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فرمت فایل: word (قابل ویرایش و آماده پرینت)
تعداد صفحات 10
What is Soil? Soil is made up of several layers—we call the set of layers the “soil profile.” The major layers of the soil profile are (from top to bottom):
- Organic Layer: The top layer of soil is called the “Organic layer” or “topsoil.” This rich, dark layer has many nutrients to support plant growth.
- Subsoil: The next soil layer down from the topsoil is the subsoil. This layer of soil has a high mineral content, which comes from weathering of the bedrock underneath. The subsoil has some organic content, but doesn’t support plant growth very well because it lacks nitrogen and phosphorus nutrients.
- Mineral layer: The lowest level of the soil has almost no organic material in it, and is almost all mineral material. The mineral layer doesn’t support plant growth. It is derived from weathering of the underlying bedrock layer, and is mostly sand and rock.
- Bedrock: Deep down, under the soil layers is the bedrock. This rock is the “parent material” for the mineral part of soil—that means that all of the mineral components of soil come from the bedrock. As the bedrock layer gets weathered (broken down), the minerals move into the upper layers of the soil.
What is a Soil Component?
مقاله Layer soil
