2015-01-19

#organic #hydroponics

1.18: care/agro/organic hydroponics:
summary:
. hydroponics can save water,
but it doesn't mix easily with organics;
nevertheless, organic hydroponics is possible;
furthermore, it can make use of soil microbes
that protect plants from pathogenic microbes .

"There is an increasing interest by consumers
for organically produced greenhouse vegetables,
but modern greenhouse vegetable production
has moved away from using soil
to using media such as peat, pumice or rockwool,
or even to using medium free systems such as
the nutrient film technique (NFT) or aeroponics.
The major challenge facing organic hydroponics
is to develop a satisfactory nutrient solution"
[Mike Nichols, Kim Atkins 2006].

. for an example of one failure,
an organic solution was derived from
3 parts "Betta-Crops" liquid fish
and 2 parts liquid seaweed;
the failure of the organically grown lettuce
appeared to be caused by the roots dying,
likely from a marked reduction in oxygen
due to the presence of algae
and of unbroken down organic matter
[Mike Nichols, Kim Atkins 2006].
. many algae produce oxygen during the daylight
as a by-product of photosynthesis;
but, at night, these algae consume oxygen [lsu.edu].
. even though plants create oxygen,
parts of them also require oxygen to use energy .

. for an example of success we have the
National Institute of Veg and Tea Science,
National Agricultural Research Org (NARO):
. in conventional hydroponics,
contamination of hydroponic solutions by microbes
has been regarded as detrimental,
because they compete for oxygen and nutrients
and inhibit plant growth .
. in previous studies of organic hydroponics,
inconvenient procedures have been regarded as
an integral part of the use of organic fertiliser,
and the two reactions of ammonification and nitrification
have been conducted in separate tanks
and then the resulting mineralised solution
was sterilized, and organic compounds removed .
. in the NARO method the organic compounds are
degraded to inorganic nutrients by microbes;
and it conveniently allows organic fertiliser
to be added directly to the hydroponic solution .
. the microbial ecosystem cultivated by
the organic hydroponic solution
inhibits the sort of microbes that cause root disease .
. For successful organic hydroponics,
it is necessary to establish a method of
safely mineralising organic nitrogen to nitrate-nitrogen
via ammonification and nitrification in water.
. only fertilisers with a Carbon/Nitrogen ratio
of less than 11, were able to be
mineralised to nitrate-nitrogen.
. the method is derived from knowledge about
Japanese sake fermentation
made by simultaneous multiple parallel fermentation,
saccharification by Aspergillus oryzae,
and ethanol production by yeast,
suppressing the fermentation of acetic acid.
The relationship among these reactions is similar to
that of activation of ammonification and nitrification
and suppression of denitrification.
[Nature Preceedings 2008 (see text)].