Coconut fiber holds good levels of moisture while being highly oxygenated.
and both benefit from a disease-free and growth-promoting root
zone environment.
To achieve this balance, however, the coconut fiber substrate needs
to meet certain standards for hydroponic production. It must also
be treated in a slightly different way to other mediums and growers
need to be aware that not all coco products are created equal.
Coco fiber: some background
Coconut fiber for horticultural use has had a rather disappointing reputation in the past. In the early days, little was understood
about the properties of this organic growing medium. It was poorly
processed and had major problems with nitrogen draw down (high
levels of this means nitrogen applied to the coir in the early stages
of plant growth would not be available for plant growth, even if
full-strength nutrient was applied), high cation exchange capacity
(CEC) and retention of ions like calcium and iron, extremely high
levels of sodium and a naturally occurring potassium content that
growers did not take into account. As a result, many of the first trials
with coco fiber did not produce particularly pleasing growth results
despite the medium having almost ideal physical characteristics.
However, once the properties of this medium began to be more
understood, and processors realized the potential of the expanding
horticultural market, correct processing started to ensure we had
improved-quality coco being supplied for hydroponic use.
The coco we use in hydroponics today is processed from the outside layer (mesocarp) of coconut husks that consists mainly of coarse
tough fibers, but also contains finer material known as coir dust.
Harvested coconuts are first soaked in water (not seawater, however,
since this leaves extremely high levels of sodium in the substrate—
something which is undesirable for hydroponic use).
This process is called retting and it makes the fiber easier to remove. The longer fibers are then usually removed for other uses,
while the coir pith undergoes further processing and decomposition that makes it suitable as a plant growth medium. During
this process, the high nitrogen draw down that occurs in coconut fiber in the early stages is modified, as are excess minerals—
such as high levels of naturally occurring potassium—and the
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