Sand

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Sand
(0.05 2 mm)
Silt
(0.002 0.005 mm)
Primary mineral particles
Clay
(lt 0.002 mm)
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12 textural classes
Textural triangle
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Loamy soils
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You can do this in your kitchen !!
Fine textured soil
Coarse textured soil
Loamy soil
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Humus and clay are the soil skin
http//www.ccma.csic.es/dpts/suelos/
Brady and Weil (2002)
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Why is the soil skin important ?

• Adsorption of water films
• Adsorption of organic and inorganic chemicals
• Ion exchange
• Catalysis of chemical reactions
• Habitat for bacteria

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Good Tilth
Poor Tilth
The soil fabric
http//www.grdc.com.au/growers/gc/gc48/conference1
.htm
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The soil pore network serves as a respiratory
and circulatory system
http//www.mtm.kuleuven.ac.be/Research/NDT/IDO_SHe
rman_final.ppt
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Pore diameter
Drainage pores
10- 30 µm
Field Capacity
Easily available
Plant available water
Permanent wilting point
0.2 µm
Hygroscopic water
Adapted from Buol (2000)
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20 yrs of bluegrass, then 5 yrs CT corn
25 yrs of CT corn
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After adding water
25 yrs of conventional corn
20 yrs of bluegrass, then 5 yrs conventional corn
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PLOW PAN 1
PLOW PAN 2
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Brady and Weil (2002)
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Intensive tillage
Long term no-till
Plow pan
Ontario Ministry of Ag and Food
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habitat !!
Soil is
The Furrow