Agriculture Reference
In-Depth Information
Chapter 3
Balancing the Cation Nutrients
Calcium Ca++, Magnesium Mg++, Potassium K+ and Sodium
Na+
Please read the previous section “Conventions Used in This topic”, especially the
part about
parts per million
. We will be working with ppm in the next 4 chapters.
The soil is the storehouse of fertility, or at least it should be. The minerals that the
plants need in order to grow and reproduce another healthy generation all come
from the soil and are stored there, in or on one of the following forms:
•
The clay fraction
•
The organic fraction: both living and dead/decaying
•
Rock minerals of various sizes and types, from silt to boulders
•
The soil/water solution: dissolved nutrients, easily available, also easily
leached out.
The storehouse capacity we are concerned with right now is a property of the first
two items on the list, the
clay
and
organic
fractions. The soil/water solution and
the rocks are not considered part of the exchange capacity.
What we wish to do is to load the storehouse up with the mineral nutrients in the
proper balance. This will accomplish a number of things:
•
On a physical level, it will keep the soil loose and friable so air, water, plant
roots and soil organisms can move through it freely
•
On the level of chemistry, it will allow the acid/alkaline balance, the pH, to
self adjust, ideally to around pH 6.4.ApH of 6.4 is where the maximum
amount of nutrients are available.
•
By having the proper balance of cation nutrients filling the exchange sites,
those nutrients will be readily available to the plant roots and soil organisms,
so they can “trade” Hydrogen H+ ions for the nutrients they need.
•
When the cation nutrients are held to the soil colloids (clay and humus) they
are not subject to leaching or washing away due to rainfall or irrigation.
