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