Recognizing Soil Texture

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Recognizing Soil Texture Structure
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Soil Texture

• Soil texture proportions of sand, silt and clay
• Property of the soil controlled by the size of
  individual grains or particles
• Soil is usually made up of particles of widely
  varying sizes.
• Soil texture expresses the average or combined
  effect of all these grain sizes

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3 Soil Textures

• Sand
• Silt
• Clay

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Feel that soil!

• Sand In the moist condition sand should feel
  gritty and will be loose and single grained.
  Squeezed when wet, it will fall apart when the
  pressure is released
• Clay when moist is quite plastic and sticky
  when wet. When the moist soil is squeezed out
  between the thumb and fore finger, it will form
  long flexible ribbons.
• Silty Soil when dry and pulverized will feel
  soft and floury. When wet the soil readily runs
  together and puddles. When squeezed between the
  thumb and finger it will ribbon but the ribbon
  will appear checked and cracked.

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Fine Textured Soils

• Clay
• Sandy Clay
• Clay Loam
• Silty Clay
• Silty Clay Loam

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Medium Textured Soils

• Sandy Clay Loam
• Loam
• Silt Loam
• Silt

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Coarse Soils

• Sand
• Loamy Sand
• Sandy Loam

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Soil Structure

• the combination or arrangement of primary soil
  particles into secondary particles, units, or
  peds (which are separated from adjourning
  aggregates by surfaces of weakness)

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Soil Aggregation

• The cementing or binding together of several soil
  particles into a secondary unit, aggregate, or
  granule
• clods are different they are caused by some
  disturbance such as plowing or digging

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Consistence

• The resistance of a material of deformation or
  rupture the degree of cohesion or adhesion of
  the soil mass

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Structureless soil

• Soil where the particles of coarse soil fail to
  cling together, when fine soil breaks into large
  clods, or when the soil is massive, a single
  compacted substance

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Platy Structure

• Soil aggregates developed along the horizontal
  direction flaky

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Prismatic Structure

• A soil structure type with a long vertical axis
  that is prism shaped, vertical faces are well
  defined, without rounded caps

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Columnar Structure

• Vertically oriented, round-topped structural
  prisms rounded caps

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Granular Structure

• A natural soil ped or aggregate have plane or
  curved surfaces which have slight or no
  accommodation to the faces of surrounding peds

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Types of Soil Structure

• Platy
• Prismatic
• Columnar
• Angular Blocky Block-like three dimensions of
  same magnitude
• Subangular blocky same as angular except the
  vertices are more rounded
• Granular
• Crumb similar to granular except the peds are
  porous

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Class of Structure

• Size of individual ped

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Good Soil Structure

• Good Soil Structure
• Necessary for good water penetration into the
  soil
• Water holding capacity
• Ease of working the soil
• Good root penetration
• Favorable movement of soil air
• Availability of plant nutrients
• Good internal drainage

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Binding Agent in the soil

• Organic matter converted to humus is the chief
  binding agent for stable soil structure.
• Continuous cultivation and never plowing under
  any organic matter tends to destroy structure