Agriculture Reference
In-Depth Information
Our overall goal is to feed the soil and the soil organisms that in turn feed the
plants. Our specific goal is that the soil should contain perfect nutrition for the crop
we wish to grow. In the case of plants grown for food, we also want the crop to
contain all of the nutrients essential for the health of the people or animals that will
be eating the food being grown. Luckily, most food crops do best with the same soil
mineral balance.
The Calcium
:
Magnesium ratio sets the stage for all of the rest of the elements. If
the Calcium level is too high in relation to Magnesium, the soil will be loose but will
lose its texture and cohesiveness and water may drain through too easily and be
lost. It will also be more prone to erosion from wind or water. If the Magnesium
level is too high, the soil will be tight, preventing water and air from moving through
easily.
From the
Ideal Soil chart
, here is the preferred range of base saturation for most
plants:
Calcium (Ca)++ min 750ppm
60% — 85%
Optimum 68%
Ca & Mg together should add to
80% of exchange capacity in most
agricultural soils pH 7 and lower
Magnesium (Mg)++ min 100ppm 10% — 20%
Optimum 12%
Potassium (K)+ min 100ppm
2% — 5%
Optimum 4%
See Phosphorus (P)
Sodium (Na)+ min 25ppm
1% — 4%
Optimum 1.5%
Essential for humans and animals
Hydrogen (H)+
5% — 10%
Optimum 10%
Alone proton. The “free agent”
Avery heavy clay soil needs to be loosened up, so one would wish to see a Ca:Mg
saturation ratio of perhaps75% (or even more) Calcium to 10% Magnesium.Avery
loose sandy soil needs to be tightened up to hold water and prevent erosion; in that
case 60% Calcium and 20% Magnesium would be desired.
Heavy clay: 75% (or more) Calcium, 10% Magnesium
Loose sand: 60% Calcium, 20% Magnesium.
At no time do we want the Calcium saturation to be below 60% or the Magnesium
saturation below 10% unless we are growing specialty crops such as blueberries
or rhododendrons that like a high-Magnesium and somewhat acid soil or certain
plants that prefer a very high Calcium “chalky” soil.
In an “ideal” soil that has a good mix of sand, silt, and clay as well as a good level
of organic matter, ProfessorAlbrecht determined that the best ratio was 65%
Calcium to 15% Magnesium. Further experience has convinced other agronomists
that slightly different ratios work better for them.At soilminerals.com we usually
recommend a “perfect” ratio of 68% Calcium to 12% Magnesium for soils below pH
7. This seems to be the ideal proportion not only to give the plants and soil life the
