Lab 2 Flashcards
1
Q
Pedogenesis
A
The process in which souls grow, develop, erode and slowly transform into other soils over time
2
Q
Pedogenesis begins with…
A
Parent material
3
Q
Most soils derive from…
A
Inorganic parent materials acted upon by additions, losses, translocations, and transformations
4
Q
Weathering
A
Minerals and rocks physically disintegrate into smaller particle sizes, and chemically decompose into altered chemical and mineralogical products
5
Q
Mineral
A
Naturally occurring, inorganic, crystalline solid having a definite chemical composition and predictable physical properties
6
Q
Rocks are made of ______and minerals are made of _______
A
Minerals, elements
7
Q
Crystalline
A
A minerals atoms are arranged in an orderly and repeatable manner; they are not random
8
Q
Amorphous/noncrystalline
A
A substance having randomly arranged atoms
9
Q
Nearly 3/4 of earths crust is made up of what two elements (mass)
A
Oxygen and silicone
10
Q
Eight most common elements in the earths crust
A
Oxygen, silicon, aluminum, iron, calcium, sodium, potassium, and magnesium
11
Q
Seven classes of minerals
A
Sulfides, oxides & hydroxides, halides, carbonates, sulfates, phosphates, and silicates
12
Q
Physical properties of minerals
A
Color, luster, and cleavage & fracture
13
Q
Luster
A
The nature of light reflected from a minerals surface
14
Q
Cleavage & fracture
A
A minerals tendency to break along certain predictable directions when the mineral is struck by a hammer
15
Q
Sulfides
A
Readily oxidized in moist soils
Ex. Pyrite and sphalerite
16
Q
Oxides
A
Readily oxidized, producing red colors
Ex. Hematite
17
Q
Halides
A
Rock salt; sometimes found in desert soils
Ex. Halite and sylvite
18
Q
Carbonates
A
Calcite - Calcareous; reacts to acid; weathers easily in moist soils;
Dolomite - calcareous; less reactive than
19
Q
Sulfates
A
A common agricultural amendment; sometimes found in desert soils
Ex. Gypsum
20
Q
Phosphates
A
The only significant source of phosphorus
21
Q
Silicates
A
The most common mineral classification, made up of silicates
Ex. Olivine, pyroxene, amphibole, micas, feldspars, quartz, serpentine
22
Q
Possible cleavage directions
A
1, 2, 3, 4 or 6
23
Q
Hardness
A
Determined by the resistance of a minerals surface to scratching by various instruments of known hardness
24
Q
18 essential element for plant growth
A
C HOPKNS CaFe Mg B Mn CuZn Cl CoMo Ni
25
Essential elements that are released form the weathering of minerals for plant use
Iron, calcium, magnesium, and potassium
26
What are the plant-essential elements
Carbon, hydrogen, oxygen, and nitrogen
27
Four general processes responsible for soil formation
Additions, transformations, translocations and losses
28
Rocks
The most common are made of minerals, however some are made of noncrystalline materials
29
Igneous rocks
Forms when molten material (magma) cools and solidifies
30
Intrusive igneous
Magma that remains at depth and cools slowly, forming large grains
31
Extrusive igneous
Magma that erupts and cools rapidly, amorphous or microcrystalline
32
Felsic igneous
Light colored, derived from silica/potassium rich magma, dominated by quartz and orthoclase
33
Mafic Igneous
Dark colored, characterized by calcic plagioclase and ferromagnesian minerals
34
Igneous rock classifications
Felsic, intermediate, mafic, Ultramafic
35
Sedimentary rocks
Make up the bulk of the earths continental crust, can be clastic or nonclastic
36
Clastic sedimentary
Consist of fragments of previously existing rocks that have been transported to a new location, where they wet deposited and buried layer upon later and cemented togeather
37
Nonclastic sedimentary
Form by chemical precipitation of dissolved of dissolved slats and by biochemical precipitation of organically derived compounds in water
38
What organisms generate nonclastic rocks
Bacteria, algae, diatoms, corals, and mollusks
39
Clastic rocks ex.
Clay stone, siltstone, mudstone, shale, sandstones & wacke & arenite, conglomerate
40
Metamorphic rocks
Form primarily by the application of extremely high heat and pressure to some previously existing rock
41
What rock is most susceptible to metamorphosis
Sedimentary
42
Foliated metamorphic
Consist of minerals this are aligned or oriented to yield a somewhat stratified or layered appearance
43
Nonfoliated metamorphic
About equally arranged in all directions, giving them a more uniformly massive appearance
44
Foliated Metamorphic rocks ex.
Slate, schist, gneiss
45
Non clastic metamorphic rocks ex.
Marble, quartzite, serpentinite
46
Nonclastic sedimentary rocks ex.
Limestone, dolomite, gypsum, chert
47
Greater fertility (more plant nutrients)
More elements
Ex. Granite and gabbro
48
Higher clay content
Smaller crystals = more clay
Ex. Wacke and basalt
49
Greater gravel content
Bigger crystals = more gravel
50
Greater gravel content
Bigger crystals = more gravel
51
Greater water holding capacity
More clay and higher porosity
52
Higher pH
Lime content
53
Greater soil depth after weathering
Faster weathering = greater soil depth after
54
Weathering
Breaks rocks and minerals down, resulting in the production of soils, occurs via two processes: physical disintegration and chemical decomposition
55
Physical disintegration
Causes rock masses to split apart or to abrade and wear away from the larger rock surface
56
Glacial physical disintegration
Freezing and thawing, abrasion by particles suspended in wind or water, and grinding caused by glaciers result in disintegration
57
Chemical decomposition
Progresses more rapidly when more corners, edges, and surfaces are available for chemical reactions to occur
58
What type of environment enhances chemical decomposition
Warm and wet
59
Chemical decomposition is a combination of five major weathering processes
Carbonation, hydration, hydrolysis, oxidation-reduction and solution
60
What causes glacial till to have a high pH
The resulting hydrolysis reaction of the fine particles hydrolyzing with the water
61
More H+ =
Lower pH, more acidic
62
More OH- =
Higher pH, more basic
63
Carbonation and solution
The metabolic activities of plant roots and microorganisms produce an abundance of CO2 within soil pores, this CO2 reacts with soil water to produce most of the carbonic acid found in soils
64
Carbonic acid ionization
Carbonic acid can ionize into acidic hydrogen ions (H+) and bicarbonate (HCO-), not all carbonic acid molecules will release hydrogen ions (H+) due to the nature of weak acids
65
Law of mass action
The directions of a chemical reaction depends on the concentration of the reactants and products
66
Rainwater and carbonic acid
When rainwater which contains dissolved CO2 enters the soil it forms carbonic acid
67
Calcium bicarbonates dissolving
Calcium bicarbonate dissolves slowly and releases soluble calcium ions (Ca2+) for plant uptake or possible leaching downward through the soil when excessive rainfall or irrigation occurs
68
Loss of calcite minerals leads to
The development of acidic soils, carbonate hardpans, and the formation of huge underground caverns
69
“Hard water”
Calcium bicarbonate in the ground water is the major reason why limestone ground water is considered “hard water”
70
Soluble calcium bicarbonate rxn major effects
1) surface soil will become acidic and the pH will decrease due to increased rainfall and CO2 production
2) soluble calcium is made available to plants
Eventually soil becomes depleted of calcium - results in a loss of overall plant nutrition and soil fertility
71
How does physical weathering affect the rate of hydrolysis
Speeds up the process
72
How did blowing your breath into the water affect the pH and what caused this?
The pH lowered slightly - more acidic. The CO2 from my breath caused a change in pH
73
What happens to CaCO3 (calcite) in high lime content soils that receive abundant rainfall or irrigation water annually for many years
It would desolve
74
Which rocks are most susceptible to chemical decomposition by the carbonation reaction
Sedimentary rocks
75
Redox reactions
Substance losing electron is oxidized, component accepting electrons becomes reduced
OIL RIG
76
Electron transfer as a chem weathering form
Constitutes a form of chemical weathering that disrupts the minerals atomic structure, releasing several elements and leading to the development of new compounds including clay minerals
77
When soil is moist and well aerated
Iron tends to become oxidized
78
Oxidized iron occurs
Where oxygen is present in well-drained soils and produces red, yellow, or brown colors in soils
79
Reduced iron exists
In flooded or very poorly drained soils and produces black, gray, olive and blue colors
80
Reduced iron exists
In flooded or very poorly drained soils and produces black, gray, olive and blue colors
81
Alternating periods of oxidation and reduction caused by fluctuating water tables results in
Redoximorphic features such as concentrations and depletions in the soil
82
Continuous strongly reducing conditions caused by long term water logging form
Gleyed conditions, which have dark gray to blue to black soil colors
83
Continuous strongly reducing conditions caused by long term water logging form
Gleyed conditions, which have dark gray to blue to black soil colors
84
In the field what soil Topographic or slope position would be most conductive to the formation of reducing conditions or gleyed soils
Flood plain bc water accumulation with little to no drainage
85
In the field what soil topographic or slope position would be most conductive to the formation of strongly oxidizing conditions in soil
Back slope bc it’s the steepest and allows for better drainage
86
In the field what soil topographic or slope position would be most conductive to the formation of strongly oxidizing conditions in soil
Back slope bc it’s the steepest and allows for better drainage
87
Rocks with an abundance of iron containing minerals weather easily and become reddish brown when exposed to the atmosphere why?
C of the oxidation process that forms iron oxides which weakens rock structure and allows it to weather faster
88
How do the horizons and overall depths of these two soils (Zaca and Baywood) vary and how is this inflicted by the different parent materials?
Zaca has more A horizons and baywood has more C horizons - bc how they lay currently is dependent on how they were transported as parent material
89
How do the horizons and overall depths of these two soils (Zaca and Baywood) vary and how is this inflicted by the different parent materials?
Zaca has more A horizons and baywood has more C horizons - bc how they lay currently is dependent on how they were transported as parent material
90
Is the Zaca forming from the underlying bedrock or was it transported by wind, water, etc. how can you tell?
Zaca parent material was residual meaning it formed from the underlying bedrock, apparent by the presence of thinly layered mud
91
Is the baywood forming from the underlying bedrock or was it transported by wind, water, etc. how can you tell?
Soil was transported by wind bc the parent material is aeolian sand
