question

the dimensions of the earth.

answer

Diameter: 7973mi, Circumference: 25048mi, SA:200million mi^2, Earths crust: 35mi

question

2. Understand that definitions of soil depend strongly on the concerns of those making the definitions. so who?

answer

Agriculture, ecology/life, geology, environment, public health

question

the parameters related to soil composition for an idealized surface soil.

answer

50% pore space, 50% solids (organic matter and particles)

question

basic functions of soils in the environment.

answer

regulator of water supplies. medium for plant growth. habitat for biota. public health. storage of raw materials

question

4 basic processes involved in soil formation

answer

Transformations, Translocations, Additions, losses

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Transformtions

answer

Chemical or physical modifications of elements in soil Critical in the Creation of the Parent Material and Alteration of Parent Material to Secondary Components

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Additions

answer

Input of organic matter from leaves, roots, organisms Input of dust particles on the soil surface, water-deposited solids Manure or fertilizer application

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Losses

answer

Erosion of soil materials Decomposition of organic matter Movement of salts, clays, O.M.

question

Translocations

answer

loss of: Fe/Al oxides, Organic Matter, Iron and clay from water

question

the basics of weathering.

answer

Critical to Soil Formation, Physical and Chemical Alteration and Reorganization of Rocks and Minerals. Critical in the Creation of the Parent Material and Alteration of Parent Material to Secondary Components

question

the 5 soil forming factors and what they mean or imply.

answer

Climate Organisms/Biota Relief (Topography) parent material time

question

type of parent material that dominates Florida's soils.

answer

from Sandy and Clayey Marine and Alluvial Sediments deposited over limestone Bedrock

question

origin of the sediments that ultimately formed the parent materials for Florida's soils.

answer

Parent Materials Resulted from Influx of Continental Sediments

question

parent material

answer

Original Material

question

Climate

answer

Temperature, Moisture

question

Organisms/biota

answer

Vegetation, Macro, Micro

question

Relief (Topography)

answer

Altitude, Slope

question

Time

answer

Controls extent of other factors

question

how temperature and rainfall impact soil formation.

answer

accelerate soil formation- Heat increases rates of physicochemical processes-Water increases weathering rates and translocations

question

why soils in Florida tend to be more highly developed than soils in the S.W. United States.

answer

climate: High temperatures and rainfall accelerate soil formation Heat increases rates of physicochemical processes Water increases weathering rates and translocations

question

What is pedogensis?

answer

The process of soil formation as the result of the combination of soil forming factors and processes.

question

What are soil horizons?

answer

Roughly parallel layers in the soil with varying composition and properties

question

6 master horizons discussed and be able to identify/recognize features of each.

answer

O A E B C R

question

O horizon

answer

Organic horizon formed above the mineral soil. Derived from decomposition of plant and animal residues At least 20% organic Range in thickness from absent to meters thick.

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A Horizon

answer

Topmost mineral horizon (topsoil) Subject to significant weathering Accumulates organic material Often darker than soil below. High in plant roots, biotic activity Zone of gas and water exchange

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E Horizon

answer

Zone of Eluviation, E = Elluviation = exit, Maximum Losses by Translocation, Organic matter, Clays, Carbonates, Fe, Al oxides, Generally light colored

question

B Horizon

answer

Accumulates material lost from above, or forms in place. (translocation, transformation) Usually a Zone of Illuviation (additions, translocation). Clay, O.M., Fe/Al, salts Soil structure Potential color development Potentially high reactivity (concentration of secondary minerals/O.M.)

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C Horizon

answer

Closely resembles parent material Unconsolidated Little or no evidence of Alteration or development

question

R Horizon

answer

bedrock

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Subordinate Distinctions of the O horizon

answer

Oa-Highly decomposed organic material (sapric) Oe-Moderately decomposed organic material (hemic) Oi-Slightly decomposed organic material (fibric)

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A horizon subordinate distinctions

answer

p = disturbed, plowed

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Subordinate Distinctions of the B Master Horizon

answer

Bt=accumulation of silicate clays Bh=illuvial accumulation of organic matter Bw="Weak" development of color or structure Bg=Gleying - wet, low oxygen

question

basic relationship between time and the extent or degree of soil development.

answer

...

question

vertical horizon subdivisions vs transitional horizons.

answer

Vertical: Characterized by similar master and/or subordinate properties separated by "degree". Transitional layers between master horizons-in between subordinate and dominant

question

generalizations presented with respect to soil color

answer

Grey to Black-Organic Matter Orange to Red-Iron oxides Light Colors-Removal of materials

question

3 components to soil color and what they mean.

answer

Hue, chroma, value

question

hue

answer

dominant spectral color; related to the wavelength of light. Related to the proportions of red to yellow.

question

value

answer

related to total amount of light reflected.

question

chroma

answer

measure of the strength of spectral color

question

3 particle size separates and the range in their sizes.

answer

Sand (2.0 - 0.05) Quartz Silt (0.05 - 0.002) Quartz /Feldspars/mica Clay (<0.002) Secondary minerals

question

dominant minerals in each particle size

answer

Sand and silt fractions are dominated by primary minerals The clay fraction is dominated by reactive secondary minerals

question

soil texture

answer

Soil texture refers to the relative amounts of three distinct particle size separates comprising the mineral component of soils.

question

how texture generally affects overall porosity

answer

All else being equal, finer-textured soils have greater overall porosity than coarse-textured soils

question

how texture generally affects pore size distribution

answer

Large Particles Yield Large Pores

question

how texture affects water and gas movement in soils.

answer

clay-Air and Water Movement is Very Slow Water Retention is High Coarse-Textured Soils:Large Pore Spaces Rapid Water Movement Poor Water Retention Gas Exchange Facilitated

question

relationship between soil texture and specific surface area; why is it important?

answer

Water Movement and Potential Reactivity

question

what Stokes' Law indicates and how it is used in the hydrometer method to assess soil texture.

answer

Stokes' Law allows determination of the time required for different particle size separates to settle from a suspension Determination of the amount of materials settled yields texture 1 minute Sand settles out 6 hours Silt settles out V = K D2

question

hydrometer method and how to calculate % sand, silt, and clay given appropriate measurements.

answer

As particles settle out, the suspension becomes less dense. The hydrometer measures the density of the suspension. The units are g/L. . In dense suspensions, the hydrometer floats higher in less dense suspensions it sinks. is calibrated to read zero in pure water at 20 degrees

question

hydrometer method

answer

Add __ g soil to 1 liter of water 1 min, difference in g is sand settled. 6hrs is clay. put each __g over full __g amount *100%= measurements

question

numerical value for soil particle density.

answer

2.65 g/cm3

question

how to compute soil bulk density and what it is.

answer

BD = mass OD soil volume solids + pores Density of soil including the particles and the pore spaces Based on the Number of Particles Packed into a Given Volume B.D. ranges between 1.0 and 1.6 g/cm3 (for mineral soil with 1 - 5% organic matter)

question

how texture, organic matter, aggregation, compaction, and depth in profile affect porosity and bulk density.

answer

Compaction increases soil density Compaction from above,Lower organic matter,Fewer roots increases soil density. Organic matter increases porosity, decreases BD Depth in profile decreases porosity, increases BD Compaction decreases porosity, increases BD Factors which increase porosity, decrease density

question

the conceptual and quantitative relationship between BD and porosity.

answer

Bulk density high - porosity low Bulk density low - porosity high Factors which increase porosity, decrease density.

question

total porosity vs pore size distribution

answer

total porosity-Indicates the fraction of a total soil volume that is pore space, indicates the maximum volume of water and gases a soil can hold Vp/Vs Pore size distribution- Macro, meso and micropores. macropores > 0.08 mm in diameter large, freely draining sands, inter-aggregate pores large enough to accommodate roots Mesopores Moderate Size 0.08 - 0.03 mm Retain water well against drainage Accommodate fungi and root hairs Micropores < 0.03 mm in diameter small, storage of water Accommodate Bacteria clays, intra-aggregate pores

question

Fine-Textured Soils Compacted, High Density Soils High Organic Matter Soils -whats the reactivity

answer

Small pores slow water and gas movement, but increase contact between soil solution and soil particles, increasing reactivity

question

what soil structure is and how it affects soil porosity and pore size distribution

answer

it affects: the movement of water into and through soil; the degree of aeration; the ability of crop roots to grow through the soil profile; and the ability of the soil to resist soil erosion. Large pores drain freely, small pores store water effectively Poor soil structure can inhibit infiltration of water, water movement, growth of roots.

question

what type, class, and grade indicate relative to soil structure. Know the structural types

answer

types( shapes): Granular,Platy,Block-like, Prism-like class(size), grade (strength)

question

how texture, density, and structure impact water and gas movement and potential reactivity.

answer

Spheriodal soils have a granular structure. The aggregates are 1- 10 mm (1/25- 2/5 in.) in diameter with rounded corners. This structure is usually seen in the A horizon or the upper layer of fine or medium-textured soils. Granular structure in the seed or transplant zone is important for good contact and early establishment. Blocky soil aggregates are often larger in size (5- 50 mm or 1/5- 2 in. in diameter) and form irregular-shaped or cube-like blocks. This structure promotes good drainage, aeration and root penetration. Usually these structures are found in the B horizon or just below the colour change in many soils. Blocky structures greater than 50 mm (2 in.) in diameter are often an indication of compaction or soil management problems. Platy soils form thin layers or horizontal planes. This type of structure can be found in both surface and subsurface soil horizons. It is commonly seen in undisturbed or no-till soils. Platy structures in sandy soils often indicate compaction problems.

question

the boiling and freezing point of water.

answer

The freezing point of water, of course, is 0 degrees Celsius and the boiling point is 100 degrees, giving us a liquid range of 100 degrees.

question

how hydrogen and oxygen are bonded within a single water molecule. Know the name of the bond.

answer

The bonding of hydrogen and oxygen in a water molecule is covalent. The hydrogen atoms share their single electron with oxygen thereby completing its valence shell, while oxygen, in turn, shares one of its lone electrons with each hydrogen completing their valence shells.

question

how water is made polar.

answer

oxygen is highly electronegative, In a chemical bond, electrons tend to be drawn toward oxygen, and away from other atoms to which it is bonded. The electrons tend to cluster near the oxygen The overall electrical charge on the molecule is zero, There is a slight partial negative charge near the oxygen atom, and a slight partial positive charge near the hydrogen atoms in the molecule

question

polarity and how it impacts bonding between water molecules in the liquid and solid.

answer

So, in liquid as well as solid water or ice, water molecules are linked together electrostatically which imparts unusual stability and strength. This accounts, for example, for water's unusually high boiling point compared to other liquids. tends to keep water in the liquid phase at higher temperatures than compositionally similar liquids like hydrogen sulfide. So, evaporation requires far less energy resulting in a much lower boiling point.

question

name of the bond that exists between water molecules in the liquid and solid state.

answer

An electrostatic bond is established between the water molecules This bond is called a hydrogen bond the bonds are transitory, but extensive, occurring between each water molecule and an average of between 3 and 4 neighboring molecules at any given time.

question

is solid water less dense than liquid water and why it is important?

answer

Hydrogen Bonding Gives Water Uncommon Stability And results in a number of unusual properties Cohesion - attraction between water molecules

question

definition of heat capacity and the value for water. (Note the units)

answer

The amount of heat input required to raise the temperature of a 1 g of a substance by 1oC. (cal/g·oC) 1.0 for water

question

Why does water have such a high heat capacity relative to other common liquids like alcohol

answer

When heat is added to water, the molecules speed up or vibrate more freely. This disturbs hydrogen bonds, but causes only a small change in temperature, because much of the heat energy is used to break or disrupt the hydrogen bonds 1.0 for water

question

how heat capacity impacts body temperature.

answer

Extensive Hydrogen Bonding Allows Water to exist as a Liquid at Normal Temperatures And across a wide range in temperatures

question

how heat capacity impacts soil temperature.

answer

Soil temperature largely is controlled by moisture (soil water content) Heat energy is required to break hydrogen bonds between water molecules, and heat is released when hydrogen bonds are formed.

question

why water is relatively slow to evaporate.

answer

The addition of heat to water causes a relatively small change in the temperature of the water, because much of the heat energy is used to disrupt the hydrogen bonds

question

calculate water content on a weight and volume basis.

answer

Volume= Vwater/Vsoil x 100% (1cm^3=1 g) Weight=Moist-Dryweight/dry soil weight X 100%

question

at saturation the volumetric water content = ?

answer

total porosity

question

Know the 2 forces responsible for water movement in soils.

answer

Gravity Capillarity

question

how adhesion and cohesion work together to create capillarity in soils.

answer

Adhesion: attraction of water molecules to a surface Cohesion: attraction of water molecules to each other Spontaneous movement of water into and through pore spaces in soil without the aid of gravity. Capillarity (and gravity) move water in unsaturated soils

question

how pore radius impacts the strength of capillary forces.

answer

pore radius decrease, capillarity increase

question

how soil compaction would influence the strength of capillarity.

answer

A compacted clayey soil will be dominated by small pores spaces Capillary forces will be strong, dominating movement Water will move multi-directionally or A loose, sandy soil will be dominated by large pores spaces Capillary forces will be weak, gravity dominates Water will move mostly downward

question

how porosity differences due to structure would exert different capillary forces on water.

answer

Total porosity does not necessarily indicate pore size or the strength of capillary forces

question

how water content influences capillary forces

answer

At saturation, all the pores are filled and capillary forces are satisfied.

question

the definition of potential energy.

answer

Energy waiting to be used or exploited

question

gravitational potential energy and how it is not impacted by soil properties. Know that the choice of a reference point for determining gravitational potential up to you.

answer

The greater the height, the greater the gravitational potential energy. . Units are centimeters of height above a chosen reference level. Gravitational potential energy is due only to the height of an object (water) above a reference point. The higher the elevation the greater the energy.

question

where capillary potential energy originates and how pore size influences capillary potential energy.

answer

Matric/Suction Potential Energy) Applies to unsaturated soils Relates to the ability or potential of soils to move water into pores without gravity In a saturated soil, this quantity would be zero, since all the pores are filled. Therefore, quantification of matric potential energy will apply to unsaturated soils.

question

unsaturated soil, the capillary potential is negative?

answer

yes.

question

pressure potential and the conditions that create it.

answer

Equal to the distance below a free water surface In soils, submergence potential is measured based on the depth below a water table. The soil in this case is saturated and will exert a pressure downward, forcing water through the pore spaces below resulting in flow. In this case the pressure is positive rather than negative as is the case for matric potential which is operating in the capillary fringe, drawing water above the water table.

question

generally which force, gravity or capillarity will dominate water flow under different moisture conditions.

answer

it is the total potential energy of soil water which determines flow. The total potential at any point, therefore, is simply the sum of the three component potentials. If a difference in total potential energy between two points in a soil volume exists, water will tend to flow between them, from high total potential to low total potential.

question

calculate total potential energy at a given point in a soil given the appropriate parameters.

answer

Total Potential Energy=Ψg +Ψm + Ψp

question

what is meant by plant available water

answer

Plant Available Water = Field Capacity - PWP (Water content of soil after drainage from saturation by gravity -Water can no longer be accessed by plants )

question

overall impact of soil texture, density and structure on capillarity.

answer

...

question

Know how to determine if water will flow between two points in a soil and the direction of flow.

answer

Water will always flow from areas of high total potential to low total potential. to do this: Sum the individual potentials at each point Determine if there is a difference in potential between points

question

what a gradient is and how to calculate it. Know that the greater the gradient, the stronger the driving force for water movement.

answer

The driving force for water flow. The difference in total potential divided by the Distance between the two points considered

question

water moves in response to differences in TOTAL potential, not just one potential?

answer

true, The stronger the gradient, the greater the driving force for water movement

question

hydraulic conductivity, what it is, how it is affected by soil physical properties.?

answer

The ease with which water moves through soils Texture Density Structure Water content

question

how hydraulic conductivity is impacted by soil physical properties and water content.

answer

The ease with which water moves through soils Maximum conductivity is under saturated conditions cm/hr

question

how to combine hydraulic conductivity and the gradient to determine overall flow of water in soils. Note the units of flow.

answer

Hydraulic conductivity is determined by measuring the volume of flow through a cross sectional area of soil per unit time Darcy's Equation: Q = K * gradient in cm/hr

question

10YR 5/10

answer

hvc, color in middle of hue yellow-red, 5 medium value(lightness), chroma of 10

question

gravitational potential energy

answer

independent of soil properties due only to the height of an object (water) above a reference point. The higher the elevation the greater the energy. Units are centimeters of height above a chosen reference level.

question

Capillary Potential Energy

answer

Applies to unsaturated soils Relates to the ability or potential of soils to move water into pores matric and Suction Potential

question

capillary pot energy in saturated soils

answer

. In a saturated soil, this quantity would be zero, since all the pores are filled

question

Soil Texture and Matric Potential

answer

Fine-textured soils generally exert stronger capillary forces than do coarse-textured soils because pore sizes are smaller.

question

total potential engergy

answer

Total Potential is the Sum of the Gravitational, Matric, and Pressure Potentials Water moves in response to differences in total potential energy between two points

question

units of potnetial

answer

cm of water

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