Let’s Get Down and Dirty!

I

APES

InstructionsYou will need to answer each question on your copy of the PowerPoint provided. Each question is in an orange box. There are 21 questions for this section. You may add extra paper if necessary. You will only be allowed to use your written answers to the questions on the January 27 quiz.

Save yourself time and do not write complete sentences. Some of the questions you should be able to answer without using the resource link.

Look for the following symbol to click to find answers to the questions: Click

Soil is a mixture of eroded rock, mineral nutrients, decaying organic matter, water, air, and living organisms

5 Soil Forming Factors

• Parent material• Climate• Living organisms• Topography• Time

Why does soil form faster in warm wet climate as compared to cooler climates?

What is the role of rhizobia bacteria and mycorrhizae in soil?

Click

Soil texture is an important soil characteristic that drives crop production and field management. The textural class of a soil is

determined by the percentage of sand, silt, and clay.

Soil texture determines the rate at which water drains through a saturated soil; water moves more freely through sandy soils than it does

through clayey soils.

Silty clay – rolls into a ball; dark in color

Why does sand NOT contain nutrients, but silt does?Click

Soil Squeeze Test

Clay soil will hold its shape and when poked it sits stubbornly in your hand

Sandy soil will fall apart easily as you open your hand

Loamy soil will hold its shape and when you give it a light poke it will crumble

Soil permeability is a measurement of the rate water moves through soil. Soil permeability is governed by the makeup of the soil. Sandy and rocky soils have a high rate of soil permeability, while clay types of soils have a low rate. The rate of soil permeability can affect engineering and planning for structures such as sewer systems and earthen dams. It also is used to determine footings in buildings to prevent settling.

Porosity is the open space between soil grains. Soil scientists use porosity measurements to determine how effectively air and water move through the subsurface. Large pore spaces within a soil column help promote infiltration allowing the water to uptake into the root system of plants without mounding and becoming boggy.

Mature soils are arranged in a series of zones called

soil horizons

Most mature soils have at least three of the possible

horizons

In forests you will find the O Horizon (surface litter layer)

Topsoil layer (humus)

Subsoil layer (inorganic matter)

Parent material (inorganic matter)

The A and O Horizons is where the interaction with bacteria, fungi, earthworms, and small worms take place

Fertile soil that produces high crop

yields has a thick topsoil layer with

lots of humus

What are the benefits humus provides soil?Click

Dark brown or black topsoil is nitrogen rich and high in organic matter

Gray, bright yellow, or red topsoil is low in organic matter and needs Nitrogen enrichment

It can take 200 to 1000 years to develop an inch of topsoil

There are 16 elements essential for plant growth. What 3 do plants obtain from air and water? What are the 3 primary macronutrients important for plant growth?

Click

How does soil pH affect soil fertility?

Click

Soil Problems• Acidic soil – decrease uptake of nutrients

• add lime and organic fertilizer

• Alkaline soil -western and southwestern United States• Add sulfur – converted by bacteria to sulfuric acid

• Soil erosion• Sheet erosion• Rill erosion• Gully erosion

Why do farmers add lime to acidic soils? What is the lime made of that helps with this process?

Click

Wind Erosion

Occurs mostly in flat, bare areas; dry, sandy soils; or anywhere the soil is loose, dry, and finely granulated. Wind erosion damages land

and natural vegetation by removing soil from one place and depositing it in another. It causes soil loss, dryness and deterioration

of soil structure, nutrient and productivity loss and air pollution.

Flowing water coalesces into small channels; tiny

gullies form

Rill Erosion

Channels coalesce into larger channels; water increases velocity and volume; erodes into

larger gully

Gully Erosion

Differentiate between wind erosion, rill erosion, gully erosion,

and tillage erosion.Click

Harmful Effects of Soil Erosion

List the negative effects of soil erosion caused by wind and water.

Click

Sediment floating downstream as indicated by the brown color you

see in the estuary

Providence Canyon– Lumpkin, GA

What caused these deep gullies?Click

Global Soil Erosion

• Topsoil is eroding faster than it forms on about one third of the world’s croplands

• 15% of land scattered across the globe are too eroded to grow crops because

• Overgrazing (35%)• Deforestation (30%)• Unsustainable farming (28%)

Global Soil Erosion

• About 40% of world’s land used for agriculture is seriously degraded by

• Erosion• Salinization• Waterlogging

• Soil degradation has reduced food production on about 16% of world’s cropland

What are the two misconceptions about desertification?

What are the causes of desertification?Click

Explain how plants on land help prevent soil erosion?Click

List the 7 ways to prevent soil erosion.Click

Which of the following ecosystems best characterizes a thick O horizon?

A. ChaparralB. DesertC. GrasslandD. Semi-desertE. Taiga

How does soil compaction affect the use of the land?

A. Compacted soils have negligible effects on land use.B. Compacted soils help reduce the threat of invasive

species taking over.C. Although compacted soils reduce the flow of water

through the soil, there is an increase in the availability of oxygen.

D. Soil compaction helps to keep the topsoil from eroding.

E. Compaction reduces space between soil particles, obstructing the flow of gases, nutrients, and water through the soil.

Deforestation, overgrazing, and the overworking of soil for crop production can lead to which of the following>

A. SalinizationB. MonocultureC. DesertificationD. Increased crop rotationE. Depletion of aquifers

Soil Conservation

• Conservation tillage farming (no till)

• Terracing• Contour farming• Strip cropping

• Alley cropping• Gully reclamation• Windbreaks or

shelterbreaks• Land classification

No-till agriculture is designed to avoid soil degradation. Farmers using this method leave crop residues in the field between seasons. The intact roots hold the soil in place, reducing both wind and soil erosion, and the undisturbed soil is able to regenerate natural soil horizons. No-till agriculture also reduces the emissions of CO2 because the intact soil undergoes less oxidation. In many cases, however, in order for no-till agriculture to e successful, farmers must apply herbicides to the fields before, and sometimes after, planting so that weeds do not compete with the crops for nutrients and water.

Examples of No-till Agriculture

Terrace Farming

Terrace farming is commonly found throughout Asia, and is used when the terrain is particularly hilly or steep. Terraces are made using low walls of earth up the side of the hills, these allow the farmers to make flat areas for planting their crops – the terraces. The terraces act in several ways but especially in allowing the soil to remain in place and water flowing down the hill through natural gravity can be moved and channeled through the terrace setup using a system of small openings and gates to allow different areas to be dry or wet at any one time.

Strip Cropping – a row of crop such as corn alternates in strips with another crop, such as grass-legume mixture,

that completely covers the soil (intercropping)

Contour Plowing

Contouring involves plowing, planting, and cultivating sloping

fields around hillsides, with curving furrows horizontal to the hill, instead of furrows running straight uphill and downhill. The curved furrows catch rainfall and allow much of it to soak into the ground. They also catch soil

washing down hill

Combined with strip cropping

Alley cropping or hedgerow intercropping is an agroforestry practice in which perennial, preferably

leguminous trees or shrubs are grown simultaneously with an arable crop. The trees, managed as hedgerows, are grown in wide rows and the crop is planted in the

interspace or 'alley' between the tree rows. During the cropping phase the trees are pruned and the prunings

used as green manure or mulch on the crop to improve the organic matter status of the soil and to provide nutrients, particularly nitrogen, to the crop. Alley

cropping retains the basic restorative attributes of the bush fallow system, allowing the farmer to crop the land

for an extended period. (Kang & Gutteridge)

Why practice alleycropping?Click

Windbreaks or shelterbreaks – reduce wind erosion (retain soil moisture, fuelwood, and provide a habitat

Differentiate between the following sustainable agriculture methods: terracing, contour plowing, strip cropping, alley cropping, and no-till.

Restoring Soil FertilityOrganic Fertilizers

Restoring Soil Fertility

Commercial Inorganic Fertilizer

Describe the positive and negative effects of inorganic fertilizers.

Click

Green Manure – plowing into soil plants currently growing

Composting

Restoring Soil FertilityDescribe the four environmental benefits of composting.Click

Restoring Soil Fertility

Crop Rotation – plant areas or strips with nutrient-depleting crops (tobacco, corn, and cotton deplete soil of nitrogen) one year and the

next year they plant the same areas with legumes

Which of the following factors did NOT contribute to the Dust Bowl in the United States?

A. No-till agricultureB. Removal of vegetative coverC. Soil erosionD. DesertificationE. Drought

If you were to practice crop rotation which of the following crops would be best for you rotate with corn?

A. TobaccoB. CottonC. MaizeD. SoybeansE. Sugarcane