2. What is Soil?
• Is the top layer of the Earth’s surface
suitable for the growth of plant life.
3. The Soil Profile
• Soil Horizon
• They are the layers of the different types
of soil found at different depths in the soil
profile.
• Soil Profile
• A vertical section through the soil
extending into the unweathered parent
materials and exposing all the horizons.
4. Master Horizons
• Are the A, B and C horizons.
• Typically found in most soils
• They are a part of a system for naming
soil horizons in which each layer is
identified by a code O, A, E, B, C & R.
5. The Horizons
• The O Horizon
• The organic layer
made of wholly or
partially decayed
plant material and
animal debris.
• Normally found in a
forest with fallen
leaves, branches and
other debris.
6. The Horizons
• The A Horizon
• Also called the
topsoil.
• The most fertile layer
of soil.
• Contains the most
organic matter.
• Usually the top or
first layer.
7. The Horizons
• The E Horizon
• Also called the layer
of eluviation.
• This is the zone of
the greatest leaching
of clay, chemicals
and organic matter.
8. The Horizons
• The B Horizon
• Also called the subsoil.
• Called the zone of
accumulation where
chemicals leached out of
the A horizon.
• Reason why most subsoil
has an increase
in clay content.
9. The Horizons
• The C Horizon
• Called the parent material.
• Lacks the properties of the A & B horizon.
• Less touched by soil forming processes.
10. The Horizons
• R Horizon
• Is the underlying bedrock such as….
• Limestone
• Sandstone
• Granite
14. Soil Texture - Sandy
• The largest of the soil
particles.
• Individual particles
can be seen with
the naked eye.
• Low moisture-holding
capacity.
15. Soil Texture - Loamy
• About equal parts of….
• Sand
• Silt
• Clay
• Ideal texture for most
non-container outside
plants.
16. Soil Texture - Clayey
• The smallest of the
soil particles.
• Clay particles stick
to one another.
• Has a high water-
holding capacity.
17. Textural Classes
• There are 12 textural classes.
• Represented on the Soil Texture
Triangle.
• Textural class determined by the
percentage of sand, silt, & clay.
18.
19. Soil Structure
• Refers to the way soil particles cling
together to form soil units or
aggregates, while leaving pore space
to….
• Store air.
• Store water.
• Store nutrients.
• Allow root
penetration.
20. Types of Soil Structures
• There are five types of soil structures.
• They are:
• Single grain
• Granular
• Platy
• Blocky
• Prismatic
22. Soil Structure - Granular
• Is the best for most
plants.
• Particles cling together to
form rounded
aggregates.
• It is commonly found in
A horizons.
• Peds are small usually
between 1 to 10
millimeters.
23. Soil Structure - Platy
• Usually found in E
horizons.
• Large, thin peds.
• Plate-like &
arranged in
overlapping
horizontal layers.
24. Soil Structure - Blocky
• Particles cling
together in angular
aggregates.
• Typical of soils with
high clay content.
• Typical of B
horizons.
• Peds are large about
5 to 50 millimeters.
25. Soil Structure - Massive
• Soil has no visible
structure.
• Hard to break apart
& appears in very
large clods.
26. Soil Structure
• More important to
producers who grow
plants in natural
soils because….
• Producers of
container grown
plants add
ingredients to make
growing media
desirable.
27. Soil Composition
• About 50% of the soil
should be solid
particles.
• 45% - Minerals
• 5% - Organic Matter
• About 50% of soil
should be pore space.
• 25% - Air/Pore Space
• 25% - Water
28. Soil pH
• pH has the most impact on the availability of
nutrients in the soil/media.
• pH Scale
• Ranges from 0 to 15.
• Indicates the level of acidity or alkalinity.
• 7 is considered neutral.
• Everything greater than 7 is considered alkaline
(basic).
• Everything less than 7 is considered acidic.
33. Land Capability Classes
• Assigning a number
to land.
• Eight classes used.
• I to VIII with I having
the best arability.
• Class I to IV can be
cultivated.
• V to VIII tend to have
high slope or are low &
wet.
34. Land Capability Classes
• Class I - Very good land.
• Very few limitations.
• Deep soil and nearly level.
• Can be cropped every year as long as land is
taken care of.
• Class II - Good land
• Has deep soil.
• May require moderate attention to conservation
practices.
35. Land Capability Classes
• Class III - moderately good land.
• Crops must be more carefully selected.
• Often gently sloping hills.
• Terraces and strip-cropping are more often used.
• Class IV - fairly good land.
• Lowest class cultivated.
• On hills with more slope than class III.
• Class V - Unsuited for cultivation.
• Can be used for pasture crops and cattle grazing, hay crops
or tree farming.
• Often used for wildlife or recreation areas.
36. Land Capability Classes
• Class VI - Not suited for row crops.
• Too much slope.
• Usually damaged by erosion with gullies.
• Can be used for trees, wildlife habitat, and
recreation.
• Class VII - Highly unsuited for cultivation.
• Has severe limitations.
• Best used for planting trees.
• Steeply sloping.
• Large rock surfaces and boulders may be found.
• Very little soil present.
37. Land Capability Classes
• Class VIII – Cannot be
use for commercial
plants.
• Cannot be used for row
crops or other crops.
• Often lowland covered
with water.
• Soil maybe wet or high in
clay.
• Best suited for wildlife &
recreation.
