lab exam 1 Flashcards
(57 cards)
Soils are not (a) but (a) can develop into soil. Unlike it, a soil forms at (b) earth surface (c).
(d) includes (e) of the parent material (rocks and minerals) particles (f), (g) the mineral particles, (g) organic matter, (g) the composition and structure of minerals (including clay formation) through (h), and the (i) of soil horizons.
Individual soil is characterized by a unique (j). A (j) is a vertical section (cross section) of the soil exposing all of its horizons. Soil development or (k) is a (l) but slow process.
A (m) is a layer of soil or soil material approximately parallel to the land surface and differing from adjacent horizons in physical, chemical, and biological properties.
Five soil forming factors - (n) influence the type of soil that develops.
a. rock
b. normal
c. temperature and pressure
d. Soil development
e. reducing the size
f. physical weathering)
g. rearranging, adding, changing
h. chemical weathering
i. formation
j. soil profile
k. soil genesis
l. continuous
m. soil horizon
n. climate, living organism, relief, parent material, and time (CLORPT)
(a) do not have to be rock. Soil may develop from materials transported by (b). A geologic map may show different parent materials in an area. Soil properties such as (c) will depend on the kind of parent material that will transform into soil. Soil parent material can either be (d).
Parent material is called (e) if soil developed directly from the (f). Some common (f) in the Philippines include (g).
(h) are divided into (i) based on the method of transportation.
a. Parent materials
b. wind, gravity, water or ice
c. texture, base saturation, including dominant clay minerals
d. residual or transported
e. residual
f. bedrock
g. basalt, andesite, and different types of metamorphic and sedimentary rocks
h. Transported materials
i. four groups
Parent material deposited by (a) is called (b). Alluvial soil can have many (c). Alluvial deposits that occur where the (d) over them are called (e). The soils in the flood plains of (f) are very important for agriculture in the country. They are used extensively for growing rice and other major agricultural crops.
(g) can also be an effective transporter of parent materials. The most common wind transported parent material associated with soils in the country are those (h) ejected during major volcanic eruptions.
Materials deposited at the (i) are called (j). This material is brought down slope by (k).
Sediments transported by (l) are generally referred to as (m). Glacier deposited parent material does not exist in the Philippines. Glacial Drift is important in almost all temperate countries experiencing (n).
a. moving water
b. alluvium
c. different strata of water deposits
d. stream frequently floods
e. flood plains
f. Luzon
g. Wind
h. volcanic ash
i. foot of a steep slope
j. colluvium
k. gravity
l. ice
m. Glacial Drift
n. glaciation
(a) has two major components for soil formation. The first is (b). As the (c), the (d) in the soil will be faster. For (e) in temperature, the (f). (g) will weather faster because the chemical reactions will take place faster and the reactions will occur throughout the year.
Along with temperature is the climate factor of (h). In general, areas with (i). However, the amount of (j) has to be accounted for. Areas that are (k) compared to areas that are (l) back into the atmosphere before leaching can occur. (m) occurs when water moves through the soil and removes the soluble constituents. The leaching zone is determined by the (n) in the soil profile. This is easy to locate because calcium carbonate reacts with (o) or the soil bubbles when acid is applied.
a. Climate
b. temperature
c. mean annual soil temperature increases
d. weathering of rocks and minerals
e. every 10°C rise
f. rate of biochemical reactions doubles
g. Tropical soils
h. precipitation or rainfall
i. more rainfall will have greater weathering and greater leaching
j. evapotranspiration
k. cool and wet will have more leaching
l. hot and wet because more of the rainfall in a hot, wet climate evaporates
m. Leaching
n. location of CaCOs
o. hydrochloric acid to give off carbon dioxide
The organisms living in and on the soil respond to the (a). So biotic factors and climatic factors are interrelated. Animals living in the soil can influence the soil development by their (b). The mixing of the soil by organisms is called (c).
In the Philippines observed differences among soils as affected by (d) are those between grassland and forest areas. For (e), soil develops a (f). Soil developing under (g) will have a (h).
In summary, climate affects the amount of (i) that takes place in the soil and the (j) with which soil horizons develop. Vegetation affects the (k) horizons.
a. climate of the area
b. mixing activities
c. bioturbation
d. vegetation
e. forested areas like diptherocarp forest,
f. thin surface horizon, a leached, light colored zone below the surface, and an accumulation zone that is often brown or red color
g. grassland
h. thick, black surface horizon, a result of thick grassland roots contributing large amounts of organic matter to the surface soil, making it black
i. leaching
j. speed
k. thickness and color of the surface
(a) as a soil-forming factor is related to the soil’s position in the landscape. (a) refers to the (b) of the land surface. Some soils occur on the summit of a hill, some on the backslope, and some on the footslope. The (c) will have a great deal to do with the soil (d).
Slope Profile: 5
In general soils at the (e) develop horizons the fastest.
Soils on the (f) develop slower because (g).
At the (h) position the soils will collect sediment from upslope that can bury the horizons and (i) their development.
Another complicating factor is the (j). Soils with (k) but as the (l). Soil with poor drainage will show (m). For very poorly drained soils the (n) in color. This condition implies that most of the (o).
a. Topography
b. shape or contour
c. position of the slope
d. characteristics
Slope Profile:
- Summit
- Shoulder
- Backslope
- Footslope
- Toe slope
e. summit and shoulder
f. backslope
g. rainfall will run off this slope position faster, there will be more soil erosion, and there will be less leaching
h. footslope
i. slow down
j. depth of the water table in relation to slope position
k. deep water table are considered well drained
l. water table goes up closer to the soil surface drainage becomes poor to very poor
m. redoximorphic features and are reflected in the soil as splotches of red or gray color and are called mottles
n. entire soil below the dark surface will be gray
o. iron has been reduced due to the low O₂ levels
The (a) of a soil is generally considered to be the (b), thus enabling the soil development to proceed. The length of time for a soil to form depends on (c).
In general the age of a soil is not considered in years but (d). Thus young soils have (e) while old soils have (f).
Conditions that hasten the rate of soil development are: 4
Conditions that retard soil development are: 4
How many years does it take for a soil to form? Soil scientists have measured the age of many soils and have a wide range of rates of soil formation. A one-meter thick soil developed from loess in temperate country in 8,000 years, while a one-meter thick soil in tropical country took 75,000 years to form.
In general the following happens with time for a soil: 5
a. age
b. length of time in years since the land surface became stable
c. the intensity of the other active soil forming factors of climate and organisms, and how topography and parent material modify their effect
d. how much development the soil has undergone
e. minimal soil development and few horizons
f. well-developed horizons
Conditions that hasten the rate of soil development are:
- permeable, unconsolidated, parent material,
- warm, humid, climate,
- forest vegetation,
- summit or backslope landscape position that is well drained.
Conditions that retard soil development are:
- Impermeable, hard, consolidated, parent material,
- cold, dry, climate,
- grassland vegetation
- steeply sloping backslopes or shoulders.
In general the following happens with time for a soil:
- thicker horizons that sink deeper into the parent material
- increased iron accumulation making the soils redder
- increased clay content
- increased acidity (soils with lower pH)
- leaching of nutrients so soils are less fertile.
Table 1. Descriptive Soil Profile Symbols.
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OAEBCR
O - Horizon dominated by organic matter.
A- Organic-rich, mineral horizon at or adjacent to the surface.
E - Mineral horizon of maximum eluviation.
B - Mineral horizon of maximum illuviation and formed beneath an O, A, or E horizon.
C - Weathered parent material.
R - Underlying consolidated bedrock.
Table 2. Recognized transitional horizons.
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AB BA AC EB BE BC
AB - A horizon transitional between A and B, dominated by properties characteristic of an overlying A horizon.
BA - A horizon transitional between A and B, dominated by properties characteristic of an overlying B horizon.
AC - A horizon transitional between A and C, dominated by properties characteristic of an overlying A horizon. Common in soils lacking a B horizon.
EB - A horizon transitional between E and B, dominated by properties characteristic of an overlying E horizon.
BE - A horizon transitional between E and B, dominated by properties characteristic of an underlying B horizon.
BC - A horizon transitional between B and C, dominated by properties characteristic of an overlying B horizon.
Table 3. Additional symbols used in combination with the previously described horizon designations. These give more detailed information about the composition of a soil horizon.
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a b c e f g h i k m n o p q r s t v w x y z
a - Organic material which is highly decomposed.
b - A buried soil layer.
c - Concretions cemented by materials harder than lime.
e - Organic material at a transitional stage of decomposition.
f - Frozen ground.
g - A waterlogged (gleyed) layer.
h - An accumulation of illuvial humus.
i - Slightly decomposed organic matter.
k - An accumulation of calcium carbonate.
m - An indurated layer, or hardpan, due to silication or calcification.
n - Accumulation of sodium as an exchangeable ion.
o - Accumulation of residual sesquioxides.
p - A layer disturbed by plowing.
q - Accumulation of silica.
r - Weathered bedrock.
s - An accumulation of illuvial iron.
t - An accumulation of illuvial clay.
v - Plinthite.
w - Color development where illuvial material is absent.
x - A fragipan.
y - An accumulation of gypsum.
z - An accumulation of soluble salts.
An individual soil is characterized by a unique (a). A (a) is a vertical section (cross section) of the soil exposing all of its horizons. Soil development or (b) is a (c) process.
A (d) is a layer of soil or soil material approximately parallel to the land surface and differing from adjacent horizons in physical, chemical, and biological properties.
The parent material is made up of (e).
A (f) consists of a (g), while a (h) is an (j).
The influence of the (i) is quite evident in young soils and becomes blurred by time. (k) are likely to reflect the properties of the rocks and minerals from which they were derived.
a. soil profile
b. soil genesis
c. continuous but slow
d. soil horizon
e. partly weathered rocks and minerals
f. mineral
g. chemical combination of elements
h. rock
j. aggregate of minerals
i. mineral composition of parent materials
k. “Young” soils
There are three major classes of rocks. These are the (a).
Igneous rocks are formed from (b) which, upon cooling crystallized into combinations of various primary minerals. They are the most abundant class of rocks in the (c).
Sedimentary rocks are derived from (d). This group of rocks is the most abundant on the (e).
Metamorphic rocks (f). The transformation process occurred while (g).
a. “Young” soils
b. molten magma
c. earth’s crust
d. earlier generation of rocks that have been subjected to the geological processes of weathering, transportation, and deposition
e. earth’s surface
f. originated from geochemical alteration of igneous and sedimentary rocks
g. in solid state, by heat, pressure and chemically active fluids
(a): a soil layer parallel to the earth’s surface. (a) are exposed in (b). Horizons are distinguished on the basis of their (c) properties. Examples of distinguishing properties: 12
a. Soil horizon
b. soil profiles
c. physical, chemical, and biological
Examples of distinguishing properties:
- depth
- texture
- structure
- PH
- color
- consistency (degree of cohesion)
- boundary between horizons (abrupt, wavy, diffuse, irregular)
- presence of mottles (spots or blotches of different color and size interspersed with the regular color)
- concretions (grains or pellets that are cemented often by calcium carbonate or iron oxide)
- iron content
- organic matter content
- cation exchange capacity
One capital letter is used to designate (a) and two are used for (b). Lowercase subscripts are used to (c) and to designate (d). Master horizons with (e) keep the (f); for example A1, A2, Bt1, Bt2.
The ability to correctly name soil horizons requires that the person be (g). The detective part requires that the person uses all the (h) to correctly determine the (i). Then the person puts all the clues together to make their interpretation of what they are seeing.
Not all soil scientists will write the exact same soil profile description, because their previous experiences will have been different, just like all artists will not paint the same picture when looking at the same landscape scene. However, you will see very similar descriptions, that could be duplicated by another scientist.
As you start gaining experience with naming the horizons for soil profiles, you will become more adept at correctly using all of the clues to write a correct (j)
a. master horizons (A, B, C)
b. transitional horizons (AB, BC)
c. subdivide master and transitional horizons (Bt, Ap)
d. important horizon properties
e. two or more subordinate horizons
f. identical letter identification and are numbered consecutively
g. part “detective” and part “artist”
h. soil morphological clues (color, texture, structure, etc.)
i. influence of the soil forming factors and the pedogenic process that have acted on the parent material
j. “Soil Profile Description.”
Surface soil horizons are mainly influenced by the addition of (a). The (a) that is added to a soil will first be undecomposed. Gradually (b) in the soil will begin to decompose the litter until the original material is no longer recognizable. Eventually the organic matter is converted into (c).
a. organic matter
b. organisms
c. humus so it becomes colloidal in size and it coats the mineral particles of the soil
(a) are all organic matter and are mainly found in (b) where the yearly addition of leaves builds up a layer of undecomposed leaves. In fact, the (a) contains very (c).
The (d), would be mainly undecomposed plant parts. The (e) would be of moderate decomposition, and the (f) would be almost completely decomposed.
Besides being in the leaf litter of forested soils, (a) can also be found in the (g).
a. O-horizons
b. forest soils
c. little mineral soil
d. i subscript, or Oi horizons
e. Oe horizon
f. Oa horizon
g. peat bogs of swamps and wetlands
The (a) is a mineral horizon that is (b) due to the incorporation of decomposed organic matter, which (c). In general, the (d). Soils that developed under grassland will have (e) organic matter in the A horizon for a depth of (f). When an A horizon is plowed, it is called an (g).
a. A horizon
b. dark in color
c. coats the mineral soil particles with colloidal size organic matter
d. darker the mineral soil, the greater the percent organic matter.
e. 4 to 5%
f. 25 cm or more
g. Ap horizon
The (a) is a transition horizon that has characteristics like the A and B, but more like the A; thus, it is called an (a).
(b) develop due to (c). These are zones of (d) or changes in the parent material where (e).
a. AB horizon
b. Subsurface horizons
c. translocation, transformations and losses
d. accumulations
e. color or structure develop
The (a) develops when materials are (b) out of a zone in the soil. The effect of this is to remove the (c) out of this zone, which causes it to be (d) than the horizons above or below it. (a) are found mainly in (e). This horizon is called a (f). Not all soils have (a).
a. E horizon
b. eluviated
c. organic matter and iron
d. lighter in color
e. forested soils
f. zone of eluviation
Below the E horizon or A horizons, there are (a). These are called (b). This kind of B horizon is called a (c), and is a zone of (d) that moved from overlying horizons.
In some (e) where there is not very much clay, the significant translocation of (f) takes place very rapidly. Often the vegetation is an (g) that contributes a very acid O layer. Heavy leaching accompanying the movement of organic acid induced E horizon development. The development of (h) is often accompanied by the development of the (i). The (i) is often (j) in color and easily recognized in the field.
Another example of a B horizon is where the soil has a (k) of illuviation. However, the soil undergoes significant transformations and develops (l) or parent material. This is called a (m).
The (m) does not have enough (n), but is different from the parent material. The (o) is a zone of accumulation, but instead of clay, (p) is accumulating - k. (p) can be identified in a soil profile because it is very (q) and reacts with a (r) as a gas or the soil “bubbles”. The parent material for this soil is high in (p).
The solum describes all horizons (s).
a. zones of illuviation or accumulations
b. B horizons
c. Bt
d. illuviation of clay particles
e. acid sandy soils
f. iron, humus and aluminum
g. evergreen forest
h. E horizon
i. zone of illuviation which is labeled as Bhs horizon (h for humus and s for iron and aluminum)
j. dark red
k. minimal amount
l. different color and structure from the C horizon
m. Bw horizon
n. clay accumulation to be a Bl
o. Bk horizon
p. calcium carbonate (CaCO3)
q. light in color
r. 10% solution of HCI to give off CO2
s. above C horizon (or the zone of pedogenic activity)
(a) are outside the zone of (b). (a) are little altered by the soil forming processes. (a) are referred to as the (c) of the soil.
Soil scientists use their scientific knowledge of the soil and their grasp of soil forming factors to “describe” the soil in the field. There is considerable “art” in describing soils or the interpretation of all the facts to arrive at a depiction of the soil. Artists over the years have used their visual skills to “depict” the soil.
a. C horizons
b. “pedogenesis” (soil development)
c. parent material
Typical horizon characteristics:
O HORIZON
A HORIZON
E HORIZON
B HORIZON
C HORIZON
R HORIZON
O HORIZON Surface litter - fallen leaves and partially decomposed organic debris
A HORIZON Topsoil - organic matter (humus), living organisms. inorganic minerais
E HORIZON Zone of leaching - dissolved or suspended materials move downward
B HORIZON Subsoil - accumulation of iron, aluminum, humic compounds, and clay leached down from the A and E horizons
C HORIZON Weathered parent material - partially broken-down inorganic minerals
R HORIZON Bedrock - Impenetrable layer
(a) are identified by several types of analysis (b) that require special instruments. They can also be identified by a careful study of their (c) which does not use special equipment. These properties include:
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TGCFA OQTCD
a. Minerals
b. (petrographic, X-ray, chemical)
c. physical properties
These properties include:
- cleavage (splitting along definite planes)
- fracture (breaking irregularly)
- color
- streak (“chalk mark” when rubbed against unglazed porcelain)
- luster (reflection of ordinary light from its surfaces)
- specific gravity (ratio of the weight of the substance to that of an equal volume of water)
- hardness (based on an order of increasing hardness from 1 to 10)
1-talc
2- gypsum
3-calcite
4-fluorite
5-apatite
6-orthoclase
7-quartz
8- topaz
9-corundum
10-diamond
The (a) of soils is determined by the relative proportion of (b).
There are (c) textural classes of soils and these range from the (d).
(a) determines other soil properties such as (e), etc.
(a) can be approximated by (f) (rubbing a handful of moist soil), or by (g) (kneading a moistened soil samples into a soil wire/rod and molding it into a ring) and more precisely by the (h).
The (h) is based on the principle that (i) as shown by (j), where V is the (k), D is the (l) and K is a (m).
a. texture
b. sand (2.0 mm-0.05 mm), silt (0.05 mm-0.002 mm) and clay (<0.002 mm)
c. 12
d. fine-textured (clayey) to medium-textured (loamy) and coarse-textured (sandy) soils
e. porosity, ease of water movement (hydraulic conductivity), water holding capacity, internal drainage, tillage property, nutrient retention
f. “feel method”
g. “roll method”
h. hydrometer method (or by pipette method)
i. when in water suspension sand, silt and clay particles can be separated because of the difference in their settling velocity
j. Stokes’ Law: V=KD²
k. velocity of settling
l. diameter of soil particle
m. constant to correct for the effect of temperature
