Hydroponics Gardening Facts
The History of
Hydroponics
As seen in Growing Edge Magazine
Hydroponics basically means working water ("hydro" means
"water" and "ponos" means
"labor"). Many different civilizations have utilized
hydroponic growing techniques throughout
history. As noted in Hydroponic Food Production (Fifth
Edition, Woodbridge Press, 1997, page
23) by Howard M. Resh: "The hanging gardens of Babylon,
the floating gardens of the Aztecs
of Mexico and those of the Chinese are examples of 'Hydroponic'
culture. Egyptian hieroglyphic
records dating back several hundred years B.C. describe
the growing of plants in water."
Hydroponics is hardly a new method of growing plants.
However, giant strides have been
made over the years in this innovative area of
agriculture.
Throughout the last century, scientists and
horticulturists experimented with different methods
of hydroponics. One of the potential applications of
hydroponics that drove research was for
growing fresh produce in nonarable areas of the world.
It is a simple fact that some people
cannot grow in the soil in their area (if there is even
any soil at all). This application of
hydroponics was tested during World War II. Troops
stationed on nonarable islands in the
Pacific were supplied with fresh produce grown in
locally established hydroponic systems.
Later in the century, hydroponics was integrated into
the space program. As NASA considered
the practicalities of locating a society on another
plant or the Earth's moon, hydroponics easily
fit into their sustainability plans. This research is
ongoing.
But by the 1970s, it wasn't just scientists and analysts
who were involved in hydroponics.
Traditional farmers and eager hobbyists began to be
attracted to the virtues of hydroponic
growing. A few of the positive aspects of hydroponics
include:
• The ability to produce higher yields than traditional,
soil-based agriculture
• Allowing food to be grown and consumed in areas of the
world that cannot support
crops in the soil
• Eliminating the need for massive pesticide use
(considering most pests live in the
soil), effectively making our air, water, soil, and food
cleaner
Commercial growers are flocking to hydroponics like
never before. The ideals surrounding
these growing techniques touch on subjects that most
people care about, such as helping end
world hunger and making the world cleaner. In addition
to the extensive research that is going
on, everyday people from all over the world have been
building (or purchasing) their own
systems to grow great-tasting, fresh food for their
family and friends. Educators are realizing
the amazing applications that hydroponics can have in
the classroom. And ambitious individuals are striving to make their dreams come true
by making their living in their
backyard greenhouse, selling their produce to local
markets and restaurants.
And now that so many people from so many different walks
of life are involved in hydroponics
and its associated disciplines (such as aeroponics and
aquaponics), progress is coming faster than ever before.
Aero-Hydroponics
The Method of the Future
by Lawrence L. Brooke
A Brief History
The aero-hydroponic method was developed in Israel in the
early 1980's. Dr. Hillel Soffer,
senior researcher at the Volcani Institute at Ein Gedi
developed the aero-hydroponic method
to overcome the challenges presented by the hot, arid
conditions at Ein Gedi. The discoveries
that followed the development of aero-hydroponics offer
great benefits to all hydroponic
growers.
During a two-year period from 1986 to 1988, Dr. Soffer
performed extensive research using
the aero-hydroponic method at the University of California
at Davis, where he had received his
Ph.D. in the early 1970s. The specific area of research was
in quantifying the effect of various
levels of dissolved oxygen on root growth, especially in the
propagation of plants from
cuttings.
The findings of his research were published in the Journal
of the American Society for
Horticultural Science, and HortScience. Both studies were
co-authored with David Burger at
UCD. In addition, Dr. Soffer presented his findings at the
annual conference of the Hydroponic
Society of America in 1988.
Except for the papers mentioned above, very little has been
printed up to now on the aerohydroponic
method. The method was patented internationally, though few
licenses for the
production of equipment have been granted. Without
aggressive commercial support, the
aero-hydroponic method has remained largely a research tool,
known mostly to university
researchers.In the meantime, the rockwool method was
becoming available internationally
following 12 years of exhaustive research and a strong
marketing program with lots of
investment in advertising, production and distribution,
first in Europe and later in Japan.
Following nearly a decade of rockwool use, the Dutch
contacted Dr. Soffer to request
permission to develop and use the aero- hydroponic method.
The reason for the sudden
interest of the Dutch in the aero-hydroponic method has
implications for the development of
hydroponic cultivation worldwide.
For rockwool cultivation to work efficiently in most
commercial operations it is preferred to a
use a non-recirculating nutrient solution. Nutrient solution
is sent on a one-way trip through
the rockwool and is then discarded. The real cost advantage
of rockwool cultivation over other
hydroponic methods was that the nutrient did not have to be
recaptured and recirculated,
reducing the system complexity of reservoirs, plumbing,
pumps and pH and conductivity
controllers. The once-through nutrient system also reduces
the problem of nutrient solution
becoming imbalanced due to erratic uptake of minerals by
rapidly growing plants; plus the
build up of dissolved minerals from slowly dissolving
rockwool.
The discharge of enormous amounts of spent nutrient solution
has become a major problem
in Holland, contaminating surface and ground waters.
Consequently, the Dutch government
has prohibited the dumping of nutrients resulting in renewed
interest in recirculating systems
such as aero-hydroponics.
As leaders in both horticulture and commercial hydroponics,
the Dutch have recognized the
value of a method, which enables rapid and trouble-free
cultivation and eliminates the
problems of disposing of spent nutrients and exhausted
media.
The Aero-hydroponic Method
Aero-hydroponics is not a simple method to understand. The
equipment required is
somewhat more complicated than other hydroponic methods, but
there is a great advantage in
that once an aero-hydroponic system is set up, it will run
almost indefinitely without additional
investment in such disposable components as growing media
and non-recalculating nutrients.
What is most surprising about aero-hydroponics is not how it
works, but why plants grow
better. The key is dissolved oxygen at the root boundary
zone.
The essence of Dr. Soffer's work at UCD was in quantifying
root growth in proportion to
dissolved oxygen. Only the green parts of the plant can form
oxygen from carbon dioxide
roots require a supply of oxygen for metabolism and growth.
Plant growth in oxygen deficient
conditions, such as those found in many soils, is limited.
Dr. Soffer found the enhanced
oxygen at the root zone produced enhanced growth.
In aero-hydroponics, the nutrient solution is sprayed
through the air in order to infuse the
nutrient with dissolved oxygen. The method differs from
classic aeroponics in that most of the
plant's roots are not suspended in air and fed by a spray of
nutrient solution; rather, the
majority of the roots are submerged in oxygen-infused
nutrient which is in constant motion in
order t maintain high levels of dissolved oxygen at the root
boundary zone where oxygen and
nutrients are taken in by the plant.
The result is a propagating tool of unsurpassed performance.
Dr. Soffer was successful in
propagating plant varieties at UCD that had never been
propagated before. He took particular
delight in propagating varieties of conifers and even
pistachio trees (pistachio cuttings
required 90 days to generate roots). Moreover, he found that
cuttings could be rooted aerohydroponically
in purified water without using rooting hormones such as IBA
or NAA. This is
because plant tissue already contains the natural rooting
hormone IAA (Indole Acetic Acid).
Aero-hydroponic Systems.
Aero-hydroponic systems can be built using quite a variety
of materials and in numerous
design configurations. The Ein Gedi "Mini Unit" which was
used at UCD for dissolved oxygen
studies is a stand-alone module which supports four plants
in 10 liters of nutrient solution.
An electric motor mounted on the top of the unit spins a
nutrient sprayer, which lifts nutrient
solution and sprays it onto the "aerial roots."
Additionally, the rotation causes the nutrient
within the unit to stir, moving it constantly over the
submerged roots.
Large-scale aero-hydroponic systems follow the design of the commercial installation at Ein
Gedi. These commercial systems consist of "canals" or
growing chambers with plant sites on
top. A pump provides the pressure to drive a system of
sprayers to supply the aerial roots,
while the submerged roots hang into the flowing nutrient in
the canal.
Both of these systems share fundamental characteristics,
which define the aero-hydroponic
method. The plants are supported above the flowing nutrient.
The roots hang down through an air gap in which nutrient is sprayed, then into the moving nutrient
solution below the air gap.
The nutrient sprayed through the air gap is not so much
intended to feed the plant, but rather
to infuse oxygen into the nutrient solution wherein the
feeder roots remain constantly
submerged. It is these submerged roots in oxygen rich
nutrient that provides most of the
nutrition and oxygen for the plant.
Home Installation
The AeroFlo system is designed and built by General
Hydroponics following the Aerohydroponic
method. It consists of a reservoir placed below the growing
chambers, which
support the plants. The nutrient in this system is changed
every two weeks and the pH is
adjusted to 5.5 to 6.5 and nutrient conductivity is
maintained at about 800 to 1200 ppm.
Since there is no growing medium except a handful of "GROROX"
at each plant site, pH
remains very stable and only requires an initial adjustment
when mixing fresh nutrient, if the
water supply is of good quality.
The AERO-HYDROPONIC METHOD is without doubt the most
advanced hydroponic method
that has been developed to date. The cost of constructing
and installing systems, plus the
complications of obtaining licensing, have been deterrents
to widespread commercial
application. This is changing as commercial growers,
researchers, serious hydroponic
gardeners and manufacturers become aware of the capabilities
and value of aero-hydroponics.
Lawrence L. Brooke is the owner and founder of General
Hydroponics in Sebastopol,
California
Originally published in The Growing Edge, Vol 2, No 1, Fall
1990
The debate on "Organics" and "Hydroponics"
There is a huge popular debate about the value of "organic"
fertilizers and methods, many people would like to apply
"organics" to hydroponics. Currently accepted organic
fertilizer
components are dependent upon organisms in the soil to
convert
the "organic" materials into a useable form for plants.
In hydroponics we provide the minerals required for plant
growth
directly, completely eliminating the need for soil and
soilorganisms.
The result is much higher growth rates, yields and even
crop quality than organic methods can achieve. This is not
what
some people want to hear, but it is the simple scientific
truth - and
practically all scientists and educators in the fields of
agriculture
and chemistry know it and will be the first to agree. In
fact, the
kinds of materials which are permitted for use under
"organic"
regulations are not of sufficient purity to be used for
hydroponic
culture.
With this in mind it's important to recognize the reasons
that
"organically" grown produce is gaining such popularity.
Consumers want to buy produce which is not tainted with
hazardous chemicals or poisons. There is an increasing
public
demand for methods which are gentle on our delicate planet
and
which don't harm the soil, water or ecosystems. Hydroponic
farming methods fit properly into this system of values if
used
appropriately. Hydroponics protects soil because it doesn't
use soil.
Less water is required for hydroponic culture and
consequently
more food can be cultivated with less water. The fertilizers
we use
for hydroponics are ultra-pure and leave no residue in the
cultivated fruits and vegetables. Since hydroponic
technologies are
more efficient than soil methods, more people can be fed
with less
area and ecological impact.
THE ORGANIC HYDROPONIC DEBATE OPENING
PANDORA'S BOX
As seen in the Growing Edge Magazine
During the 1980’s, Americans increasingly became more
health conscious.
Cholesterol was ruled out and exercise became a part of
our daily routines. Today this still holds true, but even
more so.
What we put into our bodies is carefully scrutinized, even
our
fruits and vegetables, which has made “organic” a buzzword
of the
‘90s. People are buying organic skin care products, “organic
shampoos” and even "organic clothing”. Everybody seems to
want
“organic” and hydroponic growers are quite aware of this.
Why,
then, are there hardly any "Certified Organic hydroponic
growers”
in the United States? Many go through a great deal of
trouble to
grow their crops "organically," but even though they follow
most
guidelines, they still cannot get the recognition or
certification
necessary to sell their produce to most restaurants or
natural food
stores as “organic”. What is it that is separating organic
from
hydroponic methods? Why can't these two technologies work
together under today's American states' certification
guidelines?
WHAT'S ORGANIC, WHAT'S NOT?
We would think that this is an easy question to answer, but
it isn't.
In the United States there are numerous different
definitions of
"organic", many of which differ significantly. Each state
has its
own regulations for labeling produce as “organic".
Additionally,
there are 36 non-governmental organizations which can
certify"
produce as organic. For example, California growers who wish
to
sell their produce as "organic" must register with the
California
Department of Food and Agriculture and pass their
inspection.
However, California grower's can also obtain certification
through
the California Certified Organic Farmers (CCOF), which
actually
has higher standards for organic than the state has.
The CCOF certification is optional, but produce with
California
state registration and CCOF certification may be offered for
sale
within the state as "certified organic" If the grower
chooses not to
seek CCOF certification, the produce can be offered for sale
in
California as "organic," but not "certified organic”. Any
produce
grown outside of the United States can be sold as "certified
organic" in the country if one of the 36 non-governmental
organizations certifies it. In fact, produce from any state
can be
granted certification from one of the non-governmental
organizations, even if it does not meet the organic
standards for the
state in which it is being sold. Pretty confusing!
What this all means is that the "organic" label is a matter
of
bureaucratic definitions, which can vary from state to
state, and
country to country.
In order to bring some kind of standard into play, the U.S.
Department of Agriculture (USDA) – along with state
government
regulators, non-governmental certifiers, consumers, industry
interest groups, food processors and various special
interest groups
– is writing a federally mandated set of "organic"
standards. No
state will be able to apply more stringent standards than
those of
the federal. Sometime this spring, the federal standards
will be
released for a 90 day comment and review period, and by the
end
of 1996 or early 1997, these standards will become law, or
"Frankenlaw"; we'll have to wait and see.
The basic objectives of "organic" practice include the
following:
• Avoidance of pesticides, by use of natural pest controls
(also
applied by many hydroponics growers).
• Caring for soil by recording nutrients and composting, and
• Moderation of nutrient application with reliance on the
buffer
action of humus derived from compost.
Soilless hydroponic cultivation moderates nutrient supply by
the
more exact measurements of soluble nutrient formulations,
mixed
to meet the optimum requirements of each plant species and
growth phase. Many consumers select "organic" produce,
believing that this is the only way to be assured of
pesticide-free
non—hazardous food. While "organic" farming methods do
produce crops generally superior to and safer than those
grown by
agri-business practices, modern hydroponic techniques can
put
forth equally safe food that in many cases offers advances
in
nutrition and taste over their soil-grown “organic”
counterparts.
But to the consumer, it's the label that counts, so an
increasing
number of growers throughout the United States are
struggling to
get organic certification in any way, shape or form.
Meanwhile, this whole situation poses an enormous dilemma to
hydroponic growers who also want organic recognition for
their
produce. The primary problem for organic hydroponic growers
is
in the formulation of the soilless nutrient solution. A
secondary
issue, which concerns the federal regulators, is in the way
used
hydroponic nutrient and media such as rockwool are disposed
of.
Since "organic" is to a large extent a farming philosophy in
support
of a healthy environment, the federal concern is entirely
reasonable.
Although the latter factor has no bearing on the quality and
safety
of the produce itself, the impact upon the planet is a real
driving
force behind the issue of "organic" farming. If hydroponic
growers
can find a way to completely recycle exhausted water,
nutrients
and media, then the argument in favor of "organic-hydroponic
certification" becomes much stronger, but there's still the
issue of
formulating a satisfactory organic hydroponic nutrient mix.
Organic nutrient regulations prohibit the use of many
mineral salts
and highly refined substances, including food and
pharmaceutical
grade ingredients that are extremely important for
successful
hydroponic nutrient formulation.
Only unrefined minerals can be used on "organic" crops and
these
often don't dissolve well or contain quantities of
impurities, some
of which are even relatively toxic but are "natural” and
therefore
“okay”, according to organic standards. For example, mined
phosphate may contain excessive amounts of fluoride, good
for
teeth in very small quantities, but harmful to humans in
excess.
Mined phosphate also can contain small amounts of
radioactive
elements such as radium, which releases radon, also not good
for
human health. Chlorides, too, are permitted for organic
cultivation
but though they are naturally mined, they can be bad for
both
plants and soil, especially if used in excess. Some soils
used by
organic farmers contain such toxic elements as selenium,
which
can accumulate in the plant tissues and produce. Amazing,
isn't it?
When refined, any impurities or toxicities such as those
listed
above are removed, but refined minerals make for non-organic
produce. Blood meal, bone meal, fish meal and manures pose
almost no potential safety hazards, but they don't dissolve
very
well; they must be broken down through microbial action in
the
soil and therefore don't work well in hydroponic
applications.
There is also a problem that sometimes arises when using
manures.
The Western Fertilizer Handbook, an important guide for
American farmers, points out that many gastro-intestinal
illnesses
can he traced back to manures used on organically gown
crops. In
the summer of 1995, a serious outbreak of salmonella
poisoning
resulted from an organic cantaloupe crop growing in soil
fertilized
with fresh chicken manure. The rinds of the melons had
become
contaminated and the bacteria caused serious intestinal
illness for
many consumers.
Another point that can be made is that strict vegetarians or
animal
rights activists may be offended by the use of blood, bone,
horn,
hoof and feather meals to grow their food, but these are
primary
nutrient sources for organic farmers.
As you can see, this issue Is very complex and there are
many
points of view. Essentially though, "organic" farming is
part
philosophy and part methodology, but unfortunately defined
bureaucratically.
WHAT'S HYDROPONIC; WHAT'S NOT?
If a plant is grown without soil and with a complete
nutrient
solution, that's hydroponics! It can be as simple as plants
glowing
in sand, gravel or rockwool with a nutrient drip, or as
complex as a
complete waterculture system, such as NFT (Nutrient Film
Technique) or aeroponics.
No matter what method you use, the key to successful
hydroponics is nutrients. Hydroponic crops are raised on a
perfected mix of primary, secondary and micro-nutrients. The
formulas for different crops and environments vary, but all
have
been defined from extensive experience with a wide variety
of
crops growing in many different environments throughout the
world. Problems may occur where water quality is poor and
where
environmental extremes of high or low temperature and
humidities
place stress on crops; however, when a hydroponic facility
is
properly planned and installed, the resulting crops can be
impressive. Data generated in Europe, Israel, Canada,
Australia
and the United States have defined precise combinations of
minerals for a variety of crops. The data is so accurate
that
Courtesy of General
Hydroponics
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