activity in the rooting medium—the degree of deficiency related to the
available nitrogen supply within the rooting medium.
A colleague and I once worked for more than two years trying to grow
greenhouse tomatoes organically, searching for organic sources of the
essential plant nutrient elements that would provide what was needed to
promote sustained plant growth and fruit yield. We were unable to find
an organic material as a source for nitrogen that would supply that level
of required nitrogen necessary to sustain plant growth and fruit yield.
We abandoned the project.
For those growing plants hydroponically, adding an organic substance
to the nutrient solution is an open invitation for the potential occurrence
of root disease. Anyone who has dealt with the root disease pythium can
attest to its occurrence being ushered in when there is an accumulation of
organic substances in the applied nutrient solution. For the grower reusing
a nutrient solution, removing the suspended organic materials by filtering,
followed by sterilization, are essential steps to prevent pythium invasion. So,
adding back an organic substance might defeat the filtering and sterilization
steps, opening the nutrient solution to disease.
Those who see the advantage in having some level of organic substances,
such as humic acid and other simila r substances, in the rooting medium
would expect to find that best plant growth should occur with the use of a
soilless organic rooting medium that contains peat moss, or other similar
substances or composts, as these materials are good sources for humic
acid and similar compounds. There is no evidence that plant growth
is enhanced when using such a rooting medium as compared to other
media. So, the question is, why would the inclusion of humic acid or other
similar substances added to a rooting medium enhance plant growth
when, occurring naturally, it doesn’t enhance plant growth?
For the organic grower, there is much that needs to be known about the
rooting medium selected and the bio-chemical characteristics of substances being recommended, pertaining to their potential benefit to plant
growth. For the soil grower, knowledge of the biological physio-chemical
characteristics of the soil needs to be present so that when additions are
made, whether organic or inorganic, one can anticipate the effects on
plant growth, either beneficial, of no effect or detrimental. Presently,
much of the talk about organics is more speculation than fact.
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Feeling overwhelmed by the buzz word organic? Be sure to ask an indoor
gardening retailer on what’s working the best for them, or ask an expert by
emailing [email protected]
Maximum Yield USA | February 2014
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