SOILby: CHARMINE JANE DELA CRUZ

Soil

-defined as a top layer of the earth’s crust

-a mixture of mineral grains, organic materials, water, and gas.

- Provides support and nutrientsfor plant growth

Regolith Thin layer of loose, unconsolidated,

weathered material that overlies bedrock. Some earth scientists and engineers use

the terms regolith and soil interchangeably

Soil scientists include soil as only the upper layers of regolith.

Weathering

breaks down rocks to create soil. It can be caused by weather, water, or living things

COMPONENTS OF SOIL Minerals Organic matter Water Air

HUMUS

Humus is made of leaves, twigs, small animals, or other decayed substances.

Humus adds many nutrients to the soil.

Humus is in the topsoil.

CLAY Clay holds water well. It is sticky and can

be shaped when it is wet. But, it is very hard when dry. Clay is used for adobe or brick houses.

SILT Silt is very small, broken pieces of rock.

It is larger than clay, but smaller than sand. It is powdery when dry.

LOAM -most fertile soil mixture specially rich in sand and silt

with generous amounts of organic matter

SAND Sand is tiny grains of worn down rock. It

doesn’t hold water or have many nutrients.

Soil horizon

Soil Forming Factors Parent rock Climate Rates of plant growth and decay Slope aspect and steepness Time Transport of soil materials