Soil moisture, percent organic matter and soil texture calculations

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Soil moisture, percent organic matter and soil
texture calculations
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Soil Moisture Procedures

• 1. Weigh the soil when it is taken out of the
  ground.
• 2. Dry it in the oven.
• 3. Weigh the soil after it is dry.
• 4. Consider drying the soil more and reweighing
  the soil to be sure it is dry.

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Soil moisture calculation

• Percent moisture mass water x 100
• mass original soil

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Calculate the percent of soil moisture

• Masses of soil and the pan -0/.01
• Mass of original soil pan 180.00
• Mass of dry soil pan 150.00
• Mass of empty pan 20.00

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Percent water

• Percent water
• 30.00/160.00 x 100
• 19

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Percent organic matter in the soil

• Grind dry soil into small particles
• Put a sample into a crucible
• Weigh the crucible and the soil
• Heat to burn the soil
• Let it cool
• Weigh the crucible and the soil
• Heat the crucible and the soil
• Let it cool
• Reweigh
• Repeat until the mass no longer change

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Percent Organic Matter
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Percent Organic Matter

• Why must the soil be dry before heating?
• Why is the soil heated in a crucible?
• Will the mass of the soil increase or decrease?

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Percent organic

• Why does the soil need to be heated repeatedly
  until the mass no longer changes?

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Percent organic equation

• Percent organic
• mass organic matter x 100
• mass of original, dry soil

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Percent organic calculation

• Masses of crucible and soil 0.01 g
• Mass of crucible and soil 25.00
• Mass after first heating 23.50
• Mass after second heating 23.00
• Mass after third heating 23.00
• Mass of dry empty crucible 5.00

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Percent organic calculation

• Percent organic 2.00/20.00 x 100
  10.0 organic matter

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Soil Texture

• Soil texture depends on the amounts of sand, silt
  and clay.
• Sand is the largest type of particle
• Silt is intermediate in size
• Clay is the smallest

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Soil texture

• Soil texture depends on the amount of sand, silt
  and clay in the soil.
• Size description Diameter in mm
• Clay lt0.002
• Silt 0.002-0.06
• Sand 0.06-2

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Compare
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Soil terms

• Porosity The percentage of space that is empty,
  this affects the aeration and the oxygen content.
  

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Soil Permeability The ability of water to flow
through soil.
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Water holding capacity the ability of the soil
to hold water

• Clay stores too much water
• Sand does not hold water very well

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Water logging Clay soils easily become water
logged
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Water logged field
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Workability Workable soil is good for
agriculture and gardens
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Compare
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Soil terms

• Water logging When the soil becomes too wet
• Plants can die from growing in water logged soils
• Clay soils can become waterlogged easily.

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Compare sand, silt, clay

• Which is the most porous?
• Which has the highest water-holding capacity?
• Which is the most permeable?
• Which has the best drainage?
• Which has the most air space?

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Loam Soil

• Loam soil is a mixture of sand, silt and clay
• It is good for agriculture because it has a range
  of properties from all of the particle types.

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Loam

• A mixture of 40 sand, 40 silt and 20 clay

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Soil Texture
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Soil texture calculations Percent sand
15 Percent silt 60 Percent clay
25 Determine the soil texture Silty Clay
Loam
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Soil Texture calculations Percent sand
70 Percent silt 20 Percent clay 10 Determine
the texture of the soil.
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Soil Texture calculations Percent sand
70 Percent silt 20 Percent clay 10 Determine
the texture of the soil.
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Soil Texture calculations Percent sand
70 Percent silt 20 Percent clay 10 Determine
the texture of the soil.
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Soil Texture calculations Percent sand
70 Percent silt 20 Percent clay 10 Determine
the texture of the soil. Sandy loam
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Sandy Loam
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Soil texture calculations Percent sand
20 Percent silt 30 Percent clay
50 Determine the soil texture
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Soil texture calculations Percent sand
20 Percent silt 30 Percent clay
50 Determine the soil texture
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Soil texture calculations Percent sand
20 Percent silt 30 Percent clay
50 Determine the soil texture
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Soil texture calculations Percent sand
20 Percent silt 30 Percent clay
50 Determine the soil texture Clay
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Clay Soil
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Properties of clay, sand, silt and loam
texture nutrients Water flow Water holding Aeration workability
clay good poor Good (too much?) poor poor
silt medium medium medium medium medium
sand poor good poor good medium
loam medium medium medium medium Best