Transcript Earth Matters: Investigating Soil

Earth Matters: Investigating Soil
Where Does My Lunch Come From?
How are these items connected to the soil?
Humans eat beef, eggs, and other
meat, which comes from animals
like cows and chickens.
The animals eat grains like corn,
grass and alfalfa, which all grow in
the soil. Humans also eat apples,
tomatoes, lettuce and other
vegetables which come from the
fruit, stem, leaves, and roots of
plants. The plants grow in soil.
Most of the land on Earth is
covered by soil.
Just like rocks, soils have different
physical properties such as:
color
Particle size
texture
odor
absorbency
Sand particles are the coarsest
particles found in soil.
Sand particles feel hard and
scratchy and don’t stick together or
hold water well.
Silt particles are smaller grains of sand
that feel smoother and softer.
Clay particles are the smallest of all.
Clay absorbs a lot of water and sticks
together.
Humus is a unique property of soil.
What is humus?
Humus contains the valuable nutrients
needed for plants to grow.
These valuable nutrients come from
decomposing plants and animals.
Millions of tiny living things such as
bacteria and fungi live in the soil and
help to turn dead plants and animals
into this dark, soft, sticky substance
known as humus.
Living animals contribute to properties
of the soil.
Earthworms, ants, and beetles make
spaces in the soil as they burrow
through it. These spaces are filled
with air and water which helps plants
to grow.
Most soils are a mixture of sand, silt,
or clay with varying amounts of
humus.
The percentage of sand, silt, and clay
are important for farmers and
gardeners because plants require
different conditions for the best
growth.
Too much sand can cause too much
water to drain away from plant roots.
A soil that is mostly clay may hold too
much water and cause the roots to rot.
Loam is a name given to a mixture of
sand, silt, and clay with a high
percentage of humus.
When a soil sample is mixed with
water and allowed to settle, the
particle layers will separate based on
particle size.
The larger particles will settle on the
bottom.
The smallest particles will be on top.
The properties of soil determine their
uses:
• Sand’s water-draining properties make it
perfect for playgrounds and sandboxes.
• Clay’s properties make it perfect for pottery or
moisture absorbing kitty litter.
Loam, rich topsoil, or potting soil
provides the nutrients for plant
growth. Soil is the beginning of the
food chain.
Soil’s capacity to sustain life, both
plant and animal, makes it one of our
most valuable resources.
Let’s look at some different soils:
• loam (potting soil)
• sand
• clay
Procedure:
1. Using your soil samples, measure
equal amounts of each soil and place in
the container.
2. Add water until the container is ¾
full. Place the lid on the container.
3. Make sure the lid is secure.
4. Shake well and allow time for the
soil to settle.