2. Contents
Soil
Factors of soil formation
Factors controlling the rate of soil formation
Geology
Rock type
Rock structure
Climate
Soil profile
Soil conservation and its types
Farmland Conservation
Conservation Tillage
Counter Bunding
Cover Crops
Methods of Soil Conservation
World Wide organizations for soil conservation
Soil Science Society of Pakistan (SSSP)
3. Soil
Soil is defined as the top layer of the earth’s
crust.
Formed by mineral particles, organic matter,
water, air and living organisms.
It is in fact an extremely complex, variable and
living medium.
Soil has a role as a habitat and gene pool, serves
as a platform for human activities, landscape
and heritage and acts as a provider of raw
materials.
These functions are worthy of protection
because of their socio-economic as well as
environmental importance
6. Factors of Soil formation
Parent material
Geologic material in which a soil forms.
Climate
Through effects of precipitation and temperature, climate affects the rates of biological l, chemical
and physical processes involved in soil formation.
Organisms
Living organisms are responsible for accumulation of organic matter, nutrient cycling and profile
mixing.
Topography
Landscape relief modifies the effects of organisms and climate on soil development.
Time
Effects of climate and living organisms, modified by topography, on the
development of soil from parent material takes time. Effect of time can be seen by
looking at chronosequences in Mississippi and Red River alluvium.
7.
8. Factors controlling the rate of soil
formation
Geology
The local geology and its interaction with climate largely
determines the nature and type of soil that occurs at ground surface.
Rock type
Igneous
Sedimentary
Metamorphic
Rock structure
The rock structure is the result of processes that have impacted on the
rock after deposition
Climate
Climate is of considerable influence to erosional and weathering
processes
9. Soil profile
• Soil formation begins first with
the break down of rock into
regolith. Continued weathering
and soil horizon development
process leads to the development
of a soil profile, the vertical
display of soil horizons.
10. Horizons of Soil
O Horizon
At the top of the profile is the O horizon. The O horizon is primarily composed of organic
matter.
A Horizon
The A horizon marks the beginning of the true mineral soil. In this horizon organic material
mixes with inorganic products of weathering. The A horizon typically is dark colored horizon
due to the presence organic matter.
E Horizon
The E horizon generally is a light-colored horizon with eluviation being the dominant
process. Leaching, or the removal of clay particles, organic matter, and/or oxides of iron and
aluminum is active in this horizon.
B Horizon
The B horizon is a zone of illuviation where downward moving, especially fine material, is
accumulated. The accumulation of fine material leads to the creation of a dense layer in the
soil.
C Horizon
The C horizon represents the soil parent material, either created in situ or transported into its
present location. Beneath the C horizon lies bedrock.
11. Soil conservation
Soil conservation is a set of management strategies for prevention
of soil being eroded from the Earth’s surface or becoming chemically
altered by overuse, acidification, salinization or other chemical soil
contamination.
Following are the types of soil conservation:
Farmland conservation
Conservation Tillage
Contour Bunding and Bench Terracing
Cover Crops
12. Farmland conservation
Farmland conservation techniques such as
contour planting, crop rotation and strip
planting re-energize soil content and prevent
erosion.
13. Conservation Tillage
Conservation tillage practices like strip-tilling,
no-tilling, ridge-tilling and mulch-tilling leave
a good portion of nutrient-rich organic
material in place and conserve topsoil.
14. Contour bunding
Contour bunding and bench terracing are
effective soil conservation techniques.
Bunding protects land from water runoff, and
bench terracing recycles organic matter from
one terrace to the next.
15. Cover Crops
Planting cover crops like oats, wheat or rye on
unused land builds organic matter while
protecting topsoil from wind and water
erosion.
17. World Wide organizations for soil
conservation
World Association of Soil and Water Conservation
(WASWC)
International Soil Conservation Organisation (ISCO)
Soil and Water Conservation Society (SWCS) 1943
18. Soil Science Society of Pakistan
(SSSP)
The Soil Science Society of Pakistan (SSSP) is a non-
government and non-profit organization of scientists,
engineers, technologists and students involved in the
profession of Soil Science. The Society, established in
1958, was revived in 1984. Active members of the Society
are over 400.