第9章 Lesson 9: About Soils

Soil is found on the top layer of the Earth. It is made of a mixture of rock, minerals, plants, and some living or dead animals (mostly insects). This nutrient-rich layer of soil extends a few feet downwards. This is about how far the roots of plants grow.

Soil is made up of all the nutrients that plants need to live. Some areas of the world like desert regions have very poor soil. Here it is very difficult for plants to grow. Tropical rainforests also have poor soil. The rainforests get enough rain to grow plants, but the poor soil is caused by so much living vegetation.

For over a million years, the soil of the Earth has been developing. Weather has played an important role in shaping soil. The top rocky layer of the Earth has been ground down into smaller and finer grains. Plants and animals have helped to deposit nutrients.

An important part of the soil is the living part. Bacteria (any microscopic plant that lives in soil, water, or organic matter), algae (any plant that forms the lowest division of the plant kingdom and includes mostly brown or red plants growing in water) and fungi (any flowerless plants like mushrooms) are living parts of the soil. They help more complex life forms live.

The soil under our feet has a darker colour than the dirt. This is caused by plants and animals (living and dead) that are found within it.

Soil is formed by geology, climate, topography, biology, and the passing of time.

—Geology is the land.

—Climate is temperature and weather conditions.

—Topography is the type of landform.

—Biology deals with living organisms and their life processes.

The next time you sit on the grass to have a picnic, get your shoes dirty, or walk barefoot, maybe you will be reminded of the importance of soil.

I. Word List

microscopic: too small to see

nutrients: important types of food that plants and animals need

vegetation: plants

finer: softer

deposit: to put into

II. Choose the correct answer for each sentence.

1. Most of the animals in soil are ________.

a. birds b. insects c. mammals d. rodents.

2. Desert areas have very _________ colourful soil.

a. good b. thin c. poor d. thick

3. Bacteria is ________.

a. microscopic b. very large c. an insect d. delicious.

4. Climate is similar to ________.

a. geology b. biology c. soil d. weather

5. An example of fungi is __________.

a. mushroom b. cheese c. bacteria d. rocks.

III. Circle the sentences that are true.

1. We can see bacteria.

2. Animals are in the soil.

3. Soil has been forming for a long time.

4. Soil is very important for plants.

5. Rainforests have very good soil.

IV. What's the word? Choose the correct words from the story.

1. a small kind of plant: a _ _ _ _

2. a flowerless plant: f _ _ _ _

3. a very dry area: d _ _ _ _ _

4. the bottom part of plants: r _ _ _ _

5. the land: g _ _ _ _ _ _

6. not simple: c _ _ _ _ _ _