Soil Science Test 2

What Country uses the CLOPRT system?

Russia

What is the World Reference Base for soils called?

FAO-UNESCO

Who started the Classification system?

C.F. Marbut in 1927

Soil Taxonomy

categorizes soils based on soil properties that can be observed and measured, uses terminology that gives a definite understanding of major soil characteristics

How many categories are in soil taxonomy?

order, suborder, great group, subgroup, family, series

How are Diagnostic soil horizons described?

specific and measurable characteristics

Where are epipedons located?

surface horizons (O, A, and upper B)

Mollic

common midwest epidedon, thick dark color layers, high base saturation, moist at least 3 months of the year, under grasslands

Ochric

thin layer, light color, not a lot of organic matter

anthropic

accumulation of phosphate due to human/ animal waste disposal

folistic

organic material at the surface saturated for less than 30 days/yr

histic

organic material at surface saturated more than 30 days/yr

melanic

black material at surface with andic properties

plaggen

man-made by years of manure/soil/vegetation additions, >50 cm thick

umbric

like mollic but base saturation (pH=7), is less than 50%

oxic

highly weathered, leached

Common subsurface in horizons

argillic, calcic, cambic, glossic

argillic

accumulation of silicate clays (Bt)

calcic

secondary accumulation of carbonates, >15% CaCO3 equivalent, > 15cm thick (Bk, Ck,)

cambic

weak indication of pedogenic processes, but little clay or humus accumulation

glossic

whitish eluvial horizon that tongues into a Bt horizon

Soil moisture regime

presence or absences of water in a soil

Aquic

soil is saturated with water and has little or no gaseous oxygen (grey color)

Udic

soil moisture is high enough to meet plant needs most of the year

Aridic

soil dry at least ½ of growing season

xeric

cool, wet winters, and hot, dry summers (Mediterranean Climate)

Frigid

soils with means annual temperature lower than 8 degrees C but higher than 0, difference between mean summer and mean winter soil temperatures greater than 5 degrees C, warm summer temperatures

Cryic

same as frigid but cold summer temperatures

mesic

mean annual temperature above 8 degrees C, but less than 15 degrees C, difference between mean summer and mean winter soil temperature is greater than 5 degrees C

Thermic

mean annual temperature above 15 degrees C but less than 22 degrees C

Nomenclature of Soil Taxonomy

Name of classification units are made up of syllables that convey a specific concept of soil character or genesis

Antigo Series

coarse-loamy over sandy or sandy-skeletal, mixed, super active, frigid Haplic Glassudlafs

Tama Series

Fine-silty, mixed, super active, mesic Typic Argiudolls

Entisols

little to no horizon development, little weathering takes place (recent alluvium, recent lava flows, desert regions, steep slopes, and disturbed areas)

Inceptisol

(-ept) beginning of soil profile, usually has an ochric epipedon, has a cambic subsurface horizon, but no argillic or kandic horizon, (North Carolina and Colorado)

Andisols

(-and), volcanic materials deposited in recent geologic time, not highly weathered, characterized by poorly crystalline minerals (Oregon and Costa Rica)

Gelisols

(-el), permafrost, show some features of cryoturbation, or frost, young soils with little profile development, created problems with construction

Histosols

(-ist), have organic material in more than half of the upper 80cm of soil, have undergone little profile development because of an anaerobic environment, usually found in marshes, bogs, and swamps,

Aridisols

(-id), have an aridic moisture regime, characterized by an ochric epipedon light in color, and low in organic matter, often have an accumulation of soluble salts, calcium carbonate, and gypsum; the main land use is rangeland (New Mexico and Arizona)

Vertisols

(-ert), Characterized by having clays with high shrink-swell capacity, clay-rich soils that shrink and swell with changes in moisture content, >30% clay to a depth of 1m or more, usually found under glassland, (soils are dark, often form large cracks on the surface when dry) (not good for contruction base)

Mollisols

(-Oll), main soil forming process is accumulation of organic matter, developed under grassland vegetation, characterized by a deep, dark A horizon high in base-forming cations, dominant soils of great plans and Midwest agriculture areas (Illinois and Iowa)

Alfisols

(-alf), native forest vegetation, subsurface horizon with clay accumulation, ochric epipedon, greater than 35% base saturation (Wisconsin and Minnesota)

Utisols

(-ult), developed under warm conditions, tropical climates, usually under forest vegetation, highly weathered minerals than alfisols, subsurface usually is red or yellow (Alabama and South Carolina)

Spodosols

(-od), mainly on sandy parent material that leaches easily, intensive acid leaching is main soil forming process, spodic subsurface (Michigan and North Carolina)

Oxisols

(-ox) highly weathered soils, hot climates with year-round moisture, orchic or umbric epipedons, deep, oxic subsurface, (Hawaii)