1. Soil AG-BAS-17-(a – c), ELA10RC2 (a), SSWG8 (d), SES3
AG-BAS-17-(d, e), ELA10RC2 (a), SSWG8 (d), SES3
AG-BAS-17-a, ELA10RC2 (a), SSWG8 (d), SES3
AG-BAS-17-(f, g), ELA10RC2 (a), SSWG8 (d), SES3
AG-BAS-17-(h, i), ELA10RC2 (a), SSWG8 (d), SES3
AG-BAS-17-(j – l), ELA10RC2 (a), SSWG8 (d), SES3
AG-BAS-17-(m – o), ELA10RC2 (a), SSWG8 (d), SES3
AG-BAS-17-p, ELA10RC2 (a), SSWG8 (d), SES3

2. Soil
Soil is the upper layer of the earth’s crust capable of supporting plant life

3. What is soil made of?
Soil contains many things, both living and nonliving.
Soil should contain these basic ingredients:
Mineral Matter is composed of broken down rocks and minerals. It usually makes up the bulk of a soil’s mass. It also provides some nutrients for plants
Humus is decayed plant material. It adds organic nutrients to the soil and helps to alleviate compaction.
Air is essential to soil life. Plant roots cannot survive without oxygen.
Water is an important component of a good soil. It is essential for plants and many other soil organisms

4. Ideal Soil
The ideal soil contains 25% air, 25% water, 45% mineral matter, and 5% humus
What are some things that could cause the percentages to change?
Compaction: presses down the soil, in turn eliminating much of the pore spaces needed for air and water.
Drought: dry weather will cause a soil not to have the ideal amount of water
Flooding: too much water can push much needed oxygen out of the soil.
Farming methods such as no-till can add organic matter to the soil while conventional cropping methods sometimes deplete organic supplies.

5. Living things in the soil
Soil also contains many living organisms.
These organisms fall into two main categories:
Flora (plants)
Microflora: examples are fungi, algae, actinomycetes, etc.
Macroflora: examples are grass, ferns, etc. along with their roots
Fauna (animals)
Microfauna: examples are nematodes, bacteria, etc.
Macrofauna: examples are worms, mice, ants, etc.

7. Soil Particles
Sand is any soil particle that ranges from 2.0 to 0.05 mm in size.
Silt is any soil particle that ranges from 0.05 to mm in size.
Clay is any soil particle that is less than mm in diameter

8. Soil Texture
Soil texture is determined by the percentages of sand, silt, and clay in a soil.
Texture Affects
Compaction
Ease of tillage
Drainage
Capacity

9. Soil Formation Mass of material from which soil develops
May be moved about before soil is formed
Marine deposits
Wind-blown material
Weathering
Process of changing materials into soil
Gradual development of soil

10. What affects soil formation?
Climate influences how fast soil is formed and lost
Plants and animals
Plants make leaves, stems and roots, and other structures that decay to form organic matter
Dead animals also decay to help soil form
Slope and Drainage
Sloping land will have faster water runoff and dry out more quickly
Land in creek and river bottoms will stay wet longer and form a different kind of soil.
Hilly land often loses good soil to erosion
Level to gently rolling land is usually more fertile
Soils that hold water are slow to form and are low in fertility

11. Soil Profile A vertical section of soil at a particular place.
The profile shows layers of soil called horizons from the surface down to several feet

12. Soil Horizons
O-horizon: this horizon is at the very top of the profile. It is composed of organic material such as humus or decayed crops. Most cultivated land will not have an O-horizon because it has been turned under. The O-horizon is usually no more than 2" thick.
A-horizon: this horizon is usually called the topsoil. The topsoil is usually darker in color than the B-horizon because it contains more organic matter. Topsoil is usually gray to brown or black in color.

13. Soil Horizons
B-horizon: this horizon is commonly known as subsoil. It is below the topsoil and contains more clay and less organic matter. Colors of the B-horizon may be red, yellow, brown or varying combinations. The B-horizon sometimes affects percolation (water movement through the soil) because it can become hard and compacted.
C-horizon: the C-horizon is the parent material from which the soil is formed. It is between the B-horizon and the bedrock. It will eventually be broken down into soil.
R-horizon: the R-horizon is the bedrock that underlies the soil.

15. Water Table
The water table is the depth of the natural level of the water below the surface of the soil.
In areas that receive a lot of rainfall, the water table may only be a few feet deep. In deserts, it may be a few hundred feet deep.
The depth of the water table can be found by digging a hole in the ground.
The depth at which water will collect and stand in the hole is the water table.

16. Water table and Ag
The water table can sometimes affect how much submoisture is available to crops.
Submoisture is moisture that is available to crops from below the ground.
If the water table is low, submoisture may not be available and irrigation may be necessary

17. Forms of Water
Capillary Water-this is water that coats soil particles. The water is free to move from particle to particle by capillary action. Smaller particles have more surfaces and more capillary pull. Therefore, clay soils hold more capillary water than do sandy soils.
Hydroscopic Water-this is a thin layer of water that adheres to soil particles. It does not move about like capillary water does. Plants are able to use some of this water, depending on the amount in the soil.
Gravitational Water-this is water that fills in the pore spaces between soil particles. It may stand in some areas after rains. This is the type of water that causes flooded crop land.

18. Water Lost
Runoff: this is water that flows off the land before it has a chance to soak in. Terraces and other structures can help to slow runoff.
Evaporation: this is water that turns into water vapor and is lost into the atmosphere. During hot weather, large amounts of water can be lost through evaporation. Mulching crops can help prevent loss by evaporation

19. Water Lost
Transpiration: when plants release water into the air through the stomata in their leaves.
Percolation: this is the result of the downward pull of gravity on the water.
Harvested Crops: Many crops contain high levels of moisture. When the crops are harvested, the moisture is carried away with the crop. Tomatoes and watermelons are two examples of high moisture crops

20. Internal Drainage
Internal drainage is how fast water moves through the soil. Drainage can be classified in the following ways:
Excessively drained (course, sandy materials over 40" deep)
Well-drained (no gray mottles in top 30")
Moderately well-drained (no gray mottles in top 20")
Somewhat poorly-drained (no gray mottles in top 10")
Poorly-drained (gray/black mottles or matrix in top 10”)
Wet (surface water)

22. pH PH is a measure of the acidity of the soil pH range
The pH scale ranges from 0 to 14
0-6 is acidic
7 is neutral (distilled water)
8-14 is basic

23. pH and Ag It determines soil amendments needed.
It also determines nutrient availability (some nutrients become unavailable to plants at low or high pH levels)
Adjusting pH
If pH is lower than desired, add lime (1 ton of lime/acre will raise pH 1 point.)
If pH is higher than desired, add sulfur, iron sulfate, or aluminum sulfate

24. Land Capacity
There are seven things that determine a site’s capability class. They include:
Slope: the rise or fall of the land
Topsoil thickness
Amount of erosion
Topsoil texture
Permeability of the subsoil (how fast does water move into the subsoil?)
Drainage
Effective depth (the depth roots can effectively grow)

25. Land Classes Land Suited for Cultivation
Class I: Very Good Land. This class has few limitations. It is nearly level, has drainage, has deep soil, and is suitable for most crops.
Class II: Good Land. Not quite as good as Class I, but still useful. May have to use some conservation practices on this land.
Class III: Moderately Good Land. Has slopes up to 10% and slow drainage. Special conservation practices will have to be used on Class III land.
Class IV: Fairly Good Land. This land has more limitations than the first three but still may be used for cultivated crops if conservation practices are followed

26. Land Classes Land Unsuited for Cultivation
Class V: Unsuited for Cultivation. It may be wet, eroded and have steep slopes. Class V should be used for pasture.
Class VI: Not suited for Row Crops. This land is too steep to grow crops. It may easily erode. Class VI can be used for pasture.
Class VII: Highly Unsuited for Cultivation. Erosion and combinations of other problems place severe limitations on this land. It is best suited for forestry and wildlife.
Class VIII: Unsuited for Plant Production. This class has so many limitations it should only be used for wildlife and recreation. Stone Mountain and marshland are good examples of Class VIII land

27. Erosion Control – Vegetative
Conservation Tillage (no-till): method where the land is not plowed or cultivated thereby lessening the chances of erosion.
Mulching: this involves covering the soil with a layer of protective material such as crop stubble. Sometimes plastic is used. This also prevents loss of water.
Strip Cropping: this involves planting crops in strips, alternating the strips with crops that do not need cultivating.

28. Erosion Control – Vegetative
Crop rotation: some crops do not require as much cultivation and also add organic matter to the soil. By rotating with these crops we can improve the soil. Examples include:
Rye
Oats
Clover
Grated waterways: areas where water tends to runoff frequently can be planted in grass such as bahiagrass or bermudagrass to lessen the amount of erosion.

29. Erosion Control – Mechanical
Terracing: this involves building ridges or embankments that slow the rate of water runoff and divert it gently off the field.
Contour plowing - in contour plowing, cultivation is done across the slope rather than with it. This slows down the speed of water running off the land.
Diversion ditches and levees: these can sometimes divert water around a field to lessen erosion.

30. Drainage Problems
Drainage problems can sometimes be solved by digging drainage ditches or by laying drain tile to allow water to leave more quickly.