Soil Structure

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Soil Structure

• Prepared by
• Eric Johannesen
• Iowa-Grant High School

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What is soil Structure?

• Soil structure describes the arrangement of the
  solid parts of the soil and of the pore space
  located between them
• It is dependent on what the soil developed from
  the environmental conditions under which the soil
  formed the clay present, the organic materials
  present and the recent history of management

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Soil Structure
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Granular Soil Structure

• In the granular structure, the structural units
  are approximately spherical and are bounded by
  curved or very irregular faces that are not casts
  of adjoining peds. In other words, they look like
  cookie crumbs
• Commonly found in the grassland regions of the
  United States

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Blocky Soil Structure

• In blocky structure, the structural units are
  blocklike
• The structure is described as angular blocky if
  the faces intersect at relatively sharp angles

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Platy Soil Structure

• In platy structure, the units are flat and
  platelike.
• Platy structure tends to impede the downward
  movement of water and plant roots through the
  soil.
• Usually found in the C and B horizon.

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Prismatic Soil Structure

• In the prismatic structure, the individual units
  are bounded by flat to rounded vertical faces.
• The vertical cracks result from freezing and
  thawing and wetting and drying as well as the
  downward movement of water and roots.
• Usually found in the B horizon.

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Columnar Soil Structure

• In the columnar structure, the units are similar
  to prisms and are bounded by flat or slightly
  rounded vertical faces
• The tops of columns, in contrast to those of
  prisms, are very distinct and normally rounded

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Structureless Soil Formation

• Some soils lack structure and are referred to as
  structureless