Global soils
Muska C ornelia
S ummary
introduction of soils
 the nature of the soil
 soil color and texture
 types of soils
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Introduction
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S oil is a combination of weathered rocks, sand, and decomposed
organisms. Different types include sand, silt, clay, or loams.
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S oil can vary greatly from continent to continent, region to region,
field to field  it is influenced by factors and processes that can
vary widely from place to place

http://www.youtube.com/watch?v=Hy_P qKsv9mY
the nature of the soil

vegetation, climate, and time are
important factors in soil
development

a complex mixture of solids,
liquids, and gases.found in soils

soils evolve over long periods of
time from bedrock material

horizons
◦ A horizon contains lots of
organic matter
◦ B horizon is generally rich in
clay
◦ C horizon contains partially
weathered bedrock
soil color and texture
Different locations around the world have different
climates and topographies and support different kinds
of organism, soil types vary in
color: is determined by soil-forming processes and
varies widely.
texture : refers tot he proportions of sand, silt and
clay found in a soil.
mineral composition
◦ P rimary minerals: are minerals that remain from unaltered rock
◦ S econdary minerals: are formed by mineral alternation. -> Clay
minerals and sesquioxides
types of soil
G roup I
soils with well-developed horizons or with fully weathered minerals
Oxisols
Ultisols
Vertisols
S podosols
Mollisols
Aridisols
G roup II
soils with a large proportion of organic matter.
histosols
G roup III
soils with poorly developed horizons or no horizons
E ntisols
Inceptisols
Andisols
Alfisols
Oxisols – Group I
◦ the native vegetation is ra info re s t
– the wet-dry tropical climate
◦ found in the humid climates of
A fric a and S o u t h A m e ric a
◦ the t ro p ic a l s o ils are deep, lack
developed horizons, and are
y e llo w or re d
◦ d a rk coloring indicates a soil is rich
in h u m u s , y e llo w and re d
suggest the presence of iro n and
a lu m inu m
Oxisols – Group I
Ultisols – Group I
◦ S oils of equatorial, tro p ic a l, and
s u b tro p ic a l latitude z o ne s , with
a subsurface horizon of c la y
accumulation and lo w b a s e
s ta tu s
◦ Ultisols are widespread throughout
s o u th e a s t A s ia and E a s t
Ind ie s
◦ Also in e a s te rn A u s tra lia ,
C e ntra l A m e ric a , S o u th
A m e ric a and the s o u th e a s te rn
U nite d S ta te s
Ultisols – Group I
Vertisols – Group I
◦ soil of s u b t ro p ic a l and t ro p ic a l
z o ne s with high clay content and
high base status
◦ Vertisols develop d e e p , wide
cracks when d ry , and the soil
blocks formed by cracking move
with respect to each other
◦ Vertisols typically fo rm u nd e r
g ra s s and savanna vegetation in
s u b t ro p ic a l a nd t ro p ic a l
c lim a t e s with a pronounced d ry
s e a s on
◦ an important region is the Deccan
P lateau of w e s t e rn Ind ia
◦ Vertisols are high in base status
and rich in such nutrient bases as
c a lc iu m and m a g ne s iu m
Vertisols – Group I
Alfisols – Group I
◦ are found in cool to h o t h u m id
a re a s
◦ they are formed mostly u nd e r
fo re s t v e g e ta tio n, but also
u nd e r g ra s s s a v a nna
◦ fertile soil: The principal agricultural
crops grown on Alfisols are c o rn
(m a iz e ), w h e a t, a nd w ine
g ra p e s .
◦ are found in the Mis s is s ip p i and
O hio R iv e r valleys in the U S A ,
through C e ntra l a nd N o rth e rn
E u ro p e into R u s s ia , and in the
S o u th -c e ntra l re g io n o f S o u th
A m e ric a
Alfisols - Group I
S podosols – Group I

Spodisols have a
light-colored horizon
of eluviation and a
dense horizon of
illuvation

develop under cold
needleleaf forests

Canada, Russia
S podosols – Group I
Mollisols – Group I
◦ Mo llis o ls (from Latin mollis,
"soft") are the soils of grassland
ecosystems
◦ they are characterized by a th ic k ,
d a rk s u rfa c e h o riz o n
◦ Mollisols are among some of the
most important and productive
a g ric u ltu ra l soils in the world
and are extensively used for this
purpose
◦ they are found primarily in
subhumid to semiarid grasslands
in E u ro p e , A s ia , th e
A rg e ntine P a m p a , th e G re a t
P la ins o f N o rth A m e ric a , a nd
th e P a lo u s e re g io n o f th e
no rth w e s te rn U nite d S ta te s
Mollisols – Group I
Aridisols – Group I
◦ soils of a rid c lim a te s
◦ are used mainly for ra ng e ,
w ildlife , a nd
re c re a tion
◦ of the dry climate in which
they are found, they are
not us e d for
a g ric ultura l
produc tion unless
irrigation water is available
Aridisols – Group I
Histosols – Group II
◦ are soils that are composed
mainly of o rg a nic m a te ria ls
◦ as a result, Histosols are
e c o lo g ic a lly important
because of the large quantities
of c a rb o n they contain
◦ after d ra ina g e fo r
a g ric ultura l use (particularly
vegetable crops and
cranberries)
Histosols – Group II
E ntisols – Group III
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

most are basically unaltered
from their parent material,
which can be unconsolidated
sediment or rock
entisols are the second most
abundant soil order (after
iinceptitols), occupying about
16% of the global ice-free land
area
in Australia, most entisols are
known as rudosols or tenosols,
whilst arents are known as
anthroposols
E ntisols – Group III
Inceptisols – Group IIII
◦ Inceptisols are soils just starting to
show horizon development because
the s o il is q u ite y o u ng
◦ Inceptisols, like E ntisols, are found in
any type of e nv iro nm e nt and are
commonly found forming in alluvium
on floodplains and delta deposits
◦ for example, they occur in the
Mis s is s ip p i v a lle y , c e ntra l
E u ro p e , th e A m a z o n re g io n,
no rth e a s te rn Ind ia , Ind o ne s ia ,
a nd A la s k a
◦ they are usually arable with
appropriate control of erosion or
drainage
Inceptisols – Group III
Andisols – Group III
◦ soils whose parent
materials are of re c e nt
v olc a nic orig in
◦ They contain much fine
volcanic ash (glass)
◦ The name comes from
andesite, a rock of volcanic
origin.
◦ There are none in South
Carolina.
Andisols – Group III
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