soils

laterite

A third important type of soil is laterite. Laterite forms in tropical areas. Temperatures are warm and rain falls every day (Figure 9.12). So much rain falls that chemical weathering is intense. All soluble minerals are washed from the soil. Plant nutrients get leached or carried away. There is practically no humus. Laterite soils are often red in color from the iron oxides. If laterites are exposed to the Sun, they bake as hard as a brick.

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topsoil

The first horizon is the A horizon. It is more commonly called the topsoil. The topsoil is usually the darkest layer of the soil. It is the layer with the most organic material. Humus forms from all the plant and animal debris that falls to or grows on the ground. The topsoil is also the region with the most biological activity. Many organisms live within this layer. Plant roots stretch down into this layer. The roots help to hold the topsoil in place. Topsoil usually does not have very small particles like clay. Clay-sized particles are carried to lower layers as water seeps down into the ground. Many minerals dissolve in the fresh water that moves through the topsoil. These minerals are carried down to the lower layers of soil.

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soil conservation

Soil is a renewable resource. But it is only renewable if we take care of it. Natural events can degrade soil. These events include droughts, floods, insect plagues, or diseases that damage soil ecosystems. Human activities can also degrade soil. There are many ways in which people neglect or abuse this important resource.

subsoil

Below the topsoil is the B horizon. This is also called the subsoil. Soluble minerals and clays accumulate in the subsoil. Because it has less organic material, this layer is lighter brown in color than topsoil. It also holds more water due to the presence of iron and clay. There is less organic material in this layer.

pedalfer

One important type of soil forms in a deciduous forest. In these forests, trees lose their leaves each winter. Deciduous trees need lots of rain at least 65 cm of rainfall per year. Deciduous forests are common in the temperate, eastern United States. The type of soil found in a deciduous forest is a pedalfer (Figure 9.10). This type of soil is usually dark brown or black in color and very fertile.

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time

Soil formation increases with time. The longer the amount of time that soil remains in a particular area, the greater the degree of alteration. The warmer the temperatures, the more rainfall, and the greater the amount of time, the thicker the soils will become.

climate

Climate is the most important factor in soil formation. The climate of a region is the result of its temperature and rainfall. We can identify different climates by the plants that grow there (Figure 9.6). Given enough time, a climate will produce a particular type of soil. The original rock type does not matter. The same rock type will form a different soil type in each different climate. Rainfall Rainfall in an area is important because it influences the rate of weathering. More rain means that more rainwater passes through the soil. The rainwater reacts chemically with the particles. The top layers of soil are in contact with the freshest water, so reactions are greatest there. High rainfall increases the amount of rock that experiences chemical reactions. High rainfall may also carry material away. This means that new surfaces are exposed. This increases the rate of weathering. Temperature The temperature of a region is the other important part of climate. The rate of chemical reactions increases with higher temperatures. The rate doubles for every 10 C increase in temperature. Plants and bacteria grow and multiply faster in warmer areas.

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biological activity

Biological activity produces the organic material in soil. Humus forms from the remains of plants and animals. It is an extremely important part of the soil. Humus coats the mineral grains. It binds them together into clumps that hold the soil together. This gives the soil its structure. Soils with high humus are better able to hold water. Soils rich with organic materials hold nutrients better and are more fertile. These soils are more easily farmed. The color of soil indicates its fertility. Black or dark brown soils are rich in nitrogen and contain a high percentage of organic materials. Soils that are nitrogen poor and low in organic material might be gray, yellow, or red.

parent rock

The original rock is the source of the inorganic portion of the soil. Mechanical weathering breaks rock into smaller pieces. Chemical reactions change the rocks minerals. A transported soil forms from materials brought in from somewhere else. These soils form from sediments that were transported into the area and deposited. The rate of soil formation is faster for transported materials because they have already been weathered. A soil is a residual soil when it forms in place. Only about one third of the soils in the United States form this way. The material comes from the underlying bedrock. Residual soils form over many years since it takes a long time for solid rock to become soil. First, cracks break up the bedrock. This may happen due to ice wedging. Weathering breaks up the rock even more. Then plants, such as lichens or grasses, become established. They cause further weathering. As more time passes and more layers of material weather, the soil develops.

chorizon

The next layer down is the C horizon. This layer is made of partially altered bedrock. There is evidence of weathering in this layer. Still, it is possible to identify the original rock type from which this soil formed (Figure Not all climate regions develop soils. Arid regions are poor at soil development. Not all regions develop the same soil horizons. Some areas develop as many as five or six distinct layers. Others develop only a few.

types of soils

For soil scientists, there are thousands of types of soil! Soil scientists put soils into very specific groups with certain characteristics. Each soil type has its own name. Lets consider a much simpler model, with just three types of soil. These types are based on climate. Just remember that there are many more than just these three types.

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soil formation

Soil formation requires weathering. Where there is less weathering, soils are thinner. However, soluble minerals may be present. Where there is intense weathering, soils may be thick. Minerals and nutrients would have been washed out. Soil development takes a very long time. It may take hundreds or even thousands of years to form the fertile upper layer of soil. Soil scientists estimate that in the very best soil forming conditions, soil forms at a rate of about 1mm/year. In poor conditions, it may take thousands of years! How well soil forms and what type of soil forms depends on many factors. These include climate, the original rock type, the slope, the amount of time, and biological activity.

characteristics and importance of soil

We can think about soil as a living resource. Soil is an ecosystem all by itself! Soil is a complex mixture of different materials. Some of them are inorganic. Inorganic materials are made from non-living substances like pebbles and sand. Soil also contains bits of organic materials from plants and animals. In general, about half of the soil is made of pieces of rock and minerals. The other half is organic materials. In the spaces of soil are millions of living organisms. These include earthworms, ants, bacteria, and fungi. In some soils, the organic portion is entirely missing. This is true of desert sand. At the other extreme, a soil may be completely organic. Peat, found in a bog or swamp, is totally organic soil. Organic materials are necessary for a soil to be fertile. The organic portion provides the nutrients needed for strong plant growth.

pedocal

Pedocal soil forms where grasses and brush are common (Figure 9.11). The climate is drier, with less than 65 cm of rain per year. With less rain, there is less chemical weathering. There is less organic material and the soils are slightly less fertile.

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soil horizons and profiles

Soil develops over time and forms soil horizons. Soil horizons are different layers of soil with depth. The most weathering occurs in the top layer. This layer is most exposed to weather! It is where fresh water comes into contact with the soil. Each layer lower is weathered just a little bit less than the layer above. As water moves down through the layers, it is able to do less work to change the soil. If you dig a deep hole in the ground, you may see each of the different layers of soil. All together, the layers are a soil profile. Each horizon has its own set of characteristics (Figure 9.8). In the simplest soil profile, a soil has three horizons.

soil texture

The inorganic part of soil is made of different amounts of different size particles. This affects the characteristics of a soil. Water flows through soil more easily if the spaces between the particles are large enough and well connected. Sandy or silty soils are light soils because they drain water. Soils rich in clay are heavier. Clay particles allow only very small spaces between them, so clay-rich soils tend to hold water. Clay-rich soils are heavier and hold together more tightly. A soil that contains a mixture of grain sizes is called a loam. Soil scientists measure the percentage of sand, silt, and clay in soil. They plot this information on a triangular diagram, with each type of particle at one corner (Figure 9.7). The soil type is determined by where the soil falls on the diagram. At the top, the soil is clay rich. On the left corner, the soil is sandy. On the right corner, the soil is silty.

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harmful practices

People remove a lot of vegetation. They log forests or prepare the land for farming or construction. Even just walking or riding your bike over the same place can kill the grass. But plants help to hold the soil in place (Figure faster than it is forming. In these locations, soil is a non-renewable resource. Soils may also remain in place but become degraded. Soil is contaminated if too much salt accumulates. Soil can also be contaminated by pollutants.

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protecting soil

There are many ways to protect soil. We can add organic material like manure or compost. This increases the soils fertility. Increased fertility improves the soils ability to hold water and nutrients. Inorganic fertilizers also increase fertility. These fertilizers are less expensive than natural fertilizers, but they do not provide the same long term benefits. Careful farming helps to keep up soil quality each season. One way is to plant different crops each year. Another is to alternate the crops planted in each row of the field. These techniques preserve and replenish soil nutrients. Planting nutrient rich cover crops helps the soil. Planting trees as windbreaks, plowing along contours of a field, or building terraces into steeper slopes all help to hold soil in place (Figure 9.14). No-till or low-till farming disturbs the ground as little as possible during planting.

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instructional diagrams

description_image

This diagram shows that of the soil horizon. There are many types of soils, and each one has unique characteristics, like color, texture, structure, and mineral content. The depth of the soil also varies. The kind of soil in an area helps determines what type of plants can grow. Soil is made up of distinct horizontal layers; these layers are called horizons. They range from rich, organic upper layers (humus and topsoil) to underlying rocky layers (subsoil, regolith and bedrock). O Horizon-The top, organic layer of soil, made up mostly of leaf litter and humus (decomposed organic matter). A Horizon-The layer called topsoil; it is found below the O horizon and above the E horizon. Seeds germinate and plant roots grow in this dark-colored layer. It is made up of humus (decomposed organic matter) mixed with mineral particles. E Horizon-This eluviation (leaching) layer is light; this layer is beneath the Horizon and above the B Horizon. It is made up mostly of sand and silt, having lost most of its minerals and clay as water drips through the soil. B Horizon-Also called the subsoil-this layer is beneath the E Horizon and above the C Horizon. It contains clay and mineral deposits (like iron, aluminum oxides, and calcium carbonate) that it receives from layers above it when mineralized water drips from the soil above. C Horizon-Also called regolith: the layer beneath the B Horizon and above the R Horizon. It consists of slightly broken-up bedrock. Plant roots do not penetrate into this layer; very little organic material is found in this layer. R Horizon-The unweathered rock (bedrock) layer that is beneath all the other layers.

description_image

This diagram depicts the layers of the Earth. The top layer is the O Horizon. This is the humus that is the surface litter, decomposing plant matter. Below that is the Horizon which is the topsoil. It is mixed humus and leached mineral soil. Below that is the E Horizon which is the zone of leaching. There is less humus and the minerals are resistant to leaching. Below that is the B Horizon. This is the subsoil that is an accumulation of leached minerals like iron and aluminum oxides. The final layer is the C Horizon. It is the weathered parent material that is partly broken-down minerals.

description_image

The figure shows the different horizons and profiles of soil. The A-horizon is also called topsoil. This is the layer of soil where plants grow. Many small animals such as insects and worms also live here. Topsoil is rich in nutrients from decomposed plants and animals. Right under the A-horizon is the B-horizon, or the subsoil. If a plant has very deep roots, these roots may reach the subsoil. Subsoil contains very little organic matter. However, because of accumulated minerals such clay and iron, it holds more water than topsoil. Beneath the B-horizon is the C-horizon or substratum. The C-horizon is mostly composed of particles of bedrock, sediment, and other geologic materials.

questions

Factors that influence soil formation in a region include

a. average temperature.

b. amount of rainfall.

c. type of bedrock.

-->  d. all of the above

Topsoil is dark in color because it

a. undergoes a lot of chemical weathering

-->  b. has a large amount of organic material

c. is full of dark rocks

d. contains a lot of worms

How does humus affect soil?

a. It prevents soil from holding water.

-->  b. It binds together mineral particles in soil.

c. It reduces the nitrogen content of soil.

d. It makes soil less fertile for plant growth.

In the eastern U.S., high rainfall and deciduous forests have soils called

a. pedocal

b. laterite

-->  c. pedalfers

d. weathered soil

Which size of rock particles in soil causes soil to hold the most water?

a. gravel

-->  b. clay

c. sand

d. silt

Adding organic material to soil

-->  a. allows it to contain water and nutrients

b. decreases its fertility

c. increases its A horizon

d. often kills existing vegetation

Farmers terrace hillsides to

a. eliminate the soils C horizon

b. increase the types of crops they can grow

c. increase the creation of soil

-->  d. reduce erosion

Which soil horizon is usually darkest in color?

-->  a. A

b. B

c. C

d. D

What type of soil is usually the most fertile?

-->  a. pedalfer

b. pedocal

c. laterite

d. subsoil

Soil made from the bedrock that lies beneath it is

a. transported soil

b. eroded soil

-->  c. residual soil

d. weathered soil

A soil sample is red in color and contains almost no humus or soluble minerals. Which type of soil is it most likely to be?

a. pedalfer

b. pedocal

-->  c. laterite

d. none of the above

Practices that help to conserve soil include

a. cutting down trees.

-->  b. building terraces on steep slopes.

c. planting the same crops every year.

d. two of the above

Without weathering, Earth would have no soils.

-->  a. true

b. false

Most soils consist only of small rock particles and minerals.

a. true

-->  b. false

The average rate of soil formation is about 1 cm/year.

a. true

-->  b. false

Flat lands develop thicker soils than steeper slopes.

-->  a. true

b. false

Dry conditions produce the thickest soils.

a. true

-->  b. false

Rainforests are rich ecosystems and their soils are rich in nutrients.

a. true

-->  b. false

The majority of soils in the U.S. are transported soils.

-->  a. true

b. false

Most topsoil consists mainly of clay-sized rock particles.

a. true

-->  b. false

All soils contain organic material.

a. true

-->  b. false

The B horizon contains more organic material than the C horizon.

-->  a. true

b. false

Chemical erosion is most common in deserts.

a. true

-->  b. false

Pedocal soils form in regions covered with grasslands and brush.

-->  a. true

b. false

Dead leaves from deciduous trees enrich laterite soils each year.

a. true

-->  b. false

Adding manure to soil reduces the amount of water the soil can hold.

a. true

-->  b. false

No-till farming helps to conserve topsoil.

-->  a. true

b. false

common name for soil horizon B

a. humus

b. laterite

c. topsoil

d. pedocal

-->  e. subsoil

f. soil profile

g. pedalfer

type of soil found in grasslands

a. humus

b. laterite

c. topsoil

-->  d. pedocal

e. subsoil

f. soil profile

g. pedalfer

common name for soil horizon A

a. humus

b. laterite

-->  c. topsoil

d. pedocal

e. subsoil

f. soil profile

g. pedalfer

type of soil found in tropical areas

a. humus

-->  b. laterite

c. topsoil

d. pedocal

e. subsoil

f. soil profile

g. pedalfer

organic material in soil

-->  a. humus

b. laterite

c. topsoil

d. pedocal

e. subsoil

f. soil profile

g. pedalfer

type of soil found in deciduous forests

a. humus

b. laterite

c. topsoil

d. pedocal

e. subsoil

f. soil profile

-->  g. pedalfer

all the layers of a particular soil

a. humus

b. laterite

c. topsoil

d. pedocal

e. subsoil

-->  f. soil profile

g. pedalfer

diagram questions

question_image

What is between the B horizon and the Bedrock?

a. A horizon

-->  b. C horizon

c. D horizon

d. E horizon

question_image

What is the deepest layer in the diagram?

a. B-horizon

b. A-horizon

c. C-horizon

-->  d. Bedrock

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How many horizons are there before bedrock?

a. 2

-->  b. 3

c. 4

d. 1

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How many layers of soil are shown in the diagram?

a. 3

-->  b. 4

c. 5

d. 1

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What will happen with plant life if there was just the Bedrock level?

-->  a. There would be no plants.

b. Some plants would grow.

c. The plants would go taller.

d. Plants would thrive.

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Identify the layer of soil that has the most biological activity.

a. Sub Soil

b. Bedrock

-->  c. Top Soil

d. Parent material

question_image

What is between the bedrock and the top soil?

-->  a. The sub soil and the parent material

b. Only the parent material

c. The organic layer

d. Only the sub soil

question_image

What layer of soil is below parent material?

a. Top soil

-->  b. Bedrock

c. Organic layer

d. Sub soil

question_image

How many layers are there beneath the organic layer of a plant?

a. 6

b. 3

c. 5

-->  d. 4

question_image

How many layers are there in the soil?

a. 4

-->  b. 5

c. 3

d. 7

question_image

What layer is directly below the topsoil?

-->  a. sub soil

b. parent material

c. flintstones

d. bedrock

question_image

Which is the lowest level of the soil?

a. Subsoil

b. Organic Layer

c. Parent Material

-->  d. Bedrock

question_image

What lies below the ground level?

a. bedrock

-->  b. topsoil

c. parent material

d. subsoil

question_image

This is usually the darkest layer of the soil. It is the layer with the most organic material.

a. Subsoil

b. Parent material

c. Bedrock

-->  d. Topsoil

question_image

What is the bottom level of soil?

a. topsoil

b. weathered

c. subsoil

-->  d. bedrock

question_image

Which level does a worm live?

a. Bedrock

b. Weathered parent material

-->  c. Subsoil

d. Ground level

question_image

How many layers are below the subsoil?

a. 1

b. 4

c. 3

-->  d. 2

question_image

How many layers of soil are present between the bedrock and ground level?

a. One

b. Two

c. Five

-->  d. Three

question_image

Which among the layers contains enormous rock formations?

a. Ground Level

b. Subsoil

c. Weathered Parent Material

-->  d. Bedrock

question_image

In which layer of soil does vegetation take root?

a. bedrock

b. subsoil

c. weathered rock fragments

-->  d. humus

question_image

Which layer has the most organic material?

a. B-horizon

b. O-horizon

c. C-horizon

-->  d. A-horizon

question_image

What layer is most likely made up of organic components due to decomposition of leaves and other plant materials.

a. Topsoil

b. Bedrock

-->  c. Humus

d. Subsoil

question_image

Which soil level contains the most nutrients for plants?

-->  a. Humus

b. Subsoil

c. Weathered rock fragments

d. Bedrock

question_image

How many horizons does the soil have?

a. 3

b. 6

c. 4

-->  d. 5

question_image

How many layers of soil are below the topsoil?

-->  a. 3

b. 2

c. 0

d. 1

question_image

What is the uppermost layer of the soil called?

a. bedrock

-->  b. humus

c. subsoil

d. topsoil

question_image

What is the layer with the most organic material?

a. B (subsoil)

b. C (parent material)

-->  c. A (topsoil)

d. E (eluviated horizon)

question_image

What is the deepest level of the soil?

-->  a. bedrock

b. eluviated horizon

c. subsoil

d. humus or organic

question_image

Which layer is directly above the subsoil?

-->  a. Eluviated horizon

b. Parent Material

c. Humus

d. Bedrock

question_image

Which part of the earth's structure precedes the subsoil, from the surface to the nucleus?

-->  a. Eluviated Horizon

b. Humus

c. Bedrock

d. Topsoil

question_image

How many layers are there to the soil?

a. 4

b. 7

c. 5

-->  d. 6

question_image

What is the lithographed rock that lies under the loose softer material at the surface of the Earth or other terrestrial planet?

a. A

b. E

c. O

-->  d. R

question_image

Which layer of soil is between the subsoil and bedrock?

a. Eluviated Horizon

b. Topsoil

c. Humus

-->  d. Parent Material

question_image

What is the name of the surface litter?

a. E horizon

b. B horizon

c. A horizon

-->  d. O horizon

question_image

What is the lowermost layer of soil called?

a. E horizon

b. A horizon

c. O horizon

-->  d. Bedrock

question_image

What lies above the bed rock?

-->  a. parent material

b. subsoil

c. topsoil

d. surface litter

question_image

How many layers are present in Soil?

a. 7

b. 6

-->  c. 5

d. 4

question_image

How many layers are there in the soil?

a. 3

b. 2

-->  c. 5

d. 4

question_image

What is the topmost layer among these?

-->  a. O horizon

b. B horizon

c. E horizon

d. C horizon

question_image

Which is the most recent layer in the diagram?

a. Bedrock

b. C horizon

-->  c. O horizon

d. A horizon

question_image

From the diagram, identify which horizon is also known as topsoil.

-->  a. A horizon

b. O horizon

c. E horizon

d. R horizon

question_image

What lies in between the R horizon and B horizon?

a. E horizon

b. A horizon

-->  c. C horizon

d. O horizon

question_image

How many horizons make up the soil layer?

-->  a. 3

b. 1

c. 2

d. 4

question_image

How many layers does the regolith have?

a. 7

b. 4

c. 6

-->  d. 5

question_image

Arrange the following layers of soil in increasing levels or porosity?

a. O horizon < E horizon < B horizon  < R horizon

b. R horizon  < O horizon < B horizon  < E horizon

-->  c. R horizon < B horizon < E horizon < O horizon

d. B horizon < E horizon < O horizon < R horizon

question_image

What is the topmost layer of the soil called?

a. E horizon

-->  b. O horizon

c. B horizon

d. A horizon

question_image

Which part is labelled with middle horizon?

-->  a. B

b. Bedrock

c. A

d. C

question_image

What is the top layer of the soil profile?

a. Bedrock

-->  b. A-Horizon

c. B-Horizon

d. C-Horizon

question_image

Which horizon contains the most organic material?

a. B-Horizon

b. Bedrock

c. C-Horizon

-->  d. A

question_image

How many horizons of soil are present above the bedrock?

a. Two

-->  b. Three

c. Four

d. One

question_image

How many layers of soil?

a. 1

b. 3

-->  c. 4

d. 2

question_image

Which layer has unconsolidated parent material?

a. E horizon

-->  b. C horizon

c. B horizon

d. R horizon

question_image

This layer is made of partially altered bedrock.

-->  a. C horizon

b. R horizon

c. B horizon

d. O horizon

question_image

How many layers are there between the O horizon and B horizon?

-->  a. 2

b. 5

c. 1

d. 3

question_image

What is the layer directly below the O horizon?

a. B horizon

b. E horizon

c. C horizon

-->  d. A horizon

question_image

How many soil horizons are beneath the grass in this image?

a. 5

b. 7

c. 8

-->  d. 6

question_image

The subsoil which contains clay and mineral deposits consists of how many horizons/s?

a. 3

b. 2

c. 4

-->  d. 1

question_image

The horizon indicated in the picture is otherwise known as:

a. Bedrock

b. Pedalfer

c. Subsoil

-->  d. Topsoil

question_image

Topsoil is located in which horizon?

a. B

b. R

c. C

-->  d. A

question_image

Which horizon is located the furthest away from the surface of the ground?

a. O

b. A

c. B

-->  d. R

question_image

How many horizons are there in the diagram?

a. 3

b. 2

c. 4

-->  d. 5

question_image

What is the uppermost layer of the soil called?

a. B Horizon

-->  b. O Horizon

c. A Horizon

d. C Horizon

question_image

Which horizon is in the bottom part of the soil?

a. B Horizon

b. A Horizon

c. O Horizon

-->  d. R Horizon

question_image

Which layer represents the zone of accumulation?

-->  a. B

b. E

c. O

d. A

question_image

What is the layer of soil, just beneath the top soil, from which soluble nutrients are removed by water?

a. Parent rock

b. Weathered

-->  c. Zone of leaching

d. Zone of accumulation

question_image

How many layers are shown in the diagram?

-->  a. 6

b. 4

c. 5

d. 7

question_image

How many soil horizons are in the diagram?

-->  a. 6

b. 4

c. 5

d. 3

question_image

What is directly underneath the zone of leaching?

-->  a. zone of accumulation

b. bedrock

c. flintstones

d. weathered

question_image

Why is soil an important resource?

a. Climate is the most important factor in determining the type of soil that forms in a particular area.

-->  b. Soil is a complex mixture of different materials. Some of them are inorganic. Inorganic materials are made from non-living substances like pebbles and sand. Soil also contains bits of organic materials from plants and animals.

c. Plants and animals source their nutrients from the soil and it is home to many different forms of life.

d. Soil formation increases with time.

question_image

What layer is directly below the topsoil?

-->  a. subsoil

b. surface layers

c. bedrock

d. parent material

question_image

Which of the following layers comprises mineral particles?

a. bedrock

b. subsoil

c. surface layers

-->  d. Topsoil

question_image

What lies above the bedrock?

a. subsoil

-->  b. parent material

c. surface layers

d. topsoil

question_image

Which layer contains the most organic material?

a. Bedrock

b. Subsoil

-->  c. Topsoil

d. Parent material

question_image

How many layers are under the surface layers of the ground?

a. There are 5

b. There are 3

-->  c. There are 4

d. There are 6

question_image

This horizon contains mineral particles mixed with organic material.

-->  a. A horizon

b. O horizon

c. B horizon

d. C horizon

question_image

By what label is the topsoil referred to in the diagram?

-->  a. A

b. E

c. B

d. O

question_image

What lies between C and E in diagram below?

a. A

b. S

c. O

-->  d. B

question_image

How many layers does the zone of leaching have?

a. 5

-->  b. 3

c. 1

d. 4

question_image

What layer is between the subsoil and topsoil?

-->  a. transition

b. A horizon

c. O horizon

d. bedrock

question_image

Identify the layer of soil closest to the surface.

-->  a. Topsoil

b. Basement

c. Parent Material

d. Subsoil

question_image

What is underneath the subsoil?

a. topsoil

b. surface soil

-->  c. parent material

d. surface

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What lies above the C horizon in the diagram?

a. O horizon

-->  b. B horizon

c. A horizon

d. L horizon

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Which of the following layers has two sub-horizons?

-->  a. Parent material

b. Surface

c. Surface Soil

d. Subsoil

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A general soil profile consists of how many layers?

-->  a. 3

b. 5

c. 2

d. 4

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How many layers are beneath the surface?

a. 4

b. 2

-->  c. 3

d. 1

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How many sub-horizons are there?

a. 2

b. 3

c. 5

-->  d. 4

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What happens if topsoil is destroyed or swept away by erosion?

a. Plants will grow faster.

b. More plants will grow.

-->  c. Plants cannot grow.

d. Animals will eat the subsoil.

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Which horizon lies below subsoil?

a. Humus

b. Surface

c. Topsoil

-->  d. Parent material

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What is the condition of humus in a wet climate?

a. thick and lush

-->  b. thin or absent

c. dry and present

d. moist and present

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What is found in moist climate?

-->  a. humus and leached soil (quartz and clay minerals present)

b. calcium carbonate pellets and nodules precipitated

c. thin or absent humus

d. thick masses of insoluble iron and aluminum oxides

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For pedalfer, what is between humus and granite?

-->  a. iron and oxides

b. leached soil

c. calcium carbonate pellets

d. iron-rich clays

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What kind of climate produces thin or absent humus?

a. none

-->  b. wet climate

c. dry climate

d. moist climate

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From the diagram, how many kinds of climate are there?

a. 2

-->  b. 3

c. 5

d. 4

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How many types of climate do we know?

a. 1

-->  b. 3

c. 4

d. 2

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How thick is the humus layer in wet climate?

a. overflowing

b. very thick

-->  c. thin or absent

d. same as with moist climate

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In a dry climate, what occurs just below humus and leached soil?

-->  a. Calcium carbonate pellets and nodules precipitated

b. Thin or absent humus

c. Quartz and clay minerals present

d. Iron and aluminum oxides

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What lester labels the transition?

-->  a. e

-->  b. a

c. B

d. o

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Where is the subsoil located?

a. C

-->  b. b

c. e

d. o

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Where is the partially altered parent materials found?

a. B horizon

-->  b. c horizon

c. a horizon

d. o horizon