Agriculture Reference
In-Depth Information
Northern greenhouses have a significantly higher rate of CO
2
emissions than
field grown crops or southern greenhouses. This is due to the combustion of natural
gas for heating and artificially raising CO
2
concentrations within the greenhouse.
Dutch greenhouse horticulture for example accounts for 79 % of all energy use in
Dutch agriculture (Lansink and Bezlepkin
2003
).
Unheated “southern” type greenhouses pose significant environmental threats.
Almería province in semi-arid southern Spain is Europe's largest provider of green-
house-grown fruit and vegetables with approximately 50,000 ha of greenhouses
under production. The horticultural industry in the region provides considerable
regional economic growth but production in this area has posed extensive local
environmental threats. Greenhouse horticulture on this scale has rapidly depleted
surface water and freshwater aquifers, subsequently replenished by seawater creat-
ing salinization of land and water. Intensive levels of biocide and fertiliser inputs
also have also added to the degradation of land and water quality, causing high
levels of eutrophication and reducing biodiversity in nearby aquatic ecosystems
(Wolosin
2006
).
Global Warming and Climate Change
The contribution made by horticulture to global warming and climate change is
through the processes of energy combustion, transportation, refrigerated storage
and inorganic inputs. The effects of the environmental impact of horticulture pro-
duction are entering a cyclical relationship with the impact on horticulture from
environmental change.
For instance the production methods for inorganic fertilisers are extremely en-
ergy intensive. The Harber-Bosch process used to create nitrogen fertiliser has in-
creased the quantity of nitrous oxide (N
2
0) within the nitrogen cycle, contributing
to global warming as its global warming potential is 298 carbon dioxide equivalent
(CO
2
e). It has been calculated that this production system, along with other in-
dustrial processes, has doubled the supply of reactive nitrogen within the global
environment.
Increased globalisation has led to greater travel and increased knowledge and
desire of exotic foods; consequently international trade in fresh horticultural
commodities and their subsequent consumption has increased. Transporting fresh
horticultural produce around the global by air has led to concern about the sustain-
ability of agricultural and food systems. Air freight accounts for 2.1 million t of
CO
2
e emissions in the UK - a mere 0.2 % of total UK CO
2
e emissions, but the rate
of growth accelerated between 1992 and 2002 when air freighted food produce
grew by 140 % (Watkiss
2005
). The CO
2
e is a measure of how much global warm-
ing a given type and amount of greenhouse gas may cause, using the functionally
equivalent amount or concentration of carbon dioxide (CO
2
) as the base reference.
This trend has been encouraged by a liberalising international and national regula-
