Teaching Organic Farming and Gardening

Soil Physical Properties

Unit 2.1 | 33
Supplemental Demonstrations

Supplemental Demonstrations and Examples

for the instructor

Instructor overvIew

These demonstrations and examples use

analogy and models to illustrate various

soil physical properties. Note the references

to sections of the detailed lecture outline for

specific topics.

soIl exaMPles

Lecture Outline Reference:  Throughout

PUrPOSE

To  show    examples    of  certain soil    physical    prop-

erties

MATErIAlS: ExAMPlES OF SOIl TO ShOw

• Color (dark = high organic matter, bright = well

drained, redoximorphic features = wetness)

• Structure

• Texture (sand, silt, clay, loam, etc.)

• Hard pans

Baklava DeMonstratIon

Detailed    Lecture Outline Reference:  C   1   a)  iii 

PUrPOSE

To  show    layering    akin    to  what    is  found   in  phyl-

losilicate  (layer-lattice) clays

MATErIAlS

•    Baklava,   preferably  enough  so  that    each    student 

can have    a   piece

METhODS

Point   out that    many    clay    minerals    are layered at  

the microscopic level   much    the way that    baklava 

is  and that    cations are adsorbed    to  the sides   

of  clay    particles   much    the same    as  the nuts    are 

stuck   to  the sides   of  the baklava.

MoDels DeMonstratIon

Detailed    Lecture Outline Reference:  C   1   a)  iii 

PUrPOSE

To  show    the arrangement of  molecules   in  silica  

tetrahedra  and alumina dioctehedra

MATErIAlS

•    Molecular  models  or  models  made    from    

cardboard   and tape    showing the shape   of  a   

tetrahedron and octrahedron

METhODS

If  short   on  time,   skip    this.   This    is  more    than    

many    can comprehend  but I   use it  to  illustrate  

the complexity  of  the clay    minerals.