ANDISOL SPOD 1

8/7/2019 ANDISOL SPOD 1

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SOIL TAXONOMY









SOIL ORDERS

� Five of these orders exist in a wide variety of climates:Entisols, Inceptisols, Histosols, Andisols, and

Vertisols.

� The 6 other Orders are primarily a product of time.

� Worldwide extent:� Aridisols 19%

� Alfisols 13%

� Inceptisols 9%

� Mollisols 8%

� Oxisols 8%� Others 43%

� One-fifth of world¶s surface is mountainous and notclassified





Photo of soil profile

Spodosol

Photos courtesy of USDA NRCS, National Survey Center

http://www.statlab.iastate.edu/soils/photogal/orders/soiord.htm

Andisol



ANDISOL

Andisols are soils developing in parent containing

at least fifty percent volcanic ash. The layers of ash can be seen in this Andisol from Hawaii.

Naturally fertile soils, they support a dense natural

cover in moist climates. Andisols occur around

individual volcanoes created from andesite-richmagma. They are common on the volcanic islands

and mountains of "The Ring of Fire", which ring the

Pacific Ocean.



� Andisols are soils that have formed in volcanicash or other volcanic ejecta. These soils differ from those of other orders in that they typically

are dominated by glass and poorly crystallinecolloidal materials such as allophane, imogolite,and ferrihydrite (andic properties). As a result,

Andisols possess many unique chemical andphysical properties that include high water-holding capacity and the ability to 'fix' (and makeunavailable to plants) large quantities of phosphorus.



Soil Orders - An Orientation -

Andisols:

Andisols are usually weakly developed.

� Used to be Entisols and Inceptisols, but

have special properties and were split off

some years ago.

� They must have enough development to

take them out of Entisols, but not so much

as to remove andic properties.� Usually 5,000 - 10,000 years old.



� Andic properties (must have 35 cm of this in top60 cm of soil):

� 1. Low bulk density

� 2. Potential for wind erosion� 3. Amorphous clays (Fe hydrous oxides)

� 4. High macroporosity and rapid drainage

� 5. Low soil strength.

� This constitutes a melanic epipedon (>6% C intop 30 cm) was defined for these soils.



SUBORDERS

Andisols are divided into 8 suborders: Aquands, Gelands, Cryands,

Torrands, Xerands, Vitrands, Ustands, and Udands.

Soil Orders - An Orientation - Andisols:

Suffix -and:

Aquands: wet

Cryands: very cold

Torrands: hot and dry

Udands: udic (adequate water)

Ustands: ustic (dry winter) moistureVitrands: volcanic glass

Xerands: xeric (dry summer)

Ando, in Japanese means black volcanic



GREAT GROUPS

� AQUANDS ± CRYAQUANDS

± PLACAQUANDS

± DURAQUANDS

± VITRAQUANDS

± MELANAQUANDS ± EPIAQUANDS

± ENDAQUANDS

� CRYANDS ± DURICRYANDS

± HYDROCRYANDS

± MALANOCRYANDS

± FULVICRYANDS

± VITRICRYANDS

± HAPLOCRYANDS

� TORRANDS ± DURITORRANDS

± VITRITORRANDS

± HAPLOTORRANDS

� UDANDS ± PLACUDANDS

± DURIUDANDS

± MANLANUDANDS

± HYDRUDANDS ± FULVUDANDS

± HAPLUDANDS



� USTANDS ± DURUSTANDS

± HAPLUSTANDS

� VITRANDS ± USTIVITRANDS

± UDVITRANDS

� XERANDS ± VITRIXERANDS

± MEALANOXERANDS

± HAPLOXERANDS

GREAT GROUPS



SPODOSOL

� SOILS WITH A SPODIC HORIZON� A SPODIC HORIZON IS AN ILLUVIAL HORIZON ENRICHED

WITH AN ACTIVE MIXTURE OF ORGANIC MATTER ANDALUMINUM WITH OR WITHOUT IRON

� WHEN IT IS CEMENTED IT IS CALLED AN ORTSTEIN

� THERE IS USUALLY AN OVERLYING ALBIC HORIZON� THESE SOILS USED TO BE CALLED PODZOLS

� THEY ARE MOST EXTENSIVE IN COOL OR HUMID REGIONS

� CONDITIONS FAVORING THEIR DEVELOPMENT ARE:

� SANDS RICH IN QUARTZ CONTENT

� HUMID CLIMATES

� INTENSIVE LEACHING

� MOST HAVE FORMED UNDER CONIFERS

� THEY CAN FORM UNDER GRASSES OR HARDWOODS



CHARACTERISTICS

� SPODOSOLS HAVE A HIGH SAND CONTENTTHROUGHOUT THEIR PROFILE.

� HIGH RAINFALL AND EASY LEACHING PRODUCETRANSLOCATION OF HUMUS AND/OR SESQUIOXIDECOLLOIDS INTO A SPODIC B HORIZON.

� SESQUIOXIDES ARE METAL OXIDES. THEY AREMINERALS CONTAINING 1.5 ATOMS OF OXYGEN PER

ATOM OF THE METAL

� PARTICULARLY Fe02 & AL2O3, (SESQUI = 1.5 TIMES)

� SPODOSOLS HAVE MODERATELY TO STRONGLY ACIDIC SANDY PROFILES WITH AN ASHY WHITEUPPER HORIZON OVER A DARK BROWN B HORIZON

AND YELLOWISH SUBSOILS



DEVELOPMENT

� ACCUMULATION OF ORGANIC

MATTER

� LEACHING

& ACIDIFICATION� WEATHERING - CLAY REMOVAL

� TRANSLOCATION OF Fe & Al FROM A

TO B HORIZONS� REDUCTION IN BULK DENSITY

� CEMENTING



SUBORDERS

� Suffix -od

� Aquods: wet

� Cryods: very cold

� Ferrods: high Fe oxide� Humods: high humus

� Orthods: central concept, not one of theothers.

� Migration of chelated Fe and Al from E to Bhshorizon facilitated by organic acids



� Aquods

� Aquods are the wet Spodosols. They arecharacterized by a shallow fluctuating water table.

� The vegetation is water-loving plants, rangingfrom moss, shrubs, and trees in cold areas tomixed forests and palms in the warmest areas.Most Aquods are used as forest or wildlife

habitat.� Aquods are naturally infertile, but they can behighly responsive to good management.



� Cryods

� Cryods are the cold Spodosols of high

latitudes and/or high elevations.� The vegetation is mostly coniferous forest.

� Most Cryods are used as forest or wildlife

habitat.



� Humods

� Humods are the relatively freely drained Spodosols thathave a large accumulation of organic carbon in thespodic horizon.

� Most Humods formed under coniferous forest vegetation.These soils are used mainly as forest.

� Orthods

� Orthods are the relatively freely drained Spodosols thathave a moderate accumulation of organic carbon in thespodic horizon.

� Most Orthods are used as forest or have been clearedand are used as cropland or pasture.

� Orthods are naturally infertile, but they can be highlyresponsive to good management.

� The spodic horizon can be destroyed under cultivation,

particularly if lime and nitrogen are applied.



CHARACTERISTIC OF SUBORDERS

� Aquods - poorly drained Spodosols with a water

table at or near the surface for much of the year

� Gelods - Spodosols of very cold cimates (mean

annual soil temperature <0°C)

� Cryods - Spodosols of cold climates

� Humods - well-drained Spodosols that contain

relatively large quantities of organic matter � O rthods - common Spodosols that don't meet

requirements of other suborders



Great Groups

� AQUODS ± CRYAQUODS

± ALAQUODS

± FRAGIAQUODS

± PLACAQUODS

± DURAQUODS ± EPIAQUODS

± ENDOAQUODS

� CRYODS

± PLACOCRYODS ± DURICRYODS

± HUMICRYODS

± HAPLOCRYODS

� HUMODS ± PLACOHUMODS

± DURIHUMODS

± FRAGIHUMODS

± HAPLOHUMODS

� ORTHODS ± PLACORTHODS

± DURORTHODS

± FRAGIORTHODS

± ALORTHODS

± HAPLORTHODS





Characteristic Profile

� Spodic B horizon: zone of sesquioxide andorganic acid accumulation.

� Moderately to strongly acid soils

� Typical profile ± Oi

± Oe

± Oa (thick)

± E ± Bs, Bh, or Bhs

± other horizons



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ANDISOL SPOD 1