Soils Final Exam
Organic soils contain __________% or more organic matter.
20
Highest porosity and lowest bulk density
Clay
Operating all equipment across the slope.
Contour tillage
The study of soil formation
Pedology and soil genesis
The behavior of water in the soil
Soil-water potential
Uses alternating bands of different crops across a slope.
Strip cropping
The hydrologic cycle is fueled by:
Sun
Which of the following has the greatest impact on infiltration?
Surface soil texture
A series of low ridges and shallow channels running across a slope
Terraces
The most fundamental soil property that influences other soil traits is
Texture
Conversion of dry grasslands to desert
Desertification
Twenty five percent of an Ideal soils volume is solid material
False
USDA has 14 textural classes.
False
Which one of the following does drainage achieve?
Make otherwise difficult soil productive
Equal amounts of air and water are ideal for plant growth.
True
Frost wedging occurs when water freezes and expands in rocks or in cracks in rock, causing it to break apart.
True
Gravel or stone bigger than 2 mm are not part of the soil texture.
True
Loess soils are made up of wind-deposited silt and are important agricultural soils in much of iowa, illinois, and neighboring states.
True
Most crop plants require very large amounts of water.
True
Most of the earth's water is in its oceans.
True
Old soils tend to have more distinct soil horizons than young soils.
True
Slope aspect refers to degree of incline
True
Soil is considered a nonrenewable resource within the time frame of a human generation
True
Soil scientists divide mineral particles into size groups called soil separates.
True
Soil supplies anchorage, water, oxygen, and nutrients to plants.
True
Tilth is a term for physical condition of tilled soil.
True
Two important features of topography are slope and aspect.
True
Wet, moist, and dry are descriptive terms for soil consistence moisture levels.
True
When soil becomes too dry for plants to access water, it has reached the permanent wilting point.
True
Soil is a medium for plant growth because it provides water, oxygen, nutrients and ___________?
anchorage
Sand
large particles
The Earth consists of core, mantle, atmosphere, and
crust
What textural class has the largest potential available water
silt loam
Clay
small particles, many small pores, consisting mostly of sheet like particles
What increases as a soil's clay content increases
surface area
Runoff
water that flows over the ground surface rather than soaking into the ground
The main culprit(s) of weathering of soil.
weather and plants
Minerals dissolve in water
Dissolution
Residual soils form from materials transported by gravity
False
Saturation of soil occurs when most soil pores are occupied by water
False
Soil temp is fairly static and not subjected to the influence of many factors.
False
Texture in large areas can be modified easy
False
Topography changes soil formation by changing water movement and soil temperature.
False
Held so tightly to soil particles that it can only be removed by drying soil in an oven
Hygroscopic water
A pedon is a human device for studying soil. It is a section of soil 1 meter x 1 meter x ______ meter.
1 meter
Topsoil;organic matter accumulates; dark colored
A Horizon
Another name for macropore
Aeration pores
In a permeable soil, what will move through easy
Air, roots, water
The C horizon.
All of the above
Parent materials were carried and deposited in moving fresh water to form sediments.
Alluvial soil
Of the following, which is not a way climate affects soil development?
Amount of sedimentary rock in parent material
Which is not true of wetlands?
Are self contained and have no effect on groundwater
Water around sol particles that is so tightly it cannot move; cannot be removed by roots
Available roots
A horizon that contains illuviated clay is the ______ horizon.
B
Subsoil; "zone of accumulates; dark colored
B Horizon
Phosphorus transport from afield can be reduced by
Buffer Strips
Result from reduced iron compounds
Bluish-grey
Underlying hard bedrock; may be cracked, fractured; intrudes into soil
C Horizon
The process of storing carbon in soils, plants, or elsewhere
Carbon Sequestration
Clings loosely to soil particles; can be used by roots
Cohesion water
Transported parent material moved by gravity
Colluvial
Which does not belong in a list of ways in which soil texture affects growing plants
Color
Two ways to improve water-holding capacity of sandy soils.
Conservational tillage and cover crops
What site is likely to have a soil with the highest organic matter?
Cool, moist climate
Result in high levels of organic matter
Dark brown to black
Greatest eluvation; depleted in clay, chemicals, organic matter, light colored
E Horizon
Deposit in a soil horizon, of materials (clay & organic matter) transported from a higher soil layer (A horizon) by leaching of water.
Eluviation
Soil losses of clay, organic matter, and other materials in downward moving water
Eluviation
Soil parent materials carried by wind.
Eolian deposit
The total water loss from transpiration and evaporation is called:
Evapotranspiration
Most of the earths surface is suitable for growing crops
False
Most of the land in the United States is used to grow cultivated crops.
False
Chemical weathering is the disintegration of rock by temperature and wind.
False
Colluvium is moved by glaciers.
False
Furrows with small ridges across them
Furrow diking
Debris dropped in place to form deposits during ice melting.
Glacial till
Which is not affected by soil temps
Gleying
What structure would be a good seed bed
Granular
Drains away under the force of gravity
Gravitational potential
Flows downward through the soil profile
Gravitational water
Minerals react with the hydrogen in water molecules and split water
Hydrolysis
Water molecules join with the crystalline structure of minerals
Hydration
Phosphorus is transported by _________ from fields.
Leaching
Result from oxidized iron minerals
Light brown, yellow to red
Large spaces in soil that are responsible for movement of air and water in soil.
Macropores
The attraction of water to soil particles and to itself
Matric potential
Which of the following pollutants is in water, is not generally attributed to agriculture?
Mercury
Smaller spaces in soil that retain water for plant use
Micropores
Are dissolved in water and move toward roots through water.
Nutrient availability
Wholly or partially decayed plant and animal debris; undisturbed soil; example-forest
O Horizon
Derived from the amount of dissolved soil salts
Osmotic potential
Chemical reaction in which an element loses electrons to another participant in the reaction, often oxygen.
Oxidation-Reduction
Which is not a problem created by modern drainage systems?
Ponding
Open spaces of voids between solid particles of mineral and organic mater in soil.
Pore space
Which environment generates the most organic matter in soil due to the extensive, fibrous root systems of the native vegetation?
Prairie
Which of the following increases soil water storage?
Precipitation
Rapid water movement downward in large pores after a rain is called:
Preferential flow
Soils formed in place from the left overs of broken-down bedrock.
Residual soils
The process by which carbon is recycled directly back to the atmosphere by plants and animals
Respiration
Good soil structure in the subsoil imprives
Root elongation
Form of physical weathering
Root wedging
Rock formed by pressure applied to lose materials is called ___________.
Sedimentary
Ribbon test of a loamy sand would be:
Shorter than 1 inch
The arrangement of solid particles and pore space.
Soil Matrix
Loss of soil quality
Soil degradation
The A, B, and E (if it exists) are referred to as true soil or the _________.
Solum
Where chemical reactions occur in the plant.
Solvent
Evaporation of water to cool the plant
Transpiration
The four soil-forming processes do not include which of the following:
Transpiration
A shortage of water on a plant is said to stress it.
True
A soil will become anaerobic when excess moisture displaces air from soil pores.
True
Adhesion is the attraction of soil water to soil particles
True
Agricultural fertilizer runoff is an example of a non-point source of water pollution.
True
Buffer strips and stubble mulching are practices used to capture snowfall.
True
Capillary action is the action of water moving upward in the soil as the surface layers dry.
True
Internal tension keeps plant tissue stiff, upright, and expanded to receive sunlight.
Turgidity
Plant tissue is 50 to 90% water
Water content
Roots growing into a crack in rock is called root _________.
Wedging
What best defines particle density
What soil should weigh, Density of soil particles
May indicate that chemicals have leached out or may be due to accumulations of lime, gypsum, or other salts
White to light grey
Loam
a soil in which sand, silt, and clay contribute equally to the soil's properties.
Tile drain spacing is smallest for a ______ soil.
clay loam
Excessive soil moisture generally __________ nutrient uptake
decreases
Limited soil moisture generally ___________ nutrient uptake
decreases
Four consequences of poorly drained soil.
denitrification, delays planting, can cause accumulation of salts in root zones,
Maximum plant available water is ____________ minus _____________.
field capacity, gravitational water
bulk density
mass of a volume of undisturbed dry soil
Permability
measure of rate of water movement through soil
Silt
medium-size soil particles, silky or powdery to the touch
Patches of different colors that suggest the soil is waterlogged for part of the year
mottled
Runoff decreases as _________________ increases
preferential flow
Soil temperature is critical to the grower because it effects all of the following except
soil texture
The three-phase system used to describe soil is
solids, liquids, and gas
