Reilly - Explore Soil!: With 25 Great Projects

Newest titles in the Explore Your World! Series Check out more titles at www.nomadpress.net Nomad Press A division of Nomad Communications 10 9 8 7 6 5 4 3 2 1 Copyright 2015 by Nomad Press. All rights reserved. No part of this book may be reproduced in any form without permission in writing from the publisher, except by a reviewer who may quote brief passages in a review or for limited educational use. The trademark Nomad Press and the Nomad Press logo are trademarks of Nomad Communications, Inc. Illustrations by Bryan Stone Educational Consultant, Marla Conn Questions regarding the ordering of this book should be addressed to Nomad Press 2456 Christian St. White River Junction, VT 05001 www.nomadpress.net CONTENTSIntroduction
What Is Soil? Chapter 1
Home Sweet Soil Chapter 2
How Soil Works Chapter 3
Soil and People Chapter 4
Soil and Disease Chapter 5
Soil and Farm Animals Chapter 6
Soil and Plants Chapter 7
Dangers to Soil Chapter 8
What Can We Do? Interested in primary sources? Look for this icon. Use a smartphone or tablet app to scan the QR code and explore more! You can find a list of URLs on the Resources page. When youre playing in your back yard or walking down the sidewalk, what do you see when you look down at the ground? Grass, cement, leaves, trash? Most of the time, youll also see something many people call dirt. You might think, Whats the big deal about dirt? Its everywhere. When youre playing in your back yard or walking down the sidewalk, what do you see when you look down at the ground? Grass, cement, leaves, trash? Most of the time, youll also see something many people call dirt. You might think, Whats the big deal about dirt? Its everywhere.

That dirt is actually soil , which is very important to life on Earth. Its one of the three most important natural resources on our planet, along with air and water. Without soil, there wouldnt be life on Earth. WORDS to KNOW soil: the top layer of the earth, in which plants grow. natural resource: something from nature that people can use in some way, such as water, stone, and wood. In the same way that you have skin covering your whole body our planet has soil covering its entire surface.

Soil covers the ground in natural places, such as meadows, gardens, forests, and your back yard. Some places have only a thin layer of soil. In other spots, it can be several feet thick. Soil does a lot of work for us. It is a habitat for tiny organisms. Most of our plants need it to grow.

And soil recycles nutrients and filters our water, too. Theres a lot going on under your feet! WHATS IN SOIL? Soil is made up of lots of different materials. The organic matter in soil includes little bits of dead plants and animals. There are tiny bits of inorganic matter, too, such as broken-down rocks and pebbles. There are also even smaller particles in soil, such as sand, silt, and clay. organism: a living thing. nutrients: substances in food, soil, and air that living things need to live and grow. substance: the material that something is made of. organic matter: rotting plants and animals that give soil its nutrients. organic: something that is or was living. inorganic: not living. particle: a tiny piece of matter. silt: particles of fine soil, rich in nutrients. Sand is the largest particle youll find in soil. Sand is the largest particle youll find in soil.

Have you ever scooped up a handful of soil at the beach and looked at it closely? Youll be able to see each little grain of sand. Silt particles are smaller than sand. If you drag your hand lightly along the bottom of a running stream, you can snag a little bit of soil thats being carried along with the current. If you look at it very closely you might be able to see individual particlesbut theyre really small! Clay is made of the smallest particles. You wont be able to see the individual particles just by looking at a lump of clay. You need a microscope to see them because theyre so small.

When clay particles get wet, they turn really sticky and clump together. Have you ever played with clay? Squeezed between all these soil particles are air and water. Thats how plants grow in soilthey push their roots between the particles to get the water and nutrients they need. THE FIRST STEP Rocks are very hard. If you drop one on your foot, it hurts! But they can be broken into smaller pieces under the right conditions. Thats how soil starts.

Rock is called the parent material of soil because its where most soil comes from. Soil comes from the parent material of rock just as you come from your parent! Water, ice, and wind break down bedrock through time. Water can move forcefully enough to push rocks, tumble them around, and knock them into each other. As the water continues to roll them, little pieces break off, and then they start tumbling around, too. In time, the pieces get smaller and smaller. SLIP-SLIDING AWAY There are some locations where soil cant form.

Have you ever seen craggy mountain peaks? They are often bare, just peaks of exposed rocks. Thats because gravity pulls any soil-making materials, such as sand particles and organic matter, down the sides before any layer of soil has a chance to form. Water and wind wash materials down from mountaintops, too. WORDS to KNOW parent material: material that eventually becomes soil, such as rock. bedrock: the layer of solid rock under soil. gravity: the force that pulls things down toward the surface of the earth.

Ice can break down rocks, too. Rainwater seeps into cracks in the bedrock. When the water freezes, it expands . This forces the cracks to get wider and wider, sometimes splitting the entire rock into smaller pieces.