Cation Exchange Capacity in Soils, Simplified - The Ideal Soil 2014 - page 33

Burma and the United Kingdom (as of 2010, the acre is no longer officially used in
the United Kingdom, though is still used in real estate descriptions). It is also still
used, to a large extent, in Canada.
An average home vegetable garden is around 25 ft x 40 ft = 1000 ft 2 . There are
43.56 1000 ft 2 sections in an acre . To convert lbs/acre into lbs/1000 ft 2 , divide
lbs/acre by 43.56.
Web Links in Hardcopy and Ebook
Letters that are grey-colored or underlined in the hardcopy version of The Ideal
Soil are URL links to websites or to other pages in The Ideal Soil in the ebook
version .
meq/100g vs cmol c /kg
The accepted modern notation for scientific audiences is cmol c /kg (centimoles of
charge per kg soil). The “c” subscript before the slash in cmol c /kg denotes
“charge”. The magnitude of the numbers remains the same. 10meq/100g = 10
cmol c /kg. Many soil testing laboratories still use meq/100g, and we will be using
meq/100g in this topic because that is the notation used byAlbrecht and what will
be found in the older research that much of our knowledge of exchange capacity
is based on.
Capitalization of Names of Elements
The names of the elements are capitalized in this topic. The various chemistry
terms that refer to their combination with other elements are not capitalized; e.g.
Sulfur in Sulfur trioxide SO 3 will be capitalized; sulfate in Magnesium sulfate
MgSO 4 will not be capitalized because sulfate refers to the SO 4 molecule, not the
pure element S.
Primary, Secondary, and Micro Elements
The common English agronomic terms Major, Minor, and Trace elements can be
confusing because they don't accurately describe either the importance or the
relative amounts of the element in the soil or the plant. Neither do they translate
easily into some languages or retain the same meaning when translated as they
do in English.
Another common usage is Macro- Micro- and Trace elements, which is not much
better than Major and Minor. Using the prefixes Macro- Meso- (middle, medium)
and Micro was considered but rejected because it would entail introducing “meso”,
a term not in common usage in many languages.
In the event, this topic will use the terms Primary , Secondary , and Micro to
describe and rank mineral elements in a general way by their required amounts
in the soil and percentage occurrence in the crops grown. Primary , Secondary ,
and Micro are not meant to reflect the relative importance of an element in the
health of living things, but only their approximate ratio of abundance in a fertile,
balanced soil.