Agriculture Reference
In-Depth Information
Many people do not respect the seri-
ousness of environmental issues. Perhaps
such opinions are not based on solid data,
and as a consequence intensive production
systems such as greenhouse horticulture are
perceived as artificial processes which must
be considered as highly polluting. But quan-
titative environmental assessments do not
always agree with this point of view. For
instance, Muñoz
et al
. (2008) conducted an
LCA to compare the environmental impacts
of greenhouse tomato production with that
of open-field tomato production in the
Mediterranean region. They determined
that greenhouse production,
when properly
managed
, has a smaller environmental
impact than open field crops in most of the
evaluation categories. The great advantage
that could be gained by reducing the water
consumption in greenhouse systems located
in semi-arid regions, by Muñoz's compara-
tive study, was that the water consumption
to produce 1 kg of tomato was 24.2 l for
greenhouse production and 42.8 l for open
field production.
This is not meant to say the greenhouses
do not have any negative impact on the
environment. For instance, large areas filled
with greenhouses create a big visual impact,
a factor which is especially important in the
tourism areas of the Mediterranean coast.
Muñoz
et al
. (2008) observed that the green-
house structure itself had the greatest influ-
ence in the global warming category, due to
the energy and emissions during the pro-
duction of the steel and concrete structure.
Other LCA studies on unheated, natu-
rally ventilated greenhouses (Antón, 2004)
showed that the greenhouse structure and
auxiliary equipment (irrigation pipes, plas-
tics for mulching, crop supports, etc.)
accounted for 51% of the total gas emissions
of the whole production process (green-
house construction and operation). Within
the structure itself, the foundations and
perimeter walls made of concrete were
responsible for most of the emissions.
Currently efforts to redesign the foundation
system and to use recyclable concrete are in
progress to reduce the energy of construc-
tion. Antón's study also concluded that fer-
tilizer production and use is the main factor
that influences the environmental burden
associated with the increase of chemical
nutrients in water (eutrophication) and the
emission of sulfur and nitrogen compounds
that generate acid rain.
Good agricultural practices (GAP),
especially regarding irrigation and fertiliza-
tion programmes, are very important to
reduce emissions. However, waste manage-
ment by composting the plant biomass and
recycling of operational materials is another
obligation for future sustainable green-
houses. Recycling of waste has become very
important, as the reuse of plastic is contrib-
uting to increases in productivity and energy
efficiency. In the Almeria area of Spain,
practically all the greenhouse plastic cover
residues are recycled, as well as the crop
residues.
The lower energy inputs of simple cli-
mate control methods in Mediterranean
greenhouses, for example whitewashing to
provide shading as compared with mechan-
ical ventilation, contribute to reduce their
environmental impact (Antón
et al
., 2003).
Recent data, comparing the sustainability of
the greenhouse produce in Spain and The
Netherlands, show that primary fuel con-
sumption for cultivation and transport pur-
poses per kilogram of tomato, sweet pepper
and cucumber is estimated to be 13, 14-17
and 9 times greater, respectively, in The
Netherlands (Van der Velden
et al
., 2004).
Recent quantitative analysis has shown that
greenhouse production under passive low
technology greenhouses is not a highly pol-
luting process, provided that GAP are fol-
lowed, and significant input reductions are
achieved (Antón, 2004).
In some municipalities of the south of
Spain, motivated mainly for landscape rea-
sons or to avoid large concentrations of
greenhouses, regulations have been intro-
duced that restrict the development of
greenhouses.
Organic horticultural production involves
important restrictions in the use of fertiliz-
ers and pesticides that may have harmful
effects on the environment or can give rise
to the presence of residues in the horticul-
tural products. Organic production enjoys
an incipient and increasing demand in the
