Soil

Soil, also known as Dirt, is a common material that usually makes up the upper layer of the ground. Soil is apt to have plants growing in it, and plant matter, from recently living plants, embedded in it.

Multiple factors can affect a soil's fertility. Moisture drains out of sandy soil. Soil with logs of clay can get waterlogged. Soils containing recent volcanic ash can be rich in minerals plants need. Some plants, like legumes fix Nitrogen, another important nutrient plants need, into the soil.

Bad farming practices can strip soil of nutrients, leading to poor harvests.

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  Soil cross-section, Leithenwater Forest, UK
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  Cross section of soil and sub soil