Agriculture Reference
In-Depth Information
Inputs
Outputs
Fertilisers
Pesticides
Energy
Heat
Light
Growing media
Water
Infrastructure
Carbon dioxide
Transport
Run off/leaching
Nutrients in water
Pes
cide residues
Waste
Crop
Packaging
Growing media
Carbon dioxide
G/H gasses
Light pollu
on
Greenhouses for intensive
plant production
Fig. 15.1
Schematic representation of the inputs and outputs that have the potential to have an
environmental impact from a greenhouse in northern Europe
Pesticides
Of all the resources and inputs used by the horticultural industry the use of pesti-
cides has been perceived as the greatest direct threat to both humans and the envi-
ronment. This concern dates back to the publication of
Silent Spring
(Carson
1962
)
which has been widely credited with launching the environmental movement and
making people more aware of their environment. However since then there has been
an increasing awareness of the impact of relatively small quantities of pesticides
can have on food chains and to the complex interactions in the environment.
Chemical pesticides are grouped as either generalists or specialists, providing
broad-spectrum or targeted control respectively. Environmental problems, particu-
larly loss of biodiversity, occur from the use of both groups. Generalists threaten
the population of non-target species including beneficial predators and parasitoids
or important pollinators, whilst specialists often contribute to a population build-up
of resistant target pests, and shorten the effective life-span of the chemical active
ingredient.
Greenhouses
Whilst horticultural production within greenhouses is highly economically efficient,
greenhouses pose particular environmental threats because they are the most inten-
sive users of resources. There are over 800,000 ha of greenhouses globally and can
be subdivided into two types; the 'northern' type, typically glasshouses with heating
and generally a high content of technology, and the 'southern' type, plastic-covered
houses with simple or no heating systems and a low level of technical complexity
(Bergstrand
2010
). The type of resources greenhouses use and the threats they pose
to the environment are represented diagrammatically in Fig.
15.1
.
