From Bedrock to Soil
• What is soil formed
from?
• What is bedrock
• What is humus?
• What are soil
horizons?
The Source of Soil
• Soil is a loose mixture of small mineral
fragments, organic matter, water, and air that
can support the growth of vegetation.
• Bedrock is the layer of rock beneath soil.
• Parent rock is the rock formation that is the
source of soil.
• Soil that is blown or washed away from its
parent soil is called transported soil.
• Wind, water, and movements of glaciers can
transport or move soil from one place to
another.
Soil Properties
• Soil is made from different-sized materials.
• Soil texture is the soil quality based on the
proportions of soil particles.
• Soil texture can influence the ability of
water movement through the soil.
• Soil structure is the arrangement of soil
particles.
• Consistency describes a soil’s ability to be
worked and broken up for farming.
• Infiltration is the ability of water to move
through soil.
Soil Properties
• Some soils are rich in nutrients, some are
poor in nutrients.
• Soil fertility is the soil’s ability to hold
nutrients and to supply nutrients to a plant.
• Humus is the dark, organic material
formed in soil from the decayed remains of
plants and animals.
Soil Horizons
• Soil horizons are the
horizontal layers of soil.
• The top layer of soil is
called topsoil, containing
more humus than the
other layers of soil, rich
in nutrients plants need
to be healthy.
• Good topsoil is
necessary for farming.
Soil pH
• Soils can be acidic or basic.
• The pH scale, ranging from 0 to 14, is
used to measure the acidity of a
substance.
• 7 is neutral; below 7 is acidic; above 7 is
basic.
• Different plants need different types of soil.
• The right pH for a soil depends on the
plants growing in it.
Summary
• Soil (loam) is formed from the weathering of
bedrock.
• Soil texture affects how soil can be worked
for farming and how well water passes
through it.
• The ability of soil to provide nutrients so that
plants can survive and grow is called soil
fertility.
• The pH of a soil influences which nutrients
plants can take up from the soil.
• Different climates have different types of soil,
depending on the temperature and rainfall.
Quick Check
1.Soil that is blown or
washed away from its
parent rock
2. The layer of rock beneath
the soil
3. A rock formation that is
the source of mineral
fragments in the soil
4. A loose mixture of
mineral fragments,
organic material, water,
and air that can support
vegetation
a. soil
b. transported soil
c. parent rock
d. bedrock
Quick Check
1. Soil quality based on
the proportions of
soil particles
2. The arrangement of
soil particles
3. Ability of water to
move through soil
4. Soil’s ability to be
broken up for
farming
a. soil structure
b. infiltration
c. consistency
d. soil texture
Quick Check
What is soil’s ability to hold nutrients and to
supply nutrients to a plant?
a.
b.
c.
d.
Soil structure
Soil texture
Soil horizons
Soil fertility
Quick Check
What do we call the removal of substances
from soil due to water passing through it?
a.
b.
c.
d.
Wedging
Infiltration
Erosion
leaching
Quick Check
What is the layer of soil that often contains
the most humus?
a.
b.
c.
d.
Horizon
Parent rock
Topsoil
bedrock
Quick Check
What is soil that has a pH below 7 called?
a.
b.
c.
d.
Neutral
Acidic
Basic
midpoint
Quick Check
What is the correct pH for growing plants?
a.
b.
c.
d.
7
Above 7
Below 7
It depends upon the plant
Soil Conservation
• Why is soil important?
• How can human
activity affect soil
erosion?
• What are three
important benefits
that soil provides?
• List five methods of
soil conservation.
Soil Conservation
• Soil can be endangered, just like plants
and animals.
• Soil is important because it provides
nutrients to plants, provides houses for
animals, and stores water.
• It takes thousands of years for soil to form,
it is not easy to replace.
• Soil conservation is a method to maintain
the fertility of the soil by protecting the soil
from erosion and nutrient loss.
The Importance of Soil
• Soil provides minerals and other nutrients
for plant life.
• All animals get their energy from plants.
• Soil also provides a place for animals to
live.
• The region a plant or animal lives is called
a habitat.
• Soil holds water for plants to get the
moisture or nutrients they need.
Soil Loss and Damage
• Soil loss is a serious problem around the
world.
• Soil damage leads to soil loss.
• Soil becomes damaged from overuse, by
poor farming techniques.
• Soil damage also can come from
overgrazing.
• Overused soil can lose its nutrients and
become infertile
Soil Loss and Damage
• Plants will not grow in soil that is infertile.
• Without plants to hold and help the cycle
water, the area can become a desert.
• Without plants and moisture, soil can be
blown or washed away.
• Soil left unprotected can be exposed to
erosion.
• Roots from plants and trees act like an
anchor to hold soil in place.
Soil Erosion
• Human activity can accelerate soil erosion
when those activities affect plant roots.
• Plants and trees protect the soil.
• By taking care of the vegetation, you also
take care of the soil.
Summary
• Soil is important for plants to grow, for
animals to live in, and for water to be
stored.
• Soil erosion and soil damage can be
prevented by no-till farming, contour
plowing, terracing, using cover crop, and
practicing crop rotation.