All about Soil
(and Soil Types)

Soil is composed of varying amounts of sand, silt, and clay.   

Sand is mainly rock fragments and hard minerals. It contains few plant nutrients.  Sand is the largest of the three types of soil particles.  Sand in the soil (in moderate amounts) improve drainage and aeration.
Silt is ground up sand (quartz) and rock minerals. Silt is between sand and clay in terms of size. Silt contains few nutrients by itself, but it can have nutrients clinging to its surface.
Clay is minerals that also have varying amounts of plant nutrients such as potassium, calcium, magnesium, iron, etc. Clay is the smallest soil type. Clay in the soil in large amounts makes for harder plowing, and poorer drainage, but it does assure good water holding capacity.

Think back to your experiment with the three types of Soil. 

Through what type of soil did the water drain fastest?

Discuss and explore the picture below.

Interesting Facts About Soil

A soil's mixture of sand, silt, and clay has a big influence on its use because it's mixture affects physical condition, water-holding capacity, drainage, erosion potential, and soil fertility.   Soil mixture usually varies with depth.  Topsoil usually contains large amounts of sand, silt, and minerals. Subsoil usually contains more clay. Their are five soil-forming factors: time, climate, parent material, biology and topography. It takes approximately a year to form a layer of soil as thick as a sheet of paper!  Because of this, a single rainstorm can wash away a hundred year's worth of soil formation.  (This makes it very important to protect the soil we have!)

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