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Soil
1. Project
Subject : English
Topics : Soils
Agricultural University Of Tirana
Forest engineer/ First Group
Work by : Inesa Mata
Accepted :
2. We know more about the movement of
celestial bodies than about the soil underfoot.
- Leonardo da Vinci
3. Soil: Definition
• Solid earth material that has been
altered by physical, chemical and organic
processes so that it can support rooted
plant life.
• Engineering definition: Anything that
can be removed without blasting
4. Why are soils important?
Great integrator
Producer and
absorber of
gases
Medium for
plant growth
Medium of crop
production
Home to organisms
(plants, animals and
others)
Waste decomposer
Snapshot of
geologic, climatic,
biological, and
human history
Source material for
construction,
medicine, art, etc.
Filter of water
and wastes
Essential natural resource
7. Soil ColorSoil Color
Color is the most obvious characteristic of soil.
Soil color is influenced by the oxidation state of iron
and manganese.
What are some colors encouraged by well aerated
conditions?
REDRED YELLOWYELLOWBROWNBROWN
What are some colors encouraged by poorly aerated
conditions?
GRAYGRAY BLUEBLUE
8. Red Soil
• Red soil is a group of soil that develop in a warm, temperate,
moist climate under deciduous or mixed forests and that have
thin organic and organic-mineral layers overlying a yellowish-
brown leached layer resting on an illuvial (see illuviation) red
layer. Red soils generally derived from crystaline rock. They are
usually poor growing soils, low in nutrients and humus and
difficult to cultivate because of its low water holding capacity.
Red soils denote the second largest soil group of India covering
an area of about 6.1 lakhs sq. km (18.6% of India's area) over
the Peninsula from Tamil Nadu in the south to Bundelkhand in
the north and Rajmahal hills in the east to Kachchh in the west.
They surround the black soils on their south, east and north.
9. Brown Soil
• Brown earth is a type of soil. Brown earths are mostly located
between 35° and 55° north of the Equator. The largest expanses cover
western and central Europe, large areas of western and trans-Uralian
Russia, the east coast of America and eastern Asia. Here, areas of
brown earth soil types are found particularly in Japan, Korea, China,
eastern Australia and New Zealand. Brown earths cover 45% of the
land in England and Wales. They are common in lowland areas (below
1,000 feet) on permeable parent material. The most common
vegetation types are deciduous woodland and grassland. Due to the
reasonable natural fertility of brown earths, large tracts of deciduous
woodland have been cut down and the land is now used for farming.
They are normally located in regions with a humid temperate
climate. Rainfall totals are moderate, usually below 76 cm per year,
and temperatures range from 4°C in the winter to 18°C in the summer.
They are well-drained fertile soils with a pH of between 5.0 and 6.5.
10. Factors of Soil Formation
• Climate
• Organisms
• Parental Material
• Topography
• Time
11. Factors of Soil Formation
Climate
• Temperature and precipitation
• Indirect controls (e.g., types of plants)
• Weathering rates
The greater the rainfall amount, the more rapid
the rate of both weathering and erosion.
12. Factors of Soil Formation
Organisms
• Types of native vegetation
• Weathering is dependent of plant growth
• Plant and animal activity produces humic acids
that are powerful weathering agents.
• Plants can physically as well as chemically
break down rocks.
• Plants stabilize soil profiles, Animals
(including humans) tend to increase erosion.
14. Factors of Soil Formation
Topography:
• Ground slope
• Elevation
• Aspect (e.g., north facing vs. south
facing slopes)
15. Factors of Soil Formation
Time
• Development and destruction of soil
profiles
• Typical reaction rates are slow, the
longer a rock unit has been exposed,
the more likely it is to be weathered.
16. Soil TextureSoil Texture
The look and feel of a soil is referred to as SOIL TEXTURE and is
determined by the size and type of particles that make up the soil
(including the organic but mostly referring to the inorganic material).
The size of the ex-rock pieces (now the inorganic soil particles) varies
substantially, from large bits of gravel to much, much smaller clay pieces.
How you refer to the soil particles is actually based on their size:
•Gravel - particles greater than 2 mm in
diameter
•Coarse sand - particles less than 2
mm and greater than 0.2 mm in diameter
•Fine sand - particles between 0.2 mm
and 0.02 mm in diameter
•Silt - particles between 0.02 mm and
0.002 mm in diameter
•Clay - particles less than 0.002 mm in
diameter
17. SandySoils
Sand particles are LARGE = small surface area. Therefore:
•Sand drains easily = POOR ABILITY TO RETAIN MOISTURE
•Little chemical activity = LITTLE NUTRIENT BONDING
SiltSoils
Silt particles = limited surface area
•Little chemical activity = LITTLE NUTRIENT BONDING
•May compact under heavy traffic = poor air and water movement
ClaySoils
Clay particles are SMALL = large surface area. Therefore:
•Water adheres very well to clay = HIGH ABILITY TO RETAIN MOISTURE
(however, this water can be hard even impossible for the plant to
use).
•Very chemically active = GOOD NUTRIENT BONDING
18. Soil StructureSoil Structure
•Soil structure is the combination or arrangement
of primary soil particles into secondary units
•The way soil particles are arranged to form
stable aggregates
•Compare this to clods, which are caused by
disturbance (plowing or digging)
•Compaction – results from implement traffic,
stable soil aggregates are broken down
19. Common Types of SoilCommon Types of Soil
StructureStructure
Granular
Platy
Prismatic
Columnar
Blocky
Single Grain
Massive
Plow layer
Are individual particles of sand silt &
clay grouped together in small grains.
Is made up of soil particles aggregated in
thin plates or sheets piled horizontally
Are soil particles which have
formed into vertical columns
Are soil that cling
together in nearly square
20. National Archives: 114 SC 5089
A nation that destroys its soils, destroys itself.
– President Franklin D. Roosevelt, Feb. 26, 1937.
