Properties of Soil

Where does soil come from and how does it form? Most soils were originally created through the breaking down (weathering) of the solid rock which, at one time, formed the earth. Soil also comes from dead leaves, broken trees, dead bugs and those kinds of things. This decayed plant and animal material is called humus.

Why is soil so important? Soil is the foundation for life on Earth. We depend on plants for food and land plants need soil to grow! Soil is important for plants because it holds roots, stores nutrients, and provides support for plants. You would have a hard time living without soil because soil contains the minerals all living things need!

Does soil come in different colors? Soil can come in black, red, yellow, white, brown, and gray. Color development and distribution of color within a soil profile are part of weathering. Color is also affected by the environment. With depth below the soil surface, colors usually become lighter, yellower, or redder.

What kind of textures does soil have? The way a soil "feels" is called the soil texture. Soil texture depends on the amount of each size of particle in the soil. Sand, silt, and clay are names that describe the size of individual particles in the soil. Sand are the largest particles and they feel "gritty." Silt are medium sized, and they feel soft, silky or "floury." Clay are the smallest sized particles, and they feel "sticky" and they are hard to squeeze.

What kind of textures does soil have? soil separate fraction namesize range very coarse sand2.0 to 1.0 mm; coarse sand1.0 to 0.5 mm; medium sand0.5 to 0.25 mm; fine sand0.25 to 0.10 mm; very fine sand0.10 to 0.05 mm; silt0.05 to mm; clay<0.002 mm.

Relative Particle Size Comparison Sand Silt Clay If you made a particle of each type larger, this is how they might compare.

Sand The largest particles in soil, besides rocks Can be seen with the naked eye lacking nutrients to grow plants Drains water very quickly Does not “hold” much water Feels “GRITTY”

Silt Between sand and clay in particle size Provides some nutrients for growing plants Erodes easily Drains water slowly Forms a surface crust after rainfall Feels like “FLOUR”

Clay Smallest of the soil particles Microscopic in size Very high in nutrients Holds more moisture than sand or silt Feels smooth when wet Does not drain well Becomes cloddy if not managed Feels “STICKY”

Potting Soil Made up of a well-balanced mix of sand, silt, clay, and humus Best type of soil for growing plants Provides most nutrients for growing plants Holds moisture Drains well so air can reach the roots

Does soil retain water? The space between soil particles is referred to as "voids" or "pores". This is the area where water can reside in the soil. Therefore, the composition of a soil has a significant effect on the amount of water it can hold or retain. Image courtesy of Profile Products, 2002, PROFILE Improves Any Soil Structure For Superior Performing Designs, 20 Jan Permeability: Click the link below to see how long it might take water to travel 1 meter in different soil types....

Soil is a mixture of weathered rock, humus (decayed parts of once-living things), air, and water. Soil is important to all living things. It contains minerals and other things that plant and animals need for growth. Soil takes a long time to form, so we must take care of it!!!