Ed Golson Outdoor Education

soil types

What is soil?  Soil is the thin layer of material near the surface of the earth that holds the plant roots.  The materials that make the soil up are weathered rocks and decayed matter.  Soil is formed over a long period of time by a process called weathering.   

Types of soil:  The Earth is made up of a variety of soils.  The main ones are: sand, clay, silt, loam, and peat.  These materials are classified by the size of their particles.

Sand - Sand is made up of the largest particles, .06 to 2 mm in diameter.  Sand feels rough when rubbed.  Weathered granite and other rocks containing large amounts of quartz form sandy soils.  Generally, sand consists of small quartz grains.  This type of soil holds very little nutrients unless it is mixed with organic materials.  Well aerated, light, and good for drainage makes this type of soil easy to work with.  Another benefit of this type of soil is that it warms up quickly.  With proper maintenance, this type of soil can be very productive.

Silt - This type of soil has particles that are between the size of sand and clay, between .002 to .06 mm in diameter.  Silt particles are too small to easily be seen, but give a gritty feel to the soil.  Currents often carry silt along riverbeds and deposit it on soils near riverbanks. 

Clay - This type of soil is made up of the smallest particles, less than .002 mm in diameter.  Soils containing large amounts of clay are weathered from parent rock that is rich in feldspar.   The particles that make it up are very small and close together making it a heavy soil. This does not allow plant roots to push through it and grow easily, and it also prevents water and air from getting to the roots.  

Loam - This is a mixture of sand, clay, and organic material that are found in fairly equal amounts.  This soil is a good choice if you need a balance of nutrients and drainage.

Peat - This type of soil is made from decomposed organic material.  It only forms under certain conditions in wet areas. This soil is very fertile and nutrient rich, and is the best natural soil Earth has for growing a wide variety of plants. 


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