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2.1 Physical Characteristics
Sand Particles
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Mostly quartz minerals.
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Nutrients are not held tightly to the surfaces of sand
particles, thus sandy soils hold fewer nutrients for
plants than soils composed of smaller particles.
Silt Particles
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Quartz minerals are often dominant, but unlike sand
particles, silt particles are too small to be seen without
a microscope.
Clay Particles
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Shaped like flat plates or tiny flakes that are layered.
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Collectively have a large surface area: the surface area
of one spoonful of clay is equivalent to the surface
area of a football field.
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Unlike sand and silt, clay particles are not just smaller
particles of bedrock. Clays are individual new minerals
that result from the weathering and recrystallization
of minerals and bedrock forming an entirely new
crystalline plate-like particle. The clay particles in soils
may have formed in place in the soil, or they may have
been emplaced with other sediments eroded from
other soils.