All About Soil All About Soil 4.7A
Soil can basically be separated into 5 main parts: Humus Clay Silt Sand Gravel
Humus: A dark, moist soil composed of bits of dead, rotting insects, animals, leaves, roots, sticks, and food. Humus adds nutrients to the soil which plants need to grow and live.
Clay: A soil that holds water. When wet, clay feels slippery and slimy Clay: A soil that holds water. When wet, clay feels slippery and slimy. It is made of particles that are smaller than 0.004 millimeters.
Silt: Soil that looks like fine grains or tiny pieces of rock Silt: Soil that looks like fine grains or tiny pieces of rock. Particles classified as silt measure from 0.004 millimeters to 0.006 millimeters.
Sand: Soil that is coarse and drains quickly Sand: Soil that is coarse and drains quickly. Sand particles measure from about 0.006 millimeters to 2.00 millimeters.
Gravel: Visible rock particles, sometimes referred to as pebbles.
Soil Profiles A soil profile is a view of a cross section of soil. Most living material exists in the top section, or topsoil. Plant roots often extend into the second layer, called the subsoil. The bottom two layers consist mostly of rock.
Characteristics of Soil Horizons 0 Horizon-located on surface, mostly O.M. (organic materials) A Horizon-Called Topsoil, good amounts of O.M. and minerals. B Horizon- Known as Subsoil, Less O.M. C Horizon- Mostly parent material, does little for plant growth.
Soil Texture Soil texture is the relative sizes of the different soil particles.
Major Soil Texture Classes Sand is the largest particle. Silt is a medium-sized particle. Clay is the smallest particle in size.
Characteristics of a Sandy Soil
Characteristics of a Silty Soil
Characteristics of a Clay Soil
Soil Structure Sand, silt and clay particles combine with one anther to form cluster called aggregates. The way in which aggregates or clusters are arranged is referred to as soil structure.
Soil Structure Categories
Modified from a presentation by Carrie Nagle, Mecklenberg Public Schools.