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A Soil Profile

What is a soil profile?

If you took a chunk of soil from the ground, say about a foot or two deep, you will see a change in the colors and texture as you go deeper into the ground. You might be able to see some of the same things shown in the soil profile below.


How is soil formed?

Soil is formed in several ways. The break down, or weathering of rocks, is one way soil is formed. Water, wind, and ice also help to create soil. Earth materials are carried by water, wind, and ice and are eventually dropped in places where they settle and mix with other materials to become soil. But the key ingredient to the making of soil is the living and once-living things that are found in it. These living and dead organisms are called organic matter. They turn the sand, silt, and rock pieces into a mixture that is good for more life to live and grow.

What is in soil?

Soil is a mixture of four main ingredients: weathered rock, organic matter, air, and water. The weathered rock can be in the form of sand, silt, clay, pebbles, or other size rocks. Organic matter can be anything from old leaves, dead animals and plants, or tiny living things. The last two ingredients in soil are from the nonliving world. These two ingredients are air and water. Without air and water, the tiny organisms found in soil cannot live, grow, and help dead matter to decay.

What are the layers of soil?

First you find topsoil. This is the ground layer we walk upon, commonly referred to as 'dirt'. It is nutrient rich due to the decaying plant and animal matter, called 'humus', within. Beneath the topsoil we find the lighter colored subsoil. Subsoil is the middle layer that contains large rocks alongside minerals washed out of the topsoil. Within the subsoil area there is a layer called substratum, this is the deepest layer where rocks weather to form new subsoil. Beneath the substratum is the solid, hard bedrock, untouched by weather, plant or animal.

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