Parent rock changes to ______ ________ by physical and chemical weathering.
1)_______ weathering dominates over _________weathering in the temperate regions of the world
2)_______ weathering dominates over _________weathering in the tropics.
1) Physical over chemical in temperate
2)Chemical over physical in tropics
2 Dominate effects of physical waethering over chemical weathering
1) decreases ion particle size
2) increases surface area
When parent rock weathers secondary minerals are formed, which become the _____ fraction in soils
Name 5 elements which are formed from the chemical weathering process from parent rock to parent material which are made available to plants...Why are they available? What is the danger of these elements in the tropics?
Chemical weathering produces Si, Na, K, Ca,Mn, Fe, Al and Mg. They are available because the chemical weathering process makes these elements soluable. Under certain conditions in the tropics these elements can become toxic ie Al toxicity
WHAT ARE THE 4 SOIL FORMING Processes? Define each.
Additions-Inputs of materials into developing soils. Organic matter and dust. Also manure and ferts.
Losses-Meterials are lost from the soil profile through leaching to groundwater, erosion of the surface materials, or other forms of removal. Environmental factors
Translocation-Involve the movement of organic and inorganic materials laterally within the horizon or vertically from one horizon to the other. Water either percolating down with gravity or rising p through capilary action is the most common translocation agent.
Transformation-occur when soil constituents are chemically or physically modified. As primary minerals decompose, the decomposition products recombine into new materials that include additional types of silicate clays and hydrous oxides of Fe and Al.
Name the 5 factors influencing soil formation and describe.
Parent materials-geological or organic precursors to the soil
Climate-primarily percipitation and temp
Biota- living organisms, especially native vegetation, microbs, soil animals, and humans
Topography- Slope, aspect, landscape position
Time-the period of time since the parent material began to undergo soil formation.
debris made up of poorly sorted rock fragments detached from the heights above and carried downslope, mostly by gravity, assisted in some cases by frost action.
Describe an A horizon
the layers nearest the surface that are dominated by mineral particles but have been darked from the accumulation of organic matter.
Describe a O horizon
Only in undisturbed ecosystems like forests have a top layer of soil which consists of fallen leaves, plant and animal remains. These materials go through chemical and physical breakdowns and transformations. Older layers of this material, after no noticable plant structure is seen, make up the O horizon
Describe an E horizon
Intensely weathered and leached horizons that have not accumulated organic matter. usually just below the A horizon
Describe the B horizon
Underlaying layer where silicate clays, iron and aluminum oxides, gypsum, or calcium cabonate may accumulate. The accumulated materials have been washed down from above or are formed with in the B horizon.
Describe a C horizon
The least weathered horizon usually on bottom. Contains parent rock material.
Zone of accumulation of minerals and clays. HAPPENS IN B HORIZON
Zones of maximum leaching of clays , iron, and aluminum oxides. these zones are lighter in color. Rarely found in grasslands.
When discussing Moisture regimes, define Aquic.
Soil that is saturated with water and virtually free of gaseous oxygen for sufficient periods of time.
When discussing soil moisture regimes, define udic and perudic.
Udic-Soil moisture is high year round. Common in humid climates and make up 1/3 of soils worldwide.
Perudic-extremely wet moisture regime with excess moisture that causes heavy leaching throughout the year.
Whan discussing Moisture Regimes, define Ustic.
Soil moisture intermediate,adiquate moisture for growth but signifigant periods of drought.
When discussing Moisture regimes, define aridic and torric.
aridic-Moist less than 90 days of the year. Usually in arid regions. very dry, not neccessarily hot.
torric-Same as aridic but is hot and dry in summer.
What are the three primary minerals found in Basalt? Which one is the pyroxene?
What are the 3 primary minerals found in Granite?
Course weathered material in high in ________?
Fine weathered material is high in ________ and _______?
2) Fe and Mg
Name the 5 lightly colored primary minerals listed in Deeniks graph.
Name the 5 secondary light colored minerals listed in Deeniks graph.
Name the three dark colored primary minerals listed in Deeniks graph.
These soils are usually associated with deciduous forests, are mildly acidic, and have a moderate to high fertility.
This subsurface horizon is characterized by silicate clay accumulation with
This subsurface horizon is an accumulation of high-activity silicate clays.
Epipedons refer to the _________ horizons of soils.
Place these temperature regimes in order from hottest to coldest: mesic, thermic, frigid, hyperthermic, cryic
hyperthermic, thermic, mesic, frigid, cryic
Place these moisture regimes in order from most wet to dryest: xeric, udic, torric, perudic, ustic
perudic, udic, ustic, xeric, torric
If a soil is described as "active" this refers to what?
High cation exchange capacity (fertile)
Each of these soils is usually associated with a specific environment:
a) Spodosols _____________
a) cool, wet coniferous forests
c) tropical rainforests
As temperature increases (as in tropical climates), chemical weathering _______________
increases or is accelerated
As precipitation increases, clay content generally _________
As precipitation increases, pH generally ___________
Decreases (higher acidity)
As precipitation increases, CO3 content _____________
As precipitation increases, oxide content ___________.
These soils are found ONLY in tropical environments.
Sesquic clays are high in __________________
Fe and Al Oxides
Under the absence of oxygen (such as in saturated soils) Iron will undergo ___________ instead of oxidization.
What are the two most common secondary minerals in clays?
Montmorillonite and Kaolinite
Another rule of thumb...Do light or dark rocks weather faster and produce more fertile soils.
A good rule of thumb, finely-textured rocks weather into ________ soils.
The leaching of soil material from an upper horizon to lower horizon is _____________. The site that recieves this material is a site of ____________.
An imaginary 3D version of the soil profile is called the ____________
Unless abused, soils are comprised of four basic components, name them.
Minerals, OM, Air, Water
True or False: Soils are a renewable resource.
Which soil forming factor plays a major role in the huuuuuuge diversity of soils in Hawaii?
Soils serve many different functions, name three.
Medium for growth, recycling system, habitat for organisms, system for water supply and purification, a modifier of the atmosphere, engineering medium
This subsurface horizon is characterized by the accumulation of Al and/or Fe oxide clays.
This type of physical weathering is a result of extreme temperature fluxuations in a short period of time, usually from day to night. The outer layer of rock shrinks and swells at a greater rate than the core of the rock. Usually occurs in desert climates.
This type of Igneous rock has cooled rapidly at the earth's surface, formed small crystals, is usually amorphous, and one resultant rock is Basalt.
This type of Igneous rock cooled slowly over years, produces large crystals, and one resultant rock is Granite.
This type of rock has been cemented or consolidated from physically weathered products of old rocks.
These are rocks that have changed in form from other rocks as a result of extereme heat and/or pressure.
In general, soils derived from basalt will be high in ____________(clay, silt, or sand)
This type of sediment's mode of transport is gravity and usually consists of coarse, stony material mixed with fine material.
Name the 6 dark colored secondary minerals listed in Deeniks graph.
fridged cold winters... thaws in spring or summer
cold season 8-15 degrees C
15-22 degress C mean annual temp
mean annual temp >22 degrees C
tropical warm all year
Ent – recent.Weakly developed mineral soils without natural genetic subsurface horizons. They usually have only an A and C horizon; the A horizon is related to influence of organic matter from vegetation. These are young soils.
Soils with minimal ABC horizon development. The beginning inception of profile development is evident. Often occur on steep slopes.
Soils formed from volcanic ash parent material. They are characterized by low bulk density, high water holding capacity (sometimes greater than 100%), and when weathered they have very high P fixation capacity. Their mineralogy is dominated by amorphous materials (i.e. allophane).
gel - cold young soils with permafrost.
Hist – tissue. Organic soils with little profile development. Contain organic materials in more than half of the upper 80 cm of soil. Characterized by low bulk density and high water holding capacity.
arid – dry. Desert soils or soils characterized by water deficiency through most of the year
Vert – invert. Soils that shrink and swell (churn). High in montmorillonite. Crack when dry and swell close when wet cause
Mollis – soft. Rich soils with high organic matter content in the surface horizon (mollic epipedon) developed from grasslands. High humus content with high CEC and high base saturation. They cover more area in the continental U.S. than any other soil order.
Soils with argillic horizon (high-activity clay accumulation in the B horizon) with high base saturation and slightly acid. They are moderately leached soils.
Highly weathered soils with argillic horizon characterized by very low base saturation (<35%) and low pH.
Spodos – wood ash, grey color. Highly weathered soils of coniferous forests. Have an albic horizon (white because clay minerals leached out) overlying a spodic horizon characterized by accumulation of colloidal organic matter and precipitated Al and Fe oxides. Infertile soils.
Highly weathered soils of the humid tropics. Rich in Al and Fe oxides and characterized by low pH and low fertility. They have a deep oxic B horizon.
what is a soil order
describes main characterisitics of the soil type
what does the sub order describe?
moisture regime, temp regime, diagnostic horizons
what does a great group describe?
3 parts, adds info about horizons
what does a sub group describe?
determines if the central concept of soil order is dominant or not (two words)
what does a soil family decribe?
physical properties such as texture and chemical and clay mineralogy
Names the weathering products of
Olivine, pyroxine, biotite
Clay minerals and iron oxides
Weathering products of feldspar
Clay minerals and Ca, K, Na ions
water born movement
high percipitation = ______ weathering = _____ soils
high percip = high weathering =acidic soils
What effect does temp have on soil formation?
speeds up organic and inorganic reactions when hotter, also breaks up rock due to exfoliation(shrinking swelling of rocks in hot/cold) (physical weathering)
One example of vegetation effecting soil formation
organic acids produced by lichens/mosses
Good drainage = _______ weathering
What effect does aspect have on soil formation
where the soil is facing (ex. northwest) difference in heating and precip
Name the 5 factors of soil formation
know it bitches
what is solum and where is it located
most weathered part of the soil, all horizons but C
what is regolith
is the whole soil horizon from top to bottom (bedrock)
define soil texture
proportion of particles in different size ranges (silt, clay, sand)
define soil structure
How the particles are arranged/configured.
soft friable weathered bedrock retains structure of rock but is porous. C horizon.
Soil Sciences UHM Exam 1
Deenik soil sciences university of hawaii manoa study guide