What Is Soil?

from Let's Do Science 3 – Text Book B

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Soil is a mixture of weathered rock, minerals and other living and non-living things. In between the small pieces that make up soil are spaces that contain air and water. An important part of soil is humus. Humus contains the remains of dead plants and animals and is often darker in color than other parts of soil. Humus adds nutrients to the soil which are essential to plants and other living things. Activity 8.5AB Think Deeply When gardening, people often add extra ‘topsoil’ to gardens. How does this help plants grow? ation n k Deeply ardening, add extra ‘top to gardens. How help plants grow catio

Many plants need soil to survive. Plant antl to survivve. Planve roots grow down into the soil and take takeo the soil aand taa in the nutrients, minerals and water the ater theinerals and wat plants need to live and grow. As plants As plantsve and gro As are the main source of food for people or peopleurce of food and other animals, soil is important to all ortant to allnimals, soil is im life on Earth. h. any animals, suc other burrowing

Many animals, such as ants, worms and worms and other burrowing animals also live in soil. live in soil.

Did You Know?

Compost is a soil very high in nutrients. It is made from the decomposition of organic matter – usually plant parts. You can make compost by putting food scraps in a compost bin in your garden. A compost bin is like an upside-down trash can.

p compost How Soil Forms Soil forms when wind, water and changes in temperature break down rocks into small pieces. This process is called weathering. The pieces of weathered rock are carried by wind and water to new places. The remains of dead plants and animals also form part of the developing soil. As more weathered rock particles are added over time, soil begins to form in layers. The soil layer closest to the surface of the Earth is called topsoil. This part of the soil contains lots of humus and is rich in nutrients. Topsoil also has large spaces for air and water. Most plants and soil-living animals get the things they need from the topsoil.to soilheth ducation hanges in ges in to small pieces mall pieces ng. ck are carried b ck are carried aces. The remain ces. The remai s also form part also form par d rock particles ck particles gins to form in la s to form in closest to the sust to the s psoil. This part o This part o s and is rich in nu d is rich in n paces for air and aces for air an ving animals get animals get il topsoil. oil.

Regal

Below the topsoil is subsoil. Subsoil contains less nutrients and smaller spaces for air and water. Below the subsoil is a layer of weathered rock fragments that sit on a layer of bedrock. Soil forms in layers. topsoil (organic layer) subsoil ation psoil (o psoil (top