3rd grade science SOL – soil
what is soil?
an important natural resource that is made up of different substances found in the earth
why is soil important?
because many plants grow in soil and it provides support and nutrients for the plants
what is weathering?
when rocks and other materials in the Earth’s surface are broken down into smaller pieces by weather, water and living things
what is erosion?
a force that gradually wears away soil and its nutrients. It can be found in areas with steep slopes or where little rain falls. It can also be found in areas where trees have been cut down and in overpopulated rural areas.
what are nutrients?
materials that plants and animals need to live and grow
what are the 3 layers of soil?
topsoil, subsoil, and bedrock
what is topsoil?
the top surface of the soil where plants grow and animals live. It is a mixture of weather rock fragments and humus.
what is subsoil?
the layer underneath the topsoil. It is made up mostly of clay. It is not very good for growing plants.
what is bedrock?
the layer underneath subsoil. It is made up of partly weather rock and solid rock.
what are the substances of soil?
humus, clay, sand and silt
what is humus?
humus is decayed plant and animal matter that is found in the soil. It adds nutrients to the soil so plants can grow.
what is clay?
a red or yellow type of soil that holds water well and contains nutrients
what is sand?
a type of soil made up of small grains of weather rock. It does not hold water well and has few nutrients
what is silt?
a type of soil made up of very small broken pieces of rock. The pieces are smaller than the rock pieces in sand, but larger than the rock pieces found in clay
what is a natural resource?
something that we use that can be found in nature
what is the most important role of soil?
hold the water and nutrients necessary for plants to live and grow
why should soil be conserved?
because it is important to life on Earth and it takes hundreds of years to form
how can we conserve soil?
protect plant life. Plant life helps to protect Earth’s topsoil from erosion
what is erosion?
a force that gradually wears away the soil and its nutrients
how can plants help stop erosion?
plants help hold the soil in place with their roots. Their leaves protect the soil from drying sun, the driving winds, and the pouring rain.
what are the life needs of people and animals?
air, food, water, shelter
how do plants provide us air?
they give off a gas called oxygen that humans and other living things need to stay alive.
how do plants provide us with food?
insects and plant-eating animals eat leaves, roots, nuts, berries, flowers, and fruits. People also get food from plants. A few examples from Virginia are corn, apples, soybeans, tomatoes and peanuts.
how do plants provide shelter?
Animals and other living things depends on plants for shelter. Examples: beavers use timber to make dams, birds use twigs and grass to make nests, humans use lumber to build.