Water - the key to healthy plants
In many cases natural rainfall is variable
and cannot provide the soil and the living creatures within the
soil with a continuous supply of water. We try and solve this by
irrigation, typically by applying water from above.
However there are some intrinsic problems.
First is knowing how much water to apply.
If we apply water for a short period of time we only wet the
surface so the water quickly dries up with little benefit to the
plant and soil creatures. If we apply water for too long the
water will pass beyond the root zone, this wastes water but also
flushes valuable nutrients from the soil often causing pollution
of the river system.
Second it the amount of water retained in
the soil is really very small. Soil is generally made up from
particles with a wide range in sizes. The large particles exert
only very small capillary action so the water just passes
straight through. The amount of water which is held after the
soil has drained is called the field capacity.
On the other hand the very small particles
exert very high capillary forces, so high that the plant cannot
extract the water from the soil.
This is called the wilt point.
The water actually available to the plant it the
difference between the field capacity and the wilt point.
This is called the available water.
While the actual values vary widely, for
example clay has very high field capacity and wilt point while
sand has very low field capacity and wilt point the difference
between these two values, the available water is small typically
only 10% of the total volume of the soil.
Even worse is that the growth to the plants will slow as
they find it more difficult to extract the water so the useful
water or readily available water is even less, may be only 5% of
the soil volume.
The wicking bed™ system
The basic wicking bed system works in its
most basic consist of a barrier to the water escaping deep into
the soil, this can be made by digging a hole and lining with a
plastic sheet or a bucket. Another version is to have a
conventional planter pot but instead of having drainage holes in
the base it has the drain hole in the side so water accumulated
in the base of the planter pot.
It works by preventing the water draining
away from the soil, so it becomes saturate rather than at field
capacity. The amount of water in the soil at saturation, when
all the large holes are filled with water is much higher than
field capacity, it could be as much as double the field capacity
is a well aerated soil, and as the available water is the amount
of water above the wilt point the increase in water holding
capacity is significant – multiples of a conventional free
draining soil.
Despite being so simple they are very
effective, more sophisticated versions can be made with pipe
work to distribute the water or an inverted container (with
bleed hole) to store the water.
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Not
just water
The motivation for the development the
wicking bed system is much more than saving time between
watering for the home grower.
Our modern agricultural system is extremely
efficient in providing us with high calorie high sugar, high fat
diet. This diet is often poor in mineral, trace elements and
nutrition. This is leading to what is called the diseases of
affluence, obesity, diabetes, heart problem and cancer.
Modern agriculture relies heavily on
fertilisers, often chemically based which provides ample of the
basic plants needs of N,P,K.
There is typically enough of the trace elements in the
soil to ensure the plants look healthy, but we as animals need
much higher concentration of these minerals, some ten times that
of plants.
There are a number of steps in the process
of us receiving this balance to our diet.
First there must the basic minerals and trace elements in
the soil. These can
be readily added to the soils, there are mines which crush rocks
containing these minerals. However
these are insoluble and need the action of soil bacteria to
break them down so they can be absorbed by plants
Plants produce a wide range of
phytochemical (plant based chemicals ) which are particularly
beneficial to health.
A tomato has some ten thousand different chemicals.
However the beneficial soil organism such
as the fungi can only flourish with consistent moisture. Part of
the benefit of the wicking bed is a simple way of extending time
between watering but the major advantage is providing the
consistent moisture for the soil biology so we can grow plants
high in nutrients.
The simple wicking box, enables virtually
anyone even with a window box or veranda to grow at least a
limited supply of nutrient rich vegetables or herbs to restore
balance to their diet.
Wicking beds may be simple, easy to make and use, but there
success lies in the soil. Read more
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