What is soil

1. What is soil?
You have 3 minutes to develop a
group consensus definition.

2. Merriam-Webster Online Dictionary
Main Entry:
3
soil, noun
1 : firm land : EARTH
2 a : the upper layer of earth that may be dug or
plowed and in which plants grow b : the
superficial unconsolidated and usually weathered
part of the mantle of a planet and especially of the
earth
3 : COUNTRY, LAND <our native soil>
4 : the agricultural life or calling
5 : a medium in which something takes hold and
develops

3. Wikipedia – The Free Encyclopedia
http://en.wikipedia.org/wiki/Soil
Soil is material capable of supporting plant
life. Soil forms through a variety of
soil formation processes, and includes
weathered rock "parent material" combined
with dead and living organic matter and air.
Soils are vital to all life on Earth because
they support the growth of plants, which
supply food and oxygen and absorb
carbon dioxide and nitrogen.

4. OneLook Dictionary Search
http://onelook.com/?w=soil&ls=a
Quick definitions (soil)
noun: the part of the earth's surface consisting of humus
and disintegrated rock
noun: the geographical area under the jurisdiction of a
sovereign state (Example: "American troops were
stationed on Japanese soil")
noun: material in the top layer of the surface of the earth
in which plants can grow (especially with reference to its
quality or use) (Example: "Good agricultural soil")
noun: the state of being covered with unclean things
verb: make soiled, filthy, or dirty (Example: "Don't soil
your clothes when you play outside!")

5. discoveryschool.com
What’s the difference between soil and dirt? Dirt is
what you find under your fingernails. Soil is what
you find under your feet. Think of soil as a thin
living skin that covers the land. It goes down into
the ground just a short way. Even the most fertile
topsoil is only a foot or so deep. Soil is more than
rock particles. It includes all the living things and
the materials they make or change.

6. discoveryschool.com, cont’d
There is no soil on Mars or Venus. How come?
Those planets have plenty of rocks. Mars has
windstorms that erode rocks into dust. Venus has
an acid atmosphere that cooks rocks into new
chemicals. But there's still something missing.
Without life, there is no soil. Living things haven't
just made a home in the soil on our planet. Life
actually made the soil as we know it.

7. Definitions (simplified)
Soil is a dynamic, heterogeneous, three-phase,
porous media
Perspective: Soil Physics
Soil is the outer layer of the earth’s crust capable of
supporting plant growth (Pearson, 1967, Principles
of Agronomy)
Perspective: Botany, Agronomy, Horticulture, ...
Soil is unconsolidated, surficial material.
Perspective: Geology, Engineers

8. Definitions, Byers, et al., Formation of Soil, 1938*
Soils are natural media for the growth of plants.
They are mixtures of fragmented and partly or
wholly weathered rocks and minerals, organic
matter, water, and air, in greatly varying
proportions, and have more or less distinct layers or
horizons developed under the influence of climate
and living organisms…Soils are dynamic in
character …the product of the action of climate and
living organisms upon the parent material, as
conditioned by the local relief.
*Yearbook of Agriculture

9. Definitions, Simonson, What Soils Are, 1957*
The soil is the link between the rock core of the
earth and the living things on its surface. It is the
foothold for the plants we grow.
The soil mantle of the earth is far from uniform, but
all soils have some things in common.
Every soil consists of mineral and organic matter,
water, and air …
Every soil occupies space ...
Every soil has a profile …
*Yearbook of Agriculture

10. Definitions, Hillel, Introduction to Soil Physics, 1982
Soil refers to the weathered and fragmented outer
layer of the earth’s terrestrial surface.
The soil is a heterogeneous, polyphasic, particulate,
disperse, and porous system, in which the interfacial
area per unit volume can be very large. The disperse
nature of the soil and its consequent interfacial
activity give rise to such phenomena as adsorption
of water and chemicals, ion exchange, adhesion,
swelling and shrinking, dispersion and flocculation,
and capillarity.

11. Definitions, Daubenmire, Plants and Environment,
1974*
Soil …any part of the earth’s crust in which plants
are anchored: the muddy bottoms of ponds, porous
rock surfaces into which cryptogams send their
rhiziods, peat, raw gravel deposited by glaciers, etc.
Soil may be defined as the weathered superficial
layer of the earth’s crust with which are mingled
living organisms and products of their decay.
*A Textbook of Autecology, 3
rd
ed.

12. Definitions, Spangler & Handy, 1982, Soil Engineering
Soils are natural materials which occur in infinite
variety over the earth and whose engineering
properties may vary widely from place to place
within the relatively small confines of a single
engineering project …
The properties of soils are continuously changing as
the amount of moisture fluctuates and other
environmental influences vary… and may change
dramatically under load
Soil is used as construction material …

13. Definition, Soil Science Glossary, SSSA
(i) The unconsolidated mineral or organic material
on the immediate surface of the earth that serves
as a natural medium for the growth of land plants.

14. Definition, Soil Science Glossary, SSSA, cont’d
(ii) The unconsolidated mineral or organic matter
on the surface of the earth that has been subjected
to and shows effects of genetic and environmental
factors of: climate (including water and
temperature effects), and macro- and
microorganisms, conditioned by relief, acting on
parent material over a period of time. A product-
soil differs from the material from which it is
derived in many physical, chemical, biological,
and morphological properties and characteristics.

15. Definition, Joffe, 1949, modified by Birkeland, 1999
Soil is a natural body consisting of layers
(horizons) of mineral and/or organic constituents
of variable thicknesses, which differ from the
parent materials in their morphological, physical,
chemical, and mineralogical properties and their
biological characteristics.

16. Definition, Soil Taxonomy, 2
nd
ed.
Soil is a natural body comprised of solids
(minerals and organic matter), liquid, and gases
that occurs on the land surface, occupies space,
and is characterized by one or both of the
following: horizons, or layers, that are
distinguishable from the initial material as a result
of additions, losses, transfers, and transformations
of energy and matter or the ability to support
rooted plants in a natural environment.

17. Definition, Soil Taxonomy, 2
nd
ed.
The upper limit of soil is the boundary between
soil and air, shallow water, live plants, or plant
materials that have not begun to decompose. Areas
are not considered to have soil if the surface is
permanently covered by water too deep (typically
more than 2.5 meters) for the growth of rooted
plants.

18. Definition, Soil Taxonomy, 2
nd
ed.
The lower boundary that separates soil from the
nonsoil underneath is most difficult to define. Soil
consists of horizons near the earth's surface that, in
contrast to the underlying parent material, have
been altered by the interactions of climate, relief,
and living organisms over time. Commonly, soil
grades at its lower boundary to hard rock or to
earthy materials virtually devoid of animals, roots,
or other marks of biological activity. For purposes
of classification, the lower boundary of soil is
arbitrarily set at 200 cm.