When we decide how to manage our gardens we can take steps to
imitate dryland soils by keeping potassium levels lower while
maintaining higher levels of calcium.
Now take another close look at the third chart. Average vegetation
from dryland soils contains slightly more potassium than calcium
(1.2:1) while average vegetation from wetland soils contains many
more times more potassium than calcium (4.5:1). When we import
manure or vegetation into our garden or farm soils we are adding
large quantities of potassium. Those of us living in rainy climates
that were naturally forested have it much worse in this respect than
those of us gardening on the prairies or growing irrigated gardens
in desert climates because the very vegetation and manure we use to
"build up" our gardens contains much more potassium while most of
our soils already contain all we need and then some.
It should be clear to you now why some organic gardeners receive the
soil tests like the man at my lecture. Even the soil tester,
although scientifically trained and university educated, did not
appreciate the actual source of the potassium overdose. The tester
concluded it must have been wood ashes when actually the potassium
came from organic matter itself.
I conclude that organic matter is somewhat dangerous stuff whose use
should be limited to the amount needed to maintain basic soil tilth
and a healthy, complex soil ecology.