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# Soils Review The document describes the components of soil. ## Soil Main Parts * **Minerals:** These come from parent materials like rocks, deposited by glaciers, wind or rivers. Minerals are part of soil when rocks break down through weathering. * **Organic Matter:** This refers to the...

# Soils Review The document describes the components of soil. ## Soil Main Parts * **Minerals:** These come from parent materials like rocks, deposited by glaciers, wind or rivers. Minerals are part of soil when rocks break down through weathering. * **Organic Matter:** This refers to the remains of plants and animals. When they decompose, bacteria in the soil break them down which releases nutrients creating humus, giving the soil its dark color. * **Moisture:** Water plays a key role dissolving the nutrients and being taken up by the plant roots. Water also contributes to the chemical and physical processes of breaking down rock and organic matter. * **Air:** Plants need air around their roots since they require oxygen for respiration. Loose materials and other creating pockets of air. Worms, insects, and small animals also contribute to air pockets in the soil. ## Soil Layers * **Humus-1:** This layer is rich in organic matter and minerals. * **Topsoil-2:** This layer contains a high concentration of humus, minerals, and good structure for growing plants. * **Subsoil-3:** This layer contains fewer organic matter and more minerals. * **Parent material-4:** This is the underlying layer of weathered rock.