Soil Science Exam 1

What is weathering?

Weathering is a biochemical process that involves both destruction and synthesis.

What is meant by the statement, weathering combines the process of destruction and synthesis? Give an example of these two processes in the weathering of a primary mineral.

Weathering is a biochemical process. The deconstruction by complete chemical breakdown. Synthesis: Hydrolysis

All of the following are factors of soil formation except: a. time b. parent material c. structure d. topography e. climate

c. structure

spodosols

coniferous

vertisols

constant turnover or inversion (shrink and swell, also known as gilgile)

What are the 12 soil orders?

Entisols, Inceptisols, Aridisols, Gelisols, Vertisols, Alfisols, Mollisols, Spodosols, Oxisols, Ultisols, Histosols, and Andisols

Which of the 12 soil orders are considered young?

Entisols, Inceptisols, Aridisols, Gelisols, and Vertisols

A-horizon

darkened by accumulation of organic matter

alfisols

deciduous forests

How are soils often defined?

dynamic natural bodies having properties derived from the combined effects of climate and biotic activities, as modified by topography, acting on parent materials over periods of time.

Oxisols

Fe and Al

How are metamorphic rocks formed?

Formed from other rocks by a process of change termed "metamorphism."

How are sedimentary rocks formed?

From the weathering products released from other, older rocks collect under water as sediment and eventually reconsolidate into new rock.

Organic Plant Material

Histosols

Which of the 12 soil orders are considered weird?

Histosols and Andisols

What is the soil taxonomy?

Order (12) Suborders(68) Great Group Subgroup Family Series (23,000)

Histosols

Organic parent material

Which of the 12 soil orders are considered old?

Oxisols and Ultisols

What organic deposits collectively called?

Peat

Fens

Peat-accumulating ponds with no outflow and little inflow. Calcium-rich mineral matter from the surrounding landscapes makes them relatively alkaline.

Climate

Precipitation and temperature. climate affects the profile of the soil.

What are the three groups of minerals that remain in well-weathered soils?

Silicate clays, very resistant end products (including iron and aluminum oxide clays), very resistant primary minerals, such as quartz.

biological weathering

when physical and chemical weathering both occur

Soil texture?

%sand, %silt, %clay present in soil

Inceptisols

(Incipient B)

Aridisols

(arid and dry environments)

Entisols

(recent)

What percent of sedimentary rocks cover the earth?

75% of Earth

Translocations

(soil, water, salt, clay, humus) earth worm movement from bottom to top. eroded sediment

What is soil made of?

45% Inorganic mineral solids, 5% organic matter, 25% soil solution (water), and 25% air

What is histosols Particle Density?

0.2

What are the four types of peat materials?

1. Moss peat, the remains of mosses such as sphagnum. 2. Herbaceous peat, residues of herbaceous plants such as sedges, reeds, and cattails. 3. Woody peat, from the remains of woody plants, including trees and shrubs. 4. Sedimentary peat, remains of aquatic plants and of fecal material of aquatic animals.

What are the five major factors that control the formation of soils?

1. Parent materials (geological or organic precursors to the soil) 2. Climate (primarily precipitation and temperature) 3. Biota (living organisms, especially native vegetation, microbes, soil animals, and increasingly human beings. 4. Topography (slope, aspect and landscape position) 5. Time (the period of time since the parent materials began to undergo soil formation)

Name the five factors affecting soil formation. With regard to each of these factors of soil formation, compare a forested rocky mountain slope to the semiarid grassland plain far below.

1. Parent materials (geological or organic precursors to the soil) Rocky Mountain: sedimentary, metamorphic, and igneous rocks. colluvium. Grassland plain: sedimentary rocks, 2. Climate (primarily precipitation and temperature) 3. Biota (living organisms, especially native vegetation, microbes, soil animals, and increasingly human beings) 4. Topography (slope, aspect, and landscape position) 5. Time (the period of time since the parent materials began to undergo soil formation.)

What factors affect Bulk Density?

1. Texture (sandy soils> un-compacted loams and clays) 2. Structure-soil organic matter content-tillage- tillage 3. compaction- tillage 4. presence of genetic pans (durian(genetic)-unlucky)

Four Processes (mechanisms of pedogenesis)

1. Transformations 2. Translocations 3. Additional 4. losses

Give two specific examples for each of the four broad processes of soil formation.

1. Transformations: occur when soil constituents are chemically or physically modified or destroyed and others are synthesized from the precursor materials. Ex. physical weathering to smaller particles 2. Translocations: involve the movement of inorganic and organic materials laterally within a horizon or vertically from one horizon up or down to another. Ex. incorporation of surface organic liter into the A and B horizons by certain earthworms, transport of B and C horizon material to the surface by mound-building termites, and the widespread burrowing actions of rodents. 3. Additions: inputs of materials to the developing soil profile from outside sources. Ex. the input of organic matter from fallen plant leaves and sloughed-off roots 4. Losses: materials lost from the soil profile by leaching to groundwater erosion of surface materials, or other forms of removal. Ex. microbial decomposition.

%Pore Space =

100(1-(Db/Dp))

What should you assume Particle Density is if it is not given?

2.65 g/cm^3

Explain the weathering significance of the ratio of silicon to aluminum in soil minerals.

A declining ratio of silicon to aluminum is considered an indicator of more complete weathering.

Give an example of how parent material may vary across large geographic regions on one hand, but may also vary within a small parcel of land on the other.

A great variety of soils occupy the regions covered by residual debris because of the marked differences in the nature of the rocks from which these materials evolved. The varied soils are also a reflection of wide differences in other soil-forming factors, such as climate and vegetation.

Which horizon is considered the top soil?

A-horizon

Which of the 12 soil orders are considered mature?

Alfisols, Mollisols, spodosols

Biota (native vegetation)

Basic cations Ca^2+,Mg^2+,Na+,K+ Acidic cations H+, Al^3+

How do colluvium, glacial till, and alluvium differ in appearance and agency of transport?

Colluvium is made up of poorly sorted rock fragments detached form the heights above and carried downslope, mostly by gravity, assisted in some cases by frost action. Glacial till is the materials deposited directly by the ice that are heterogeneous mixtures of debris, which vary in size from boulders to clay. Alluvium is made up of very fine materials from calmer floodwater (sediment).

additional

the addition of things to the soil

E-horizon

E-elluvial, zone of maximum elluviation (lower in clay and iron) light in color washed out of to B-horizon.

How is water involved in the main types of chemical weathering reactions?

Hydration. Intact water molecules may bind to a mineral. Hydrated oxides of iron and aluminum exemplify common products of hydration reactions. Dissolution: Water is capable of dissolving many minerals by hydrating the cations and anions until they become dissociated from each other and surrounded by water molecules.

What three classifications do the geologist classify rocks as?

Igneous, Sedimentary, and Metamorphic

What minerals are especially susceptible to oxidation-reduction reactions?

Iron, manganese, and sulfur

Glacial till

Mixtures deposited directly by the ice, the heterogeneous mixtures of debris, which vary in size from boulders to clay.

Most of the world's best agricultural soils are classified as either?

Mollisols and Alfisols

Have primary minerals been chemically altered?

NO, they were formed as molten lava solidified.

Inorganic parent material

Not transported=residual bedrock transported=1.water -rivers->alluvium(floodplain soils) -ocean->marine (costal plains) -lake->lacustrine ->glacial melt water: outwash 2. Gravity: colluvium 3. Wind- sand dunes -loess (windblown silt)-aerosal(clay) 4. Glaciers

Types of physical weathering (disintegration)

Temperature, Abrasion by water, ice, and wind, Plants and animals.

What is loess, and what are some of its properties as a parent material?

The windblown material composed primarily of silt with some very fine sand and course clay. Loess deposits tend to form silty soils of rather high fertility and potential productivity.

All mature soils have what in common?

They all have extensively well developed horizons.

Secondary minerals are recrystallized products of the chemical breakdown and/or alteration of primary minerals.

True

Toposequence

a group of soils that are different from one another primarily because of differences in the topographic positions which they occupy in the landscape

exfoliation

a type of physical weathering, the peeling away of the rock's outer layers

Ultisols

approaching oxisols (proto oxisols)

Macropore

big pores d>.08mm

All of the following are processes of soil formation except? a. additions b. translocations c. flocculations d. transformations e. losses

c. flocculations

The three general classes of alluvial deposits?

floodplains, alluvial fans, and deltas.

gelisols

frozen

muck

highly decomposed plant residues that have accumulated under conditions of excessive moisture

pedology

how soils are classified and formed, not from plant growth perspective

B-horizon

illuviation. clay, carbonates, iron, aluminum, and humus.

Time

in an arid climate an old soil might not show very much age same goes for if the soil is frozen.

Moraines

irregular ridges where glacial till is deposited.

colluvium

is 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.

What is igneous rock composed of?

light-colored quartz, muscovite, and feldspars, dark-colored biotite, augite, and hornblende.

Soil horizons?

master horizons, not all soils have all of them. some may only be C, R, etc.

C-horizon

minimal weathering

O-horizon

organic, undisturbed forests settings. very fragile. un-decomposed leaves on top layer. "100%" organic

losses

out of the top. soil erosion water

Bulk Density=

oven dry soil mass/volume of soil solids

Particle Density=

oven dry soil mass/volume of soil solids

Colluvium

parent material that has been deposited by gravity

Bogs

peat-accumulating ponds with no outflow and little inflow. They receive little calcium from the surrounding landscape and are therefore quite acidic.

Marshes

periodically inundated with shallow, slow-moving water and dominated by grasses and herbaceous plants. The everglades is avery large wetland area in Florida with both marshy and swampy components.

Swamps

periodically inundated with shallow, slow-moving water and dominated by shrubs and trees.

Transformations

physical increase in surface area biochemical-oxidation reactions acid hydrolysis- k feldspar + H+.... Complexation

ecological functions of soil

plant growth medium, building foundation, H20 storage, filtration, decompose (recycling), home for creatures (biota), control of atmosphere (methane, CO2, Nitrous Oxide)

mollisols

prairie

loess:

primarily silt-sized particles transported by wind

Parent Material

residual bedrock, alluvial, river runoff, and glacial till-unsorted.

Micropore

small pores d<.08mm

pedogenesis

soil formation- the process where non soil becomes soil- water is needed for this process of soil formation

edaphology

soil from the view of the support of plant life.

thixotropy

soil which is though to be solid liquifies (landslide)

effective precipitation

that portion of the total precipitation that becomes available for plant growth or for the promotion of soil formation

Which horizon do many of the soils not have?

the E-horizon

bioturbation

the mixing of soil caused by the burrowing activities of soil animals

Exfoliation?

the peeling away of the outer layer of a rock

Topogrophy

toposequence (catena) only difference in A,B,C is location making them different.

R-horizon

un-weathered bedrock

oxisol

very old soil. red in color because of rust

Andisols

volcanic ash parent material

according to Hillel, the Earth and the atmosphere are engaged in an endless reciprocal passing game whose main article of exchange is?

water