Soils Test 1

  1. Major functions of soils in the ecosystem?
    • 1. Recyler of Raw Materials
    • 2. Medium for Plants
    • 3. Regulate H2O supply
    • 4. Habitat for Soil Organisms
    • 5. Modifier of Atmosphere
  2. Soil colloids
    Organic and inorganic matter with very small particle size and a correspondingly large surface area per unit of mass.
  3. Resilience
    The capacity of a soil to return to its original state after a disturbance
  4. Soil horizon
    A layer of soil, approximately parallel to the soil surface, differing in properties and characteristics from adjacent layers below or above it.
  5. Humus
    The more or less stable faction of the soil organic matter remaining after the major portions of added plant and animal residues have decomposed. Usually dark in color
  6. Furrow (slice)
    The uppermost layer of an arable soil to the depth of primary tillage; the layer of soil sliced away from the rest of the profile and inverted by a moldboard plow.
  7. Clay
    • A soil separate consisting of particles less than 0.002 mm
    • A soil textural class containing more than 40% clay, less than 45% sand and less than 40% silt
  8. What three ways is the word mineral used in soil science?
    • 1. as a general adjective to describe inorganic materials derived from rocks
    • 2. as a specific noun to refer to distinct minerals found in nature such as quartz and fieldspars
    • 3. as an adjective to describe chemical elements, such as nitrogen and phosphorus, in their inorganic state in contrast to their occurence as a part of organic compounds
  9. Difference between mineral and organic soils?
    • Mineral soils are predominated by weathered, inorganic materials.
    • Organic soils are formed by decayed plant and animal residues.
  10. Pedology
    • considers soils as a natural entity, a biochemically weathered and synthesized product of nature.
    • soil genesis and development, profile formation, classification and description are studied.
  11. Edaphalogy
    Study of soils from the standpoint of higher plants. Emphasis on the role of soil in plant production.
  12. Soil structure
    • The combination or arrangement of primary soil particles into secondary particles, units or peds.
    • Classified and characterized on basis of size, shape and degree of distinctiveness into classes (v. fine to v. coarse), types (platy, prismatic, columnar, blocky, etc.) and grades (structureless, weak, moderate, strong)
  13. Soil structure v. soil texture?
    structure is the way the particles are arranged together, while texture is the relative amounts of different sizes of particles
  14. Soil solution
    • The aqueous liquid phase of the soil and its solutes, consisting of ions dissociated from the surfaces of soil particles and of other soil materials.
    • A more accurate name than soil water, because it contains hundreds of dissolved organic and inorganic substances.
  15. Dispersion is caused by what elements?
    • Sodium (this causes serious situations involving water movement and plant growth)
    • K - to a lesser extent
    • Dispersion is encouraged by high pH values
  16. What elements are flocculating agents?
    aluminum, hydrogen, magnesium or calcium
  17. How can you reduce electronegativity?
    • 1. Lower soil pH (replacing ions by hydrogen or aluminum will result in a lower pH)
    • 2. Replacing the adsorbed ion with a di or trivalent ion such as Ca2+, Mg2+, or Al3+
    • 3. Replacing the adsorbed ion with an ion of a smaller size
  18. If a soil has a large quantity of quartz, what can that tell you about its age?
    It's an old soil
  19. If a soil has a lot of K, what does that tell you about its age?
    It's a young soil
  20. How old is a soil with a lot of Al or Al and K?
    It's somewhere between young (K) and old (quartz)
  21. How do you calculate the surface area of a sphere?
    • 6xV
    • divided by
    • diameter of its smallest sphere
    • should be in cm2
  22. What did we use hydroflouric acid for in the mineral staining exercise?
    To etch the sand particles
  23. What did we use the sodium colbalti nitrate for in lab?
    To stain sands and determine the amount of K in soil (it turns yellow)
  24. Materials that contain hydrogen, calcium and aluminum are good at what?
    flocculating agents
  25. Will clays be dispersed or flocculated in well-drained soils?
  26. Dispersed means what?
    Particles will be in suspension
  27. Flocculation means?
    Particles will settle out
  28. The surface area of clay has a lot of (positive or negative) particles?
    • Negative
    • This means positive charges will be attracted
  29. What elements are the best choice for leaky ponds?
    • Ca and Mg
    • (HCl lowers the pH so quick that fish die, aluminum isn't so healthy)
  30. The clay of a soil consists principally of what products?
    the insoluble end products of the chemical weathering of the primary minerals from the silt and sand fractions of the soil.
  31. T/F: The negative charges of clay surfaces store the nutrient anions liberated by the chemical weathering of silt and sand particles and also the nutrient cations that are added as fertilizers.
    False. Clay stores cations (not anions)
  32. Principal functions of clay in a soil?
    • storage of plant nutrients and moisture
    • cementation of groups of particles into soil aggregates
  33. In what three ways may clay be characterized?
    • 1. according to the amounts of moisture it will retain under different moisture stresses
    • 2. according to the amounts of exchangeable cations it will hold
    • 3. according to the energy with which it retains different cations
  34. sand and silt consist of primarly what products?
    discrete primary minerals
  35. Sand and silt are too small to be i.d.'d by crystal shape, color, and hardness. How do we identify them?
    Optical, by refraction, diffraction, the rotation of polarized light and fluorescence under ultraviolet light. We stained them in lab.
  36. Where in the state would you find older soils?
    Ozark uplift, you'll find quartz and various clays
  37. Where would you find newer soils in MO?
    Along the MO River
  38. Do soils derived from loess and glacial till contain many non-weathered primary minerals?
  39. The capacity of a soil to maintain its productivity under heavy cropping over a long period of years is associated primarily with what?
    The percentage of nutrient containing minerals principally in the silt fraction of the soil
  40. Size of sand particles
    2.0 to 0.05 mm
  41. Size of silt particles?
    0.05 to 0.002 mm
  42. Size of clay particles?
    0.002 mm and less
  43. Mineral fractions of soil, other than gravel and stones, divided into groups according to size are known as
    soil separates
  44. Particle size analysis (or mechanical analysis) can be done by sieving and sedimentation. When would you use sedimentation?
    With particles less than 0.05 mm.
  45. What does Stokes Law of Sedimentation do?
    • It relates the rate (velocity) that a particle will fall in a liquid to the size of the particle.
    • (A particle falls in a viscous medium with an increasing velocity until the downward force is just balanced by the frictional resistance, after which the particle falls with a uniform velocity.)
  46. You can use decantation, pipette sampling or the hydrometer to perform a quantitative separation by Stoke's sedimentation method. What did we do?
    Used a hydrometer
  47. During the sedimentation process, sand falls first (it's the heaviest). What were we left with after 40 seconds, and again after two hours?
    Silt and clay after 40 seconds, clay after 2 hours
  48. Loam
    • textural class name for soil having a moderate amount of sand silt and clay
    • Sand (23-52%) Silt (28 to 50%) Clay (7 to 27%)
  49. How do you adjust your hydrometer reading for temp?
    • For every degree above the reference temp, add 0.2 to the observed reading.
    • For every degree below the reference temp, subtract 0.2 from the observed reading.
  50. pedology
    considers soils as a natural entity
  51. edaphalogy
    considers from the standpoint of plants. emphasis on soil is its role in plant production
  52. primary minerals
    haven't been chemically altered
  53. secondary minerals
    resulting from the decomposition of a primary mineral
  54. soil profile
    a vertical section through all of the horizons and extending into the parent material
  55. regolith
    the unconsolidated matle of weathered rock and soil materails on the earth's surface
  56. soil colloids
    organic and inorganic matter with very small particle size and correspondingly large surface area per unit of mass
  57. saprolite
    soft, friable, weathered bedrock that retains the fabric and structure of parent material but is porous and can be dug with a spade
  58. solum
    upper and most weathered part of the soil profile (A, E & B horizons)
  59. furrow (slice)
    the uppermost layer of arable soil to the depth of primary tillage
  60. soil productivity
    • capacity to produce a specified plant or plants under a system of management
    • expressed in yields
  61. soil solution
    • the aqueous liquid phase of soil and solutes (aka water and dissolved salts)
    • better term than soil water, because it contains more than just soil.
  62. humus
    usually dark in color, organic matter after decomp
  63. soil quality
    capacity to function within natural or managed boundaries, to sustain plant and animal productivity
  64. soil texture
    relative proportions of various separates in a soil
  65. soil resilience
    capacity to return to original state after a disturbance
  66. soil horizon
    a layer of soil, approximately parallel to the soil surface, differentiated from adjacent layers above and below
  67. soil fertility
    quality of a soil that enables it to provide essential chemical elements in quantities and proportions for the growth of specified plants
  68. If a soil has a pH of 6.0 what is it classified as?
  69. If a soil has a pH of 7.0 what is it?
  70. If a soil has a pH of 8.0, what is it?
  71. How is the soil a modifier of the atmosphere?
    • It can produce dust in the atmosphere
    • evaporation of soil moisture is a major source of water vapor in the atmosphere (affects temp, composition and wx patterns) 
  72. How does the CO2 level and moisture percentage of air in soil pores compare with above ground atmosphere?
    • Soil air generally has a higher moisture content than the atmosphere
    • relative humidity of soil air approaches 100% unless it's very dry
    • CO2 is usually much higher and O2 lower than those found in the atmosphere
  73. The amount and composition of air in the soil is largely determined by what?
    The amount of water in the soil
  74. What happens to the air to water ratio from the surface to subsoil horizons?
    Compared to soil surface layers, subsoils tend to contain less organic matter, less total pore space and a larger proportion of small pores (micropores) which tend to be filled with water rather than air.
  75. What are the four major components (by volume) of a representative loam surface soil? Which components are more easily changed?
    • Mineral (45%), Organic (5%), Water (20-30%) and Air (20-30%)
    • Water and Air are most easily changed
  76. residuum
    unconsolidated and partly weathered materials accumulated by disintegration of consolidated rock in place
  77. colluvial materials
    Poorly sorted rock fragments detached from heights and carried downslope (gravity)
  78. organic deposits (peats)
    unconsolidated soil material consisting largely of undecomposed or slightly decomposed organic matter accumulated under conditions of excessive moisture
  79. deltas
    alluvial deposits formed where a stream or river drops its sediment load upon entering a quieter body of water
  80. alluvial fans
    fan-shaped alluvium deposited at the mouth of a canyon or ravine where debris-laden waters fan out, slow down and deposit their burdens
  81. loess
    material transported and deposited by the wind and predominantly consisting of silt-sized particles
  82. moraines
    the irregular ridges much glacial till is deposited in
  83. lacustrine deposits
    • material deposited in lake water and later exposed by lowering the water level or elevation of the land
    • fresh water - comes from glacial lakes
    • mainly in N. part of U.S.
  84. kames
    conical hill or ridge of sand or gravel deposited in contact with glacial ice
  85. drumlin
    long smooth cigar shaped low hills of glacial till with long axis parallel to the direction of ice movement
  86. eskers
    a narrow ridge of gravelly or sandy glacial material deposited by a stream in an ice-walled valley or tunnel in a receding glacier
  87. 5 major soil-forming factors on soil profile development
    parent materials, climate, biota, topography, time
  88. igneous rocks?
    made from molten lava
  89. sedimentary rocks?
    weathered products of other rocks
  90. metamorphic
    both igneous and sedimentary
  91. what types of rocks are most commonly found in southwestern Missouri?
    sedimentary, mostly limestone and shale
  92. List three examples of the physical weathering process?
    shrink-swell, erosion-deposition, plant roots, earthworms, microbes
  93. what types of weathering process usually dominate in arid areas? humid areas?
    • arid - physical processes dominate
    • humind, tropical areas - decomposition and recomination are most prominent
  94. Examples of solubility changes in chemical weathering reactions?
    • hydrolysis (water on microline)
    • dissolution (gypsum dissolving in water)
    • acid reactions (when carbon dioxide dissolves in water, the carbonic acid produced hastes the dissolution of calcite in limestone or marble)
  95. examples of structural changes in chemical weathering reactions?
    • hydration (ex: hydrated oxides of iron and aluminum)
    • oxidation-reduction (Iron is oxidized from Fe (II) to Fe (III)
    • Complexation (oxalic acide forms a soluble complex with Al from muscovite, destroying the structure and releasing dissolved ions of K)
  96. eluviated horizon in the soil profile?
    • E is the zone of max. eluviation
    • eluviated = washed out
  97. illuviated horizon in the soil profile?
    • B is the zone of maximum illuviation
    • illuviated = washed in
  98. O horizon
    • organic layer in various stages of decomp
    • (found in forested or forest/prairie)
  99. A horizon
    top most mineral horizon - dark colored
  100. E horizon
    • zone of max eluviation (washed or leached out)
    • Lighter in color, not found in prairie
  101. B horizon
    • zone of maximum illuvation (washed in)
    • deposition of colloids, soluble minerals and particles to an underlying soil
    • clay and aluminum oxides accumulate here
  102. C Horizon
    Unconsolidated, non weathered materials (usually parent material)
  103. R layers
    consolidated rock, with little evidence of weathering
  104. How do you know the difference between master horizons, transition horizons and subordinate horizons?
    • Master horizons - capital letter
    • Transition horizons - combination of two capital letters
    • Subordinate horizons - small letters after major horizon designation
    • (subdivisions of subordinate horizons have numbers after small letter)
  105. inherited soil properties
    • color, texture, structure
    • young soils get more inherited properties
  106. aquired soil properties
    clay accumulation, organic matter, drainage characteristics, etc.
  107. Hydration
    • reaction of a chemical with water to form a chemical compound
    • look for the dot in the product line - it says water is a part of the structure
  108. hydrolisis
    • changes the solubility
    • it's a reaction between mineral and water - water molecules split into their hydrogen and hydroxyl components and the hydrogen often replaces a cation from the mineral structure
    • look for OH
  109. acidification
    • weathering is accelerated by the presence of acids, which increase the activity of hydrogen ions in water
    • (look for acids: H2CO3; HNO3; H2SO4)
  110. Oxidation reduction
    • Iron, Manganese, or Sulfur minerals expecially susceptible
    • loss of electrons (oxidation), gain of electrons (reduction)
    • water saturation means more reduction because you're pushing out the air
  111. Dissolution
    • water dissolves minerals by hydrating the cations and anions until they become dissassociated with each other and surrounded by water molecules
    • look for combos to be split
  112. Complexation
    • organic acid dissolution
    • look for 2K+
  113. Five soil forming factors?
    • Temperature
    • Parent Material
    • Time
    • Biota
    • Topography
  114. Telmatic
    herbaceous peat
  115. Terrestic
    Woody peat
  116. Limnic or sedimentary peat
    includes anything that isn't moss, herbaceous or woody peat (excretions from earth worms, microbes fit here)
  117. Types of alluvial (flowing water) deposits
    • Flood plains (aka river bottoms - fertile because the water brings in new parent materials)
    • Terraces (old flood plains no longer under frequent flooding)
    • Alluvial fans (occurs when changes elevation)
    • Deltas (extensions of flood plains, occur where two rivers or streams intersect)
Card Set
Soils Test 1
Soils, Test 1