This slide is about the various types of soils found in Assam. It gives a highlight on various characteristics of soils, their pH value, deficiency and the places where they occur.

1. Dr. BEEJATA DAS
ASSISTANT PROFESSOR
DEPARTMENT OF GEOGRAPHY
S.P.P. COLLEGE NAMTI, SIVASAGAR,
ASSAM, INDIA

2. Introduction
Soil is the thin surface- layer on the earth comprising
mineral particles formed by the break- down of rocks,
decayed organic materials, living organisms, water and
soil.
Importance of Soil
Soil is a very important natural resource of Assam
because agricultural production is basically dependent on
the fertility of soil.

3. Factors affecting soil formation
Geology, topography and climate
seem to play vital roles in the soil
formation of Assam.

4. GROUPS OF SOIL
ALLUVIAL
SOILS
PIEDMONT
SOILS
HILL
SOILS
LATERITIC
SOILS
YOUNGER
ALLUVIAL
OLDER
ALLUVIAL
RED
SANDY
SOILS
RED
LOAMY
SOILS

5. ALLUVIAL SOILS
These soils are by far the largest and the
most important soil group of Brahmaputra
and Barak Plain. Alluvial soils are developed
from the deposition of the products of
weathering of rocks constituting the
Himalayas by the river Brahmaputra. They
are acidic in reaction. Soils on the northern
bank of the Brahmaputra are less acidic than
those on the southern bank.

6. The alluvial soils contain moderate
amounts of organic matter and nitrogen
and high amounts of phosphorous and
potash. Soils of the Barak valley contain
more humus then those of the
Brahmaputra valley. The soils of the
Brahmaputra valley are richer in total
magnesium.

7. NEWER OR YOUNGER ALLUVIAL SOILS
These soils are found in the north and south bank plains
including the active flood plains of the Brahmaputra and
Barak rivers.
Colour: They are moderately deep to very deep and grey
to molted grey.
Texture: They are mostly sandy to silty loams. The new
alluvial soils of the Brahmaputra valley are of a coarser
texture while soils of the Barak valley are of a finer
texture.

8. pH: These soils are less acidic
and are often neutral in
reaction.
Deficiency: They are deficient
in phosphoric acid, nitrogen
and humus.

9. OLDER ALLUVIAL SOILS
This soil occurs in some patches of Kokrajhar, Barpeta,
Nalbari, Kamrup, Darrang, Sonitpur, Lakhimpur and
Dhemaji districts between the northern piedmont soil belt
and the southern new alluvial soils of the Brahmaputra
valley. It occurs in a narrow belt in the south bank districts
of the Brahmaputra valley. In the Kopili plain covering
Nagaon district the old alluvium finds wider extension,
Barak plain also has some elongated patches of old
alluvium confined between the new alluvial soils of the
active floodplain and the hill soils bordering Mizoram.

10. Colour: These soils are very deep, brownish
to yellowish brown in colour.
Texture: They are mostly fine loams to
coarse loams.
pH: These soils are slightly to moderately
acidic.

11. PIEDMONT SOILS
The piedmont soils comprise the Bhabar and the Tarai soil covering
respectively the Bhabar and Tarai belt of the Brahmaputra valley.
Occurrence: These soils are confined to the northern narrow zone
along the piedmone zone of the Himalayan foothills. The Bhabar
soil occurs in the narrow Bhabar zone along Assam- Arunachal
border extending east upto the river Subansiri. The Tarai soil occurs
just south of the Bhabar soils extends upto the Dihang river in some
discontinuous narrow patches.

12. Colour: The Bhabar soil is deep to very
deep in colour.
Texture: The Bhabar soil is coarse loamy
in texture whereas the Tarai soils varies
from sandy to slity loams that remain
saturated.

13. HILL SOILS
Occurrence: They are found in the southern hilly terrains
of the state.
RED SANDY SOILS
Occurrence: They are found in a narrow belt along the
Assam- Meghalaya border, the Karbi Plateau, southern
part of the Barail ranges of Dima Hasao district and some
parts of the foothills along the eastern border of the
Cachar district.

14. Colour: They are very deep, well drained
and brownish to yellowish red in colour.
Texture: The texture of these soils varies
from sand to clay.
Deficiency: These soils are poor in lime,
manganese, phosphates, nitrogen and
humus.

15. RED LOAMY SOILS
Occurrence: These soils occur in the narrow
southern foothill belt running along Assam’s
border with Arunachal and Pradesh Nagaland and
also in the southern fringes of the Karbi Plateau
and the Barail hills of Dima Hasao district also
along the Assam- Mizoram border.

16. Colour: They are deep, dark grayish
brown to yellowish red in colour.
Texture: These soils are fine to coarse
loamy in texture.
pH: They are lightly to moderately
acidic.
Deficiency: These soils lack in nitrogen,
phosphoric acid, humus and lime.

17. LATERITIC SOILS
Occurrence: These soils occur extensively almost
over the Dima Hasao district covering some parts
of southern Karbi Plateau while few patches are
confined to eastern margin of the Hamren sub-
division of Karbi Anglong district, southern border
of Golaghat district and the northern part of the
Barak Plain along the foothills of the Barail range.

18. Colour: These soils are dark in colour.
Texture: They are finely textured with
heavy loams.
Deficiency: These soils are deficient in
nitrogen, potash, phosphoric acid and
lime.

19. REFERENCES
Bhagabati, A.K., et al. (2007).Geography of Assam, Rajesh
Publications, New Delhi.
Khullar, D.R. (2005). India- A Comprehensive Geography,
Kalyani Publishers, New Delhi.
Kolay, A.K. (1993). Basic Concepts of Soil Science, Wiley
Eastern Limited, New Delhi.