World Soil Types
World Soil Types
UN (FAO) SOIL SAMPLES.
CODE: 000001
Soil sample set based on the classification set by the World Reference
Base for Soil Resources (UN).
Soils have undergone some processing to enable them to be imported into most
countries. Processing includes: calcination, removal of organic content &
reconstruction: The set should be shipped under HS CODE: 25174900 and not
shipped or classified as soil.
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Acrisol
Andosol
Calcisols
Chernozem
Durisol
Ferralsol
Gypsisol
Nitisol
Phaeozem
Plinthosol – petroplinthite
Solonchak
Vertisol
UN (FAO) CLASSIFICATION SOIL SAMPLES.
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Geology Samples.com
World Soil Types
ACRISOLS (AC): Soils with subsurface accumulation of low activity clays and low base
saturation
ALISOLS (AL): Soils with sub-surface accumulation of high activity clays, rich in
exchangeable aluminum
ANDOSOLS (AN): Young soils formed from volcanic deposits
CHERNOZEMS CH): Soils with a thick, dark topsoil, rich in organic matter with a
calcareous subsoil
FERRALSOLS (FR): Deep, strongly weathered soils with a chemically poor, but
physically stable subsoil
GYPSISOLS (GY): Soils with accumulation of secondary gypsum
NITISOLS (NT): Deep, dark red, brown or yellow clayey soils having a pronounced
shiny, nut-shaped structure
PHAEOZEMS (PH): Soils with a thick, dark topsoil rich in organic matter and evidence
of removal of carbonates
PLINTHOSOLS (PT): Wet soils with an irreversibly hardening mixture of iron, clay and
quartz in the subsoil
SOLONCHAKS (SC): Strongly saline soils
VERTISOLS (VR): Dark-coloured cracking and swelling clays
Introduction
For describing and defining the reference soil groups of the World Reference Base for Soil
Resources, use is made of soil characteristics, properties and horizons which are combined
to define soils and their relationships.
Soil characteristics are single parameters which are observable or measurable in the field or
laboratory, or can be analysed using microscope techniques. They include such
characteristics as colour, texture and structure of the soil, features of biological activity,
arrangement of voids and pedogenic concentrations (mottles, cutans nodules, etc.) as well as
analytical determinations (soil reaction, particle-size distribution, cation exchange capacity,
exchangeable cations, amount and nature of soluble salts, etc.).
Soil properties are combinations ("assemblages") of soil characteristics which are known to
occur in soils and which are considered to be indicative of present or past soil-forming
processes (e.g. vertic properties, which are a combination of heavy texture, smectitic
mineralogy, slickensides, hard consistence when dry, sticky when wet, shrinking when dry
and swelling when wet).
Soil horizons are three-dimensional pedological bodies which are more or less parallel to the
earth's surface. Each horizon contains one or more property, occurring over a certain depth,
which characterizes it. The thickness varies from a few centimetres to several metres; most
commonly it is about a few decimetres. The upper and lower limits ("boundaries") are gradual,
clear or abrupt. Laterally, the extension of a soil horizon varies greatly, from a metre to
several kilometres. However, a soil horizon is never infinite. Laterally, it disappears or grades
into another horizon.
Soils are defined by the vertical combination of horizons, occurring within a defined depth,
and by the lateral organization ("sequence") of the soil horizons, or by the lack of them, at a
scale reflecting the relief or a land unit.
Soils in the sets have been taken from the soil horizon that best displays the identifying
characteristics of the particular soil type.
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World Soil Types
Acrisol
A clay-rich soil generally associated with areas of humid, tropical climates. It is one of the 30
major soil groups of the. The acrisols have low fertility and toxic amounts of aluminium lthat
imit agricultural usage, ithey can however be used for forestry: tea, rubber tree, oil palm
plantations.
PROPERTIES OF ACRISOLS (AC)
Other soils having an argic horizon with a cation exchange capacity (by 1 M NH4OAc) equal
to or more than 24 cmolc kg-1 clay throughout.
Andosol
Andosols (from Japanese an meaning dark and soil) are soils found in volcanic areas formed
in volcanic tephra. In some cases can andosols also be found outside active volcanic areas.
Andosols cover an estimate of 1-2% of earth's ice-free land surface. Poorly developed
Andosols are often rich in vitreous materials and are called Vitric Andosols (see set sample).
Because they are generally quite young, Andisols typically are very fertile except in cases
where phosphorus is easily fixed (this sometimes occurs in the tropics). They can usually
support intensive cropping, with areas used for wet rice in Java supporting some of the
densest populations in the world.
Andisols occupy ~1% of the global ice-free land area.
PROPERTIES OF ANDOSOLS (AN)
Other soils having a spodic horizon starting within 200 cm from the soil surface, underlying an
albic, histic, umbric or ochric horizon, or an anthropedogenic horizon less than 50 cm thick.
Calcisols
A Calcisol is a soil with a substantial secondary accumulation of lime. Calcisols are common
in calcareous parent materials and widespread in arid and semi-arid environments. Formerly
Calcisols were internationally known as Desert soils and Takyrs. Calcisols are developed in
mostly alluvial, colluvial and aeolian deposits of base-rich weathering material. They are
found on level to hilly land in arid and semi-arid regions. The natural vegetation is sparse and
dominated by xerophytic shrubs and trees and/or ephemeral grasses.
Dryness, and in places also stoniness and/or the presence of a shallow petrocalcic horizon,
limit the suitability of Calcisols for agriculture. If irrigated, drained (to prevent salinisation) and
fertilised, Calcisols can be highly productive under a wide variety of crops. Hilly areas with
Calcisols are predominantly used for low volume grazing of cattle, sheep and goats.
Many Calcisols occur together with Solonchaks that are actually salt-affected Calcisols and/or
with other soils with secondary accumulation of lime that do not key out as Calcisols. The total
Calcisol area may well amount to some 10 million square kilometres, nearly all of it in the arid
and semi-arid (sub)tropics of both hemispheres.
PROPERTIES OF CALCISOLS (CL)
Other soils having an argic horizon within 100 cm from the soil surface with an irregular upper
boundary resulting from albeluvic tonguing into the argic horizon.
Chernozem
Chernozem is a black-coloured soil containing a high percentage of organic material: 7% to
15%. High percentage of phosphoric acids, phosphorus and ammonia. Chernozems are very
fertile. There are two "Chernozem belts" in the world: from Northern Serbia, Northern Bulgaria
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World Soil Types
(Danubian Plain) and Southern Romania (Wallachian Plain), to Northeast Ukraine across the
Black Earth Region and Southern Russia into Siberia, and the other in the Canadian Prairies.
Similar soil types occur in Texas and Hungary. It has a large depth, often more than 40 inches
(1 m) and up to 250 inches (6 metres) in Ukraine.
PROPERTIES OF CHERNOZEMS (CH)
Soils having
1. a mollic horizon with a moist chrome of more than 2 to a depth of at least 20 cm, or
having this chrome directly below any plough layer; and
2. concentrations of secondary carbonates within 100 cm from the soil surface; and
3. no diagnostic horizons other than an argic, calcic, cambic, gypsic or vertic horizon.
Durisol
A very shallow to moderately deep, free-draining soil of arid and semi-arid environments, that
contain cemented secondary silica (SiO2) in the upper metre of soil. Durisols are
internationally known as "hardpan soils" (Australia) or "dorbank" (South Africa) or they
represent the "duripan phase" of other soils. Durisols are developed mainly in alluvial and
colluvial deposits of all texture classes. They are found on level and slightly sloping alluvial
plains, terraces and gently sloping piedmont plains in arid, semi-arid and Mediterranean
regions.
Extensive areas of Durisols occur in Australia, in South Africa, Namibia and in the USA
(notably in Nevada, California and Arizona); minor occurrences have been reported from
Central and South America and from Kuwait.
PROPERTIES OF DURISOLS (DU)
Soils having
1. a calcic or petrocalcic horizon within 100 cm of the surface; and
2. no diagnostic horizons other than an ochric or cambic horizon, an argic horizon which
is calcareous, a vertic horizon, or a gypsic horizon underlying a petrocalcic horizon.
Ferralsol
Ferralsols are red and yellow weathered soils whose colours result from an accumulation of
metal oxides, particularly iron and aluminum (from which the name of the soil group is
derived). They are formed on geologically old parent materials in humid tropical climates, with
rainforest vegetation growing in the natural state. Because of the residual metal oxides and
the leaching of mineral nutrients, they have low fertility and require additions of lime and
fertilizer if they are to be used for agriculture.
PROPERTIES OF FERRALSOLS (FR)
Soils having a natric horizon within 100 cm from the soil surface.
Gypsisol
Gypsisols are characterised by a subsurface layer of gypsum (a hydrated calcium sulfate)
accumulated by the precipitation of calcium and sulfate from downward percolating waters in
the soil profile. With intensive management, irrigated crops can be grown on these soils.
Occupying about 0.7 percent of the continental land area on Earth, Gypsisols occur in the
very arid regions of the world (North Africa, the Middle East), sometimes in association with
Calcisols, as in Australia and the United States.
PROPERTIES OF GYPSISOLS (GY)
Soils having a duric or petroduric horizon within 100 cm from the soil surface.
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World Soil Types
Histosol
Histosol is a soil consisting primarily of organic materials. They are defined as having 40
centimetres (16 in) or more of organic soil material in the upper 80 centimetres (31 in).
Organic soil material has an organic carbon content (by weight) of 12 to 18 percent, or more,
depending on the clay content of the soil. These materials include muck (sapric soil material),
mucky peat (hemic soil material), or peat (fibric soil material). Aquic conditions or artificial
drainage are required. Typically, histosols have very low bulk density and are poorly drained
because the organic matter holds water very well. Most are acidic and many are very deficient
in major plant nutrients which are washed away in the consistently moist soil.
Histosols form whenever organic matter forms at a more rapid rate than it is destroyed. This
occurs because of restricted drainage precluding aerobic decomposition, and the remains of
plants and animals remain within the soil. Thus, histosols are very important ecologically
because they, and gelisols, store large quantities of organic carbon. If accumulation continues
for a long enough period, coal forms.
Soils having a histic or folic horizon,
1. either a. 10 cm or more thick from the soil surface to a lithic or paralithic contact;
or b. 40 cm or more thick and starting within 30 cm from the soil surface; and
2. lacking an andic or vitric horizon starting within 30 cm from the soil surface.
PROPERTIES OF HISTOSOLS (HS)
Soils having one or more cryic horizons within 100 cm from the soil surface.
Nitisol
Nitisol occupy approx. 1.6 percent of the total land surface on Earth, Nitisols are found mainly
in East Africa at higher altitudes, coastal India, Central America, and tropical islands (Cuba,
Java, and the Philippines). They are perhaps the most inherently fertile of the tropical soils
because of their high nutrient content and deep, permeable structure. They are exploited
widely for plantation agriculture. Nitisols are technically defined by a significant accumulation
of clay (30 percent or more by mass).
PROPERTIES OF NITISOLS (NT)
Other soils having
1. an argic horizon, which has a cation exchange capacity (by 1 M NH4OAc) of less than
24 cmolc kg-1 clay in some part, either starting within 100 cm from the soil surface, or within
200 cm from the soil
surface if the argic horizon is overlain by loamy sand or coarser
textures throughout, and
2. a base saturation (by 1M NH4OAc) of less than 50 percent in the major part between
25 and 100 cm.
Phaeozem
Phaeozems are characterized by a humus-rich surface layer covered in the natural state with
abundant grass or deciduous forest vegetation. They are highly arable soils and are used for
growing wheat, soybeans, and pasture for cattle, as well as for wood and fuel production.
Occupying about 1.5 percent of the continental land area on Earth, Phaeozems are found
principally in the North American prairies, the South American pampas, and the subtropical
steppes of Asia.
Plinthosol
Plinthosols form under a variety of climatic and topographic conditions. They are defined by a
subsurface layer containing an iron-rich mixture of clay minerals (chiefly kaolinite) and silica
that hardens on exposure into ironstone concretions known as plinthite. The impenetrability of
the hardened plinthite layer, as well as the fluctuating water table that produces it, restrict the
use of these soils to grazing or forestry, although the hardened plinthite has value as
subgrade material for roads or even as iron ...
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World Soil Types
Solonchak
Solonchak is pale or grey soil type found in arid to subhumid, poorly drained conditions. The
word is Russian for "salt marsh" in turn from Russian sol, "salt".
PROPERTIES OF SOLONCHAKS (SC)
Other soils having
1. gleyic properties within 50 cm from the soil surface; and
2. no diagnostic horizons other than a anthraquic, histic, mollic, ochric, takyric, umbric,
andic, calcic, cambic, gypsic, plinthic, salic, sulfuric or vitric horizon within 100 cm from the
soil surface.
Vertisol
Vertisol is a soil in which there is a high content of expansive clay known as montmorillonite
that forms deep cracks in drier seasons or years. Alternate shrinking and swelling causes
self-mulching, where the soil material consistently mixes itself, causing vertisols to have an
extremely deep A horizon and no B horizon. (A soil with no B horizon is called an A/C soil).
This heaving of the underlying material to the surface often creates microrelief known as
gilgai.
Vertisols typically form from highly basic rocks such as basalt in climates that are seasonally
humid or subject to erratic droughts and floods, or to impeded drainage. Depending on the
parent material and the climate, they can range from grey or red to the more familiar deep
black (known as black earths in Australia, and black cotton soils in East Africa).
Vertisols are found between 50° N and 45° S of the equator. Major areas where vertisols
are dominant are eastern Australia (especially inland Queensland and New South Wales), the
Deccan Plateau of India, and parts of southern Sudan, Ethiopia, Kenya, and Chad (the
Gezira), and the lower Parana River in South America. Other areas where vertisols are
dominant include southern Texas and adjacent Mexico, northeast Nigeria, Thrace, and parts
of eastern China.
The natural vegetation of vertisols is grassland, savanna, or grassy woodland. The heavy
texture and unstable behaviour of the soil makes it difficult for many tree species to grow, and
forest is uncommon.
The shrinking and swelling of vertisols can damage buildings and roads, leading to extensive
subsidence. Vertisols are generally used for grazing of cattle or sheep. It is not unknown for
livestock to be injured through falling into cracks in dry periods. Conversely, many wild and
domestic ungulates do not like to move on this soil when inundated. However, the shrinkswell activity allows rapid recovery from compaction.
PROPERTIES OF VERTISOLS (VR)
Other soils having
1. fluvic soil material starting within 25 cm from the soil surface and continuing to a
depth of at least 50 cm from the soil surface; and
2. no diagnostic horizons other than a histic, mollic, ochric, takyric, umbric, yermic, salic
or sulfuric horizon.
World Soil Types
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