Agriculture Reference
In-Depth Information
food crops in all climates. Version 1.0 was assembled in 2005; the first published
version was v 1.8 in 2008. The present version 2.0 has only a few minor
changes and refinements from v 1.8; it may be used with confidence.
Everything on the chart is related to everything else based on the Cation
Exchange Capacity (CEC) of the soil you are working with. Because of that, the
starting point is a reliable estimate of the soil's CEC, percent of saturation of that
CEC with the base cations Calcium, Magnesium, Potassium and Sodium, and the
ratio of those cations to each other.
The first step is to
get a professional laboratory soil test
. One really should
have a soil test before adding any minerals at all. You need to know what you are
starting with.
The recommended soil test for balancing minerals according to the Ideal Soil
method is
the Mehlich 3 test
. The Mehlich 3 or M3 soil test is a strong acid (pH
2.5) extraction. It will measure not only the minerals that are readily available, but
also those that are potentially available, the reserves. The Mehlich 3 test is
available from most modern soil testing labs.
Two other soil tests are in common use around the world, the
Ammonium
Acetate 7.0 pH
test and the
Morgan or Modified Morgan
test.
Although it is useful for measuring readily available nutrients, due to the higher pH
(4.8) of the Morgan extracting solution, the
Morgan test results
are not suitable
for estimating CEC or balancing the Base Cation Saturation Ratios, nor does the
Morgan solution extract sufficient Phosphorus, Iron, Manganese, Copper, or Zinc
to give an accurate assessment of the soil reserves.
For soils of pH 7 and below, the
Ammonium Acetate pH 7.0
test will give a good
estimate of CEC and the Base Cation Saturation Ratios, but like the Morgan tests,
theAA7.0 pH solution does not extract enough of the secondary minerals to
accurately show soil reserves.
For best results, you want a Mehlich 3 soil test with amounts in parts per million
ppm for all of these mineral elements:
Primary Cations
PrimaryAnions
Secondary Elements
Calcium
Magnesium
Potassium
Sodium
Phosphorus
Sulfur
Boron
Iron
Manganese
Copper
Zinc
These are minerals whose function we understand well and it is essential that they
all be in your soil in sufficient quantities. You do not need to know the amounts of
