Soil Flashcards
what are the factors affecting soil fertility?
moisture
nutrients- phosphorous nitrogen potassium etc.
depth of soil
organic matter or humus.
what is in-situ soil?
soil which is formed at original loc. by breaking of parent rock.
also called residual/sedimentary soil.
have well defined soil profile.
e.g. black, red, laterite, sandy desert soil.
what is ex-situ soil?
soil which is formed by sediments transported by wind, water etc.
also called transported soil
do not have well defined soil profile.
e.g. alluvial soil.
brief note on alluvial soil.
transported, loamy soil
covers 40% land mass.
also called riverine soil.
found in entire northern plains, deltas of mahanadi godavari krishna and kaveri
what is loam?
a mixture of clay silt and sand.
what is Khadar?
newer deposits of soil closer to the river banks.
has finer particles of silt and clay and is light in color.
is more fertile as new deposits are added every year.
it lies below flood levels of river.
what is Bhangar?
older alluvial soil which is not as fertile as khadar
occupies maximum portion of northern plains
is above flood levels of river
has lime nodules called kankar
where is inland alluvium found?
Indus, ganga, Brahmaputra plains,
Bangladesh, Assam, Punjab, Haryana, UP,, Bihar
Gujrat, few patches of Rajasthan.
where is deltaic alluvium found?
deltas of ganga-Brahmaputra, mahanadi, godavari, krishna, kaveri
where is coastal alluvium found?
tidal origin
coastal strips of India, plains of Gujrat.
color and texture of alluvial soil
colour- light grey to deep black depending on depth, texture and time of maturity.
texture- upper reaches are dry coarse porous
lower plains- small/fine particles, uniform, compact.
minerals found in alluvial soil
rich in - iron, magnesia, potash, lime
lack- phosphorous nitrogen humus.
only ganga plains soil has humus.
soil in drier regions is basic in nature.
what are the crops grown in alluvial soil.
rice, wheat, sugarcane, oilseeds, jute(lower G-B plains), cotton, tobacco
brief note on black soil.
residual, clayey soil
formed by denudation of volcanic rocks
found along the deccan lava tract - i.e. Maharashtra, Gujrat, Andhra Karnataka T.N.
also called black cotton soil or regur soil.
color and texture of black soil
colour- black made out of igneous rocks
texture- fine, clayey, highly water retentive,
how is black soil self ploughing?
due to high water retentivity, it absorbs moisture in monsoon and expands.
in dry season it shrinks and cracks up
these cracks allow entry of oxygen and water into the soil. cracks get filled up in the rains.
minerals found in black soil.
high- iron, magnesia, lime
low- nitrogen, phosphorous, humus.
crops grown in black soil
cotton, wheat, jowar, linseed, sugarcane, tobacco
why is black soil good for dry farming?
water is always present in subsoil of black soil.
brief note on red soil.
second largest soil group after alluvial soil
made from denudation of old crystalline rocks by rainfall.
found in the peninsular region of india surround in the black soil region.
bundelkhand (n)
Rajmahal hills(e)
kutch(w)
Tamil nadu(s)
color and texture of red soil.
residual loamy soil
red color due to Fe2O3.
porous loose aerated shallow
what are the minerals in red soil
poor- N, P, Na, humus, soluble salts.
how can farming be done in red soil.
red soil is not very fertile, but it responds well to fertilizers.
it needs irrigation.
what kind of crops are grown in red soil?
vegetables, ragi, tobacco,
higher land- coarse soil- potato ground nut
lower land- clayey soil- sugarcane.
Brief note on laterite soil.
residual soil formed by leeching.
found in regions of heavy rains, high temperature, alternate wet and dry periods- i.e. M.P. Odisha, Andhra, Telangana Kerala, Karnataka, T.N.
what is leeching.
percolation of nutrients below the soil due to tropical rainfall which leaves the top soil infertile.
color and texture of laterite soil
red color due to presence of Fe2O3
texture- porous, coarse and friable(easy to crumble)
minerals in laterite soil.
potash is removed due to leeching.
poor- lime, magnesia, N
acidic in nature.
crops which can be grown in laterite soil
with sufficient manuring and irrigation-
cashew, tea, coffee, ragi, sugarcane.
lowland laterite- paddy
upland laterite- tea, cinchona, rubber
define soil erosion
removal of top soil thus making the land infertile.
sheet erosion
removal of thin layer of soil on gentle slopes where vegetation is absent
rill erosion
deposition of soil that is carried away in the form of finger shaped rills over large areas
gully erosion
removal of heavy load of soil due to heavy rainfall on barren land making the soil unproductive.
shore erosion
erosion on sea shores due to waves.
stream bank erosion
soil removed from banks of river when river changes its coarse.
wind erosion in particle size- >0.5 mm
rolling- called soil creep
wind erosion in particle size- 0.1 to 0.5 mm
bouncing and hopping- called saltation
wind erosion in particle size- < 0.1 mm
suspension- causes dust storms (sand gets deposited along fenced roads)
man made causes of soil erosion
overpopulation- causes deforestation, clearing of land for food.
overgrazing- leads to lack of vegetation, expose soil to agents of denudation.
bad farming techniques- impropper use of manure/fertilizers, traditional ploughing methods, methods like slash and burn etc.
natural causes of soil erosion
presence of steep slopes
erratic rainfall causing alternate wet and dry seasons.
extremely heavy rainfall washes away topsoil.
list out the regions of India affected by soil erosion.
badlands of chambal and yamuna peidmont zone of west himalaya CNP region Tapi-Sabarmati valley regur soil region of maharashtra dry parts of rajasthan, gujrat haryana steep slopes of western ghats
soil conservation
prevention of soil loss or soil fertility by over usage, acidification, saltation etc.
what are the harmful effects of soil erosion
lowering of water table
decreased moisture in soil
floods due to rivers getting plugged with silt.
reduced soil fertility
increasing landslides
bad effects on economic prosperity and cultural development.
what is terrace farming
cutting slopes in a step like manner for cultivation, terrace acts like bunds and prevents top soil from washing away.
what are shelter belts.
planting trees in rows to prevent wind erosion (wind breaks)
what is contour farming
ploughing around hills in circles for agriculture prevents run off.
what is strip cropping
two different crops are grown in alternate strips to maintain soil fetility
give examples of common crops that are paired and planted in strip cropping
- hay and wheat
2. corn, soy beans, and cotton
how does building dams prevent soil erosion
building dams on the upper coarse of rivers controls flow of rivers during heavy rains and reduces soil erosion by preventing chances of floods.
how does planting trees help in reducing soil erosion
roots of trees hold firmly onto the soil preventing erosion. this can be helpful if trees are planted along the edges of fields.
