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Reading Science
Soil
By Cindy Grigg
The soil where you live might be very different from soil in other places. You might have noticed that soil can be different colors. Soil can have pieces of different sizes. Soil can feel very soft or very hard.
2 Soil is made of pieces of rock. If you look closely at a rock, you will see many tiny holes and cracks. When it rains or snows, water fills these holes and cracks. The water freezes and pushes against the rock. The rock slowly breaks apart. Over many years, the water causes rock to break into small pieces and form soil.
3 Soil also has air, water, and matter that was once alive. When plants and animals die, they decay. The decayed matter is called humus. It becomes part of the soil. This adds nutrients to the soil.
Nutrients are materials plants need to live and grow. Humus gives
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Name_________________________________________Class____________________Date___________ soil a dark color.
4 When a rock breaks apart, its minerals become part of the soil.
Some minerals can give the soil a certain color. The mineral iron can give soil a red color.
5 Clay soil is tightly packed soil with tiny grains. Clay soil feels very smooth. Clay soil has many nutrients and holds water well. Many plants cannot grow in clay soil. The grains are so close together the plant roots cannot spread easily through it.
6 Sandy soil is loose and easy to dig. It has large grains in it. Most plants do not grow well in sandy soil. Sand does not hold water so plants dry out quickly. Sandy soil has few nutrients that plants need.
7 Loam is a mixture of clay, sand, and humus. Many plants grow well in this soil. Loam holds water and has many nutrients for plants.
8 The soil you usually see is called topsoil. Topsoil is the upper surface of the earth's crust. It is usually no deeper than eight inches from the surface. Plants need healthy topsoil to survive. It may take hundreds of years for one inch of topsoil to form.
9 People can grow plants in ways that use soil wisely. Some plants, such as peas, add nutrients to the soil. Adding dead leaves to soil
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Name_________________________________________Class____________________Date___________ adds nutrients, too. Farmers can rotate their crops. This means not planting the same crop in the same soil year after year.
10 People can plant trees to help stop soil erosion. Erosion is the movement of soil or rocks by wind or water. Every year, wind and water move tons of soil and rocks. Tree roots help hold soil in place to stop soil erosion. Trees also help to stop the wind from blowing away loose soil. Other plants help stop erosion, too. Plants help keep soil from being eroded by protecting the soil from wind and water.
The plants' roots help to hold down the soil. People can stop cutting trees to help stop erosion. They can plant more plants.
11 Soil is important to people. People eat plants that grow in soil.
Some materials in clothing, like cotton, also come from plants. Paper comes from trees that grew in soil. Soil is a natural resource that comes from the earth. The earth has a limited amount of natural resources. People must be careful not to waste them.
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Name_________________________________________Class____________________Date___________
1.
Soil is made of:
Pieces of rock
Air and water
Matter that was once alive
All of the above
2.
What is humus?
Decayed matter that was once alive
Minerals
Air and water
All of the above
3.
What does humus do for soil?
Adds water
Adds nutrients to the soil and gives it a dark color
Adds minerals
4.
How do minerals become part of the soil?
Minerals must be added to the soil by man.
Minerals come from rocks.
Minerals come from decayed matter that was once alive
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5.
Which type of soil is tightly packed with tiny grains?
Loam
Clay
Humus
Sand
6.
Which type of soil is the best for growing plants?
Sand
Clay
Loam
7.
What is erosion?
Movement of soil or rocks by wind or water
Matter that was once alive
A type of soil
8.
What is crop rotation?
Planting trees to stop erosion
Not planting the same crop in the same soil year after year
Movement of soil or rocks by wind or water
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