These days there is a lot of talk about one type of
alternative agriculture, the cultivation of plants out of the ground, namely
hydroponics. Our planet is 71% occupied by oceans of salt water and only the
remaining 29% is occupied by land and islands, it is therefore quite logical to
think that our resources are limited from the point of view of the space that
can be occupied , which is why research in the hydroponics field it is
increasing exponentially from year to year.
Actually this is not a sensational discovery of our times,
just think of the hanging gardens of ancient Babylon, or to the crops of the
peoples who inhabited the mountainous areas of the Andes, on Lake Titicaca
between Peru and Bolivia, who cultivated hydroponic gardens on the surface of the
water using straw pallets.
What is hydroponics
Hydroponics, i.e. cultivation without soil or without soil,
involves the adoption of alternative cultivation techniques that do not involve
the use of the soil, in its place different types of substrates are used and
with the action of water they are administered the nutrients necessary for the
growth of crops. There are actually two major types of hydroponic cultivation:
the one that uses the substrate, i.e. mixtures of perlite, sand, expanded clay,
etc., which is moistened and irrigated with water and nutrients, and the
hydroponic cultivation without substrate , where the roots of the plants are
immersed in the flow of the nutrient solution (composed of water and dissolved
substances).
The advantages of these techniques are still being studied
but we find the possibility of cultivating everywhere, even in geographic
regions where the climate is unfavorable to crops, where the land is not
workable or in countries with a small area that can be used for cultivation. In
fact, this type of agriculture also allows vertical indoor cultivation, a
method that saves precious space and optimizes water transport systems.
Finally, another great advantage concerns the control of
chemical-biological parameters, such as that of pH, the supply of nutrients,
the demand for oxygen, the absence of parasites and weeds.
From the point of view of pollution, although hydroponics
requires the use of electricity to thermostat the heat supplied to plants and
specific equipment for buildings, the absence of pesticides or herbicides sees
hydroponics, for the same product obtained, clearly ahead of the traditional.
Other types of alternative crops
Over time, techniques parallel to hydroponics have also
developed, including aquaponics and aeroponics.
In particular , aquaponics is a type of cultivation that
combines the growth of plant species with fish farming . Waste liquids from
fish tanks are used to irrigate crops. The plants feed on the harmful waste
substances and return clean water to the tank creating a healthy environment
for the fish. With this method of cultivation , 90% less water is used and the
plants grow directly above the tanks by sinking their roots in the filter that
cleans the water for the fish .
The growth takes place in times from 30 to 50% shorter than
a traditional crop thanks to the constant fertilization of the roots given by
the flow of waste water. One of the strengths of this type of cultivation is
that it reuses the water, recycles it and minimizes waste, allowing significant
economic savings.
Aeroponics, on the other hand, is a purely vertical type of
cultivation in which the plants completely do without a substrate, special net
pots are used in which the plants are placed with their roots in the open,
subsequently they are supplied by nebulization of water and nutrients. ,
everything is implemented thanks to turbines that guarantee controlled air
recirculation. On the one hand, the closed and isolated environment compared to
the outside will make the cultivated plants much less subject to aggression by
fungi and diseases, on the other hand, the roots will have a high level of
oxygenation and will thus be able to grow quickly with a large quantity minimum
of water and mineral salts.
The underwater vegetable garden of Noli Ligure
In the field of alternative agriculture there is also an
all-Italian association, Nemo's Garden , which has brought alternative
cultivation to combine all the techniques described above, facing a new
challenge, underwater cultivation. In 2012 the engineer Sergio Gamberini,
following some difficulties encountered in conventional basil farming in
Liguria, decided to design an underwater vegetable garden. What was born as an
imaginative test, however, gave excellent results in the short term , so much
so that many countries became interested in the project and thanks to EXPO
Milano 2015 it obtained important awards and funding from leading companies in
the agricultural sector.
The idea was simple, to create domes not far from the
Ligurian coasts in which to grow basil, a typical regional product. The first
biosphere of methacrylate of 2 meters in diameter, positioned between 6 and 10
meters deep, was put into operation in 2013 and the results in a few months
were extraordinary, the basil had sprouted after about thirty days from sowing
and the plants they developed quickly, yielding 300 grams of harvest in total.
To date there are 6 biospheres in which 65 to 95 plants each
find accommodation, on shelves positioned inside, the structures are anchored
to the seabed thanks to 28 chains to prevent movement caused by sea currents.
"They are 2 thousand liters of air that give an upward thrust equal to
about 2 tons "he explains" for this we need a solid anchoring system,
also to withstand currents and storm surges, and for this reason at the moment
we prefer to stay on 2 meters of diameter because a larger size would imply a
much stronger anchoring system ".
The operating principle is as follows: the sunlight filters
through the sea and the methacrylate of the biospheres (a winning material for
resistance and light transmission capacity, equal to almost 94%), heating the
air inside them and creating a difference. temperature, optimal for the plants
and to allow the water inside the biosphere to evaporate, leaving the sea salts
in the underlying layer .
The evaporated water subsequently condenses into fresh water
droplets on the walls of the biosphere, is collected by special condensers
which transport it to a channel in which a fertilizer is added, transported
from the surface, and finally come to nourish the plants. The
evaporation-condensation of water is monitored in terms of percentage of
Relative Humidity (RH%) inside the biosphere. Plants usually need 70-75% RH
under standard growing conditions. A nice advantage concerns precisely this
percentage which in the biosphere is very high: we are talking about values up
to 97% during the night and 85% during the day.
The air temperature inside the biosphere also shows an
optimal minimum variation of about 3-4 ° C between day and night. In the same
period (end of July) peaks of 30-31 ° C were recorded. The temperature inside
the biosphere is higher than that of sea water. This is why the evaporation of
seawater within each biosphere is so efficient.
The system is therefore in equilibrium and is
self-sufficient, it does not require additional energy other than that to keep
the temperatures inside the biosphere constant even at night, energy produced
by solar panels on the surface anchored to buoys.
Another interesting study is leading scientists to evaluate
the efficiency of fresh water production from this method.
If you are interest there is also a live streaming 24 hours
a day that allows anyone to follow the developments of this incredible project
" and we can interface with subjects who may have more knowledge in the
specific field: since we are not agronomists nor do we deal specifically of
this ".
And not only that, if you are interested it is also possible
to monitor the values inside the CO2, oxygen, pressure and humidity biospheres
directly from your screen through simple commands, the feeling is that of being
one of the scientists following the project.
The advantages
Since the first experiments, excellent advantages have been
noted compared to traditional cultivation, in a recent interview Gianni
Fontanesi of Ocean Reef, a company that deals with supporting underwater
cultivation with adequate equipment, declares: " after just 36-48 hours we
already notice germination, while the same type of plant, under normal
conditions, takes about 5-7 days. We are still trying to understand what
depends " , he says, " whether for stable humidity and temperature,
the presence of CO2 or for the higher pressure , or the relationship of all
these factors. We have no texts to consult on this, so we are still in the
study phase"In some cases there is a difference in the size of the leaves,
an increase in carotenoids and configurations of essential oils distributed in
different ways," the plant "explains" develops more pigments to
maintain chlorophyll photosynthesis even in low light. Regarding the flavor, we
didn't notice any significant differences . "
For now it is therefore clear that growth is faster in
biospheres, moreover the scent of basil is greater than in plants grown on the
surface, in fact from analyzes carried out there is a higher concentration of
essential oils and volatile molecules.
After basil, the association also experimented with the
cultivation of other aromatic and edible herbs, a couple of years ago plants
for pharmaceutical or cosmetic use, such as aloe, were also tested.
Unfortunately the company suffered a strong arrest in 2019
when, due to a storm, some biospheres were uprooted from the seabed causing
considerable damage to crops, however Nemo's Garden was not discouraged and
began to rebuild and implement its facilities while continuing the experiments.
The future prospects are innumerable and concern different sectors, from
tourism, with the idea of designing underwater observatories, to science, with
that of creating laboratories in which to carry out tests even of a different
nature, even up to space since the Space Agency Europeo expressed his interest.
In any case, this is a market still to be explored that will
surely bring great news in the near future in the field of alternative
agriculture.
