!Re: A soil question

Gary Meltzer doji@hawaii.rr.com
Sat, 15 May 2010 15:45:08 PDT
Hello Dave,

>  Perhaps some of you can explain something regarding soils to me

This may confuse you thoroughly, but I'll try.

The terms relating to soil textures are based upon the relative proportions 
of the 3 basic mineral sizes making up the soil.  These terms were developed 
for use in geology and the study of land profiles They are, in descending 
order, sand, silt, and clay.   Within these groupings are subdivisions that 
are used in certain specific applications.  .  In addition, some countries 
may have different definitions of the exact size of each of these basic 
particles.  For the most part these subdivisions don't matter in our potting 
soils.  To determine a soil type by texture, the soil triangle is used.  See 
http://www3.hcs.ohio-state.edu/wiki/index.php/…   for 
an example.  Note well that these terms apply to the soil's texture based on 
the mineral content of the sample, and do not include organic matter.

In gardening both in the ground and in containers, we do add organic matter, 
and thus create "a clay soil, rich in organic matter" and other such mixes. 
The addition of organic matter will affect the texture as we describe it 
using the same terms as the geologist's soil triangle.  Therefore, (sounds 
like I know what I'm talking about, sort of) adding organic matter that has 
the sample sort of looking and feeling like the mineral definition is our 
definition.  Obviously, the size of the organic matter will alter the mix; 
pine cones and sawdust as organic additions may both be pine, but size does 

The finished soil mix does cause many chemical and mechanical things to 
happen.  Absorption and adsorption of other additions such as fertilizers or 
insecticides, perviousness  of liquids and gasses and the degree of 
retention or rejection of these, and the esthetics of the mix - "Does my 
bright orange soil really make my Clivia stand out?"

Of the many sites available under "soil triangle', one of the easiest to 
follow in my opinion is from NASA 

And, an abstract concerning porosity of soils can be read at 

I really like your upside down description, thank you for it.

Gary in Hilo, HI, zone 14 If there was a number that high, where it rains 
every day and in the winter it rains all day.   5000mm/year

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