Introduction to soil
Soil – Pedological and Edaphological concepts
Soil science is the study of soil as a natural resource on the surface of the earth including soil
formation, classification and mapping; physical, chemical, biological, and fertility properties of
soils; and these properties in relation to the use and management of soils.
Sometimes terms which refer to branches of soil science, such as pedology (formation,
chemistry, morphology and classification of soil) and edaphology (influence of soil on
organisms, especially plants), are used as if synonymous with soil science. The diversity of
names associated with this discipline is related to the various associations concerned. Indeed,
engineers, agronomists, chemists, geologists, physical geographers, ecologists, biologists,
microbiologists, sylviculturists, sanitarians, archaeologists, and specialists in regional planning,
all contribute to further knowledge of soils and the advancement of the soil sciences.
Soil scientists have raised concerns about how to preserve soil and arable land in a world with a
growing population, possible future water crisis, increasing per capita food consumption, and
land degradation.
Soil occupies the pedosphere, one of Earth's spheres that the geosciences use to organize the
Earth conceptually. This is the conceptual perspective of pedology and edaphology, the two main
branches of soil science. Pedology is the study of soil in its natural setting. Edaphology is the
study of soil in relation to soil-dependent uses. Both branches apply a combination of soil
physics, soil chemistry, and soil biology. Due to the numerous interactions between the
biosphere, atmosphere and hydrosphere that are hosted within the pedosphere, more integrated,
less soil-centric concepts are also valuable. Many concepts essential to understanding soil come
,from individuals not identifiable strictly as soil scientists. This highlights the interdisciplinary
nature of soil concepts.
Soil Science
“The science dealing with soil as a natural resource on the surface of the earth, including
Pedology (soil genesis, classification and mapping), physical, chemical, biological and fertility
properties of soil and these properties in relation to their management for crop production.”
Soil Science has six well defined and developed disciplines
Soil fertility : Nutrient supplying properties of soil
Soil chemistry : Chemical constituents, chemical properties and the
chemical reactions
Soil physics : Involves the study of physical properties
Soil microbiology : Deals with micro organisms, its population,
classification, its role in transformations
Soil conservation : Dealing with protection of soil against physical loss by
erosion or against chemical deterioration i.e excessive
loss of nutrients either natural or artificial means.
Soil Pedology : Dealing with the genesis, survey and classification
Views on Soil (Science)
The term SOIL was derived from the Latin Word “SOLUM” Means FLOOR
or plant growth (to grow crops)
,Definitions
Generally soil refers to the loose surface of the earth as identified from the original rocks and
minerals from which it is derived through weathering process.
Whitney (1892): Soil is a nutrient bin which supplies all the nutrients required for plant growth
Hilgard (1892): Soil is more or less a loose and friable material in which plants, by means of
their roots, find a foothold for nourishment as well as for other conditions of growth”
Dokuchaiev (1900): Russian scientist - Father of soil science - Soil is a natural body composed
of mineral and organic constituents, having a definite genesis and a distinct nature of its own.
Joffe (1936): “Soil is a natural body of mineral and organic constituents differentiated into
horizons - usually unconsolidated - of variable depth which differs among themselves as well as
from the underlying parent material in morphology, physical makeup, chemical properties and
composition and biological characteristics”.
Jenny (1941): Soil is a naturally occurring body that has been formed due to combined influence
of climate and living organisms acting on parent material as conditioned by relief over a period
of time.
Soil as a three dimensional body
Soil is a three dimensional body having length, breadth and depth. They form a continuation over
the land surface and differ in properties from place to place. Its upper boundary is air or water
and lower boundary is the rock lithosphere.
Composition of soil on volume basis (Soil components)
Mineral matter : 45%
, Organic matter : 5%
Soil water : 25%
Soil air : 25%
Soil can be compared to various systems of animals
Digestive system : Organic matter decomposition
Respiratory system : Air circulation & exchange of gases
Circulatory system (blood) : Water movement within the soil
Excretory system : Leaching out of excess salts
Brain : Soil clay
Colour : Soil colour
Height : Soil depth
Approaches of Soil Study
Two Concepts: One treats soil as a natural body, weathered and synthesized product in nature
(Pedology) while other treats soil as a medium for plant growth (Edaphology).
Pedological Approach: The origin of the soil, its classification and its description are examined
in Pedology. (From Greek word pedon, means soil or earth). Pedology is the study of soil as a
natural body and does not focus on the soil’s immediate practical use. A
pedologist studies, examines and classifies soil as they occur in their natural environment.
Edaphological Approach: Edophology (from Greek word edaphos, means soil or ground) is the
study of soil from the stand point of higher plants. Edaphologists consider the various properties
of soil in relation to plant production. They are practical and have the production of food and
fibre as their ultimate goal. They must determine the reasons for variation in the productivity of
soils and find means for improvement.
Soil – Pedological and Edaphological concepts
Soil science is the study of soil as a natural resource on the surface of the earth including soil
formation, classification and mapping; physical, chemical, biological, and fertility properties of
soils; and these properties in relation to the use and management of soils.
Sometimes terms which refer to branches of soil science, such as pedology (formation,
chemistry, morphology and classification of soil) and edaphology (influence of soil on
organisms, especially plants), are used as if synonymous with soil science. The diversity of
names associated with this discipline is related to the various associations concerned. Indeed,
engineers, agronomists, chemists, geologists, physical geographers, ecologists, biologists,
microbiologists, sylviculturists, sanitarians, archaeologists, and specialists in regional planning,
all contribute to further knowledge of soils and the advancement of the soil sciences.
Soil scientists have raised concerns about how to preserve soil and arable land in a world with a
growing population, possible future water crisis, increasing per capita food consumption, and
land degradation.
Soil occupies the pedosphere, one of Earth's spheres that the geosciences use to organize the
Earth conceptually. This is the conceptual perspective of pedology and edaphology, the two main
branches of soil science. Pedology is the study of soil in its natural setting. Edaphology is the
study of soil in relation to soil-dependent uses. Both branches apply a combination of soil
physics, soil chemistry, and soil biology. Due to the numerous interactions between the
biosphere, atmosphere and hydrosphere that are hosted within the pedosphere, more integrated,
less soil-centric concepts are also valuable. Many concepts essential to understanding soil come
,from individuals not identifiable strictly as soil scientists. This highlights the interdisciplinary
nature of soil concepts.
Soil Science
“The science dealing with soil as a natural resource on the surface of the earth, including
Pedology (soil genesis, classification and mapping), physical, chemical, biological and fertility
properties of soil and these properties in relation to their management for crop production.”
Soil Science has six well defined and developed disciplines
Soil fertility : Nutrient supplying properties of soil
Soil chemistry : Chemical constituents, chemical properties and the
chemical reactions
Soil physics : Involves the study of physical properties
Soil microbiology : Deals with micro organisms, its population,
classification, its role in transformations
Soil conservation : Dealing with protection of soil against physical loss by
erosion or against chemical deterioration i.e excessive
loss of nutrients either natural or artificial means.
Soil Pedology : Dealing with the genesis, survey and classification
Views on Soil (Science)
The term SOIL was derived from the Latin Word “SOLUM” Means FLOOR
or plant growth (to grow crops)
,Definitions
Generally soil refers to the loose surface of the earth as identified from the original rocks and
minerals from which it is derived through weathering process.
Whitney (1892): Soil is a nutrient bin which supplies all the nutrients required for plant growth
Hilgard (1892): Soil is more or less a loose and friable material in which plants, by means of
their roots, find a foothold for nourishment as well as for other conditions of growth”
Dokuchaiev (1900): Russian scientist - Father of soil science - Soil is a natural body composed
of mineral and organic constituents, having a definite genesis and a distinct nature of its own.
Joffe (1936): “Soil is a natural body of mineral and organic constituents differentiated into
horizons - usually unconsolidated - of variable depth which differs among themselves as well as
from the underlying parent material in morphology, physical makeup, chemical properties and
composition and biological characteristics”.
Jenny (1941): Soil is a naturally occurring body that has been formed due to combined influence
of climate and living organisms acting on parent material as conditioned by relief over a period
of time.
Soil as a three dimensional body
Soil is a three dimensional body having length, breadth and depth. They form a continuation over
the land surface and differ in properties from place to place. Its upper boundary is air or water
and lower boundary is the rock lithosphere.
Composition of soil on volume basis (Soil components)
Mineral matter : 45%
, Organic matter : 5%
Soil water : 25%
Soil air : 25%
Soil can be compared to various systems of animals
Digestive system : Organic matter decomposition
Respiratory system : Air circulation & exchange of gases
Circulatory system (blood) : Water movement within the soil
Excretory system : Leaching out of excess salts
Brain : Soil clay
Colour : Soil colour
Height : Soil depth
Approaches of Soil Study
Two Concepts: One treats soil as a natural body, weathered and synthesized product in nature
(Pedology) while other treats soil as a medium for plant growth (Edaphology).
Pedological Approach: The origin of the soil, its classification and its description are examined
in Pedology. (From Greek word pedon, means soil or earth). Pedology is the study of soil as a
natural body and does not focus on the soil’s immediate practical use. A
pedologist studies, examines and classifies soil as they occur in their natural environment.
Edaphological Approach: Edophology (from Greek word edaphos, means soil or ground) is the
study of soil from the stand point of higher plants. Edaphologists consider the various properties
of soil in relation to plant production. They are practical and have the production of food and
fibre as their ultimate goal. They must determine the reasons for variation in the productivity of
soils and find means for improvement.
