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Loess field in Germany (loess is wind-blown dust)
Soil horizons are caused by combined biological, chemical and physical effects

Soil (sometimes called dirt) is the combination of rock, mineral fragments (pieces), organic matter (dead and living things), water and air.

It is mostly made up of grains of rock (weathered by wind, rain, sun, snow) and humus. The type of soil depends on the mix of humus and on the size of the grains of the rock. The grains can be very small and smooth, such as clay, or they can be larger, like grains of sand or even a piece of gravel.[1]

Soil is important to our ecosystem for six main reasons: first, soil is a place for plants to grow; second, soil controls the purity of water that moves through it; third, soil recycles nutrients from dead animals and plants; fourth, soil changes the air that surrounds the Earth, called the atmosphere; fifth, soil is a place to live for animals, insects and very small living things called micro-organisms; sixth, soil is the oldest and the most used building materials.[2] The climate is very important when soil is made. Soil from different climates have very different qualities.

Related pages[change | change source]

References[change | change source]

  1. Learn Science, intermediate, grades 5 to 6 by Mike Evans and Linda Ellis
  2. Brady and Weil 2008. The nature and properties of soils. 14th ed.