedmont plains like Duar, Chos and Terai)
Old alluvial (Bangar) and new alluvial (Khadar). Bangar has more kanker modules but Khadar is more fertile.
Fertile, adequate proportion of potash, lime, phosphoric acid.
More alkaline in drier areas.

Question 2

Black soil properties

Answer 2

‘Regur’ and ‘black cotton soils’
Climatic cons. and parent rock is main factor
Clayey matrerial
Hold moisture
Euch in soil nutrients (CaCO3, Mg, Potash and lime.
Develop deep crack in hot weather (aeration)
Sticky when wet
Diff. to work with unless filled before.

Question 3

Red and Yellow soils property

Answer 3

Develops on crystalline igneous rocks in areas of low rainfall
Reddish colour due to diffusion of iron in crystalline and metamorphic form.
Yellow when in hydrated form.

Question 4

Laterite soils property

Answer 4

'Later' means brick
High temp. and heavy rainfall
Intense heavy leaching due to rain
Humus is low
Suitable for cultivation with chemicals and fertilisers

Question 5

Arid soils properties

Answer 5

Range from red to brown
Sandy in Textur and Saline
Evap is faster and lacks humus and moisture
Lower horizons with kanker
Kanker layers at bottom may restrict infiltration of water

Question 6

Forest soils conditions

Answer 6

Found where sufficient rainforests are
Texture varies with mountain formed on
Loamy and silty in valley sides and coarse grained in upper slips
Experience denysstion
Acidic with less humus