Agriculture Reference
In-Depth Information
reduction in freshwater availability and an increase in demand (Falloon and Betts
2010 ). By 2030 there is an expected 40 % shortfall between supply and demand for
freshwater (Anon 2012a ). As the majority of horticultural crops are irrigated, the in-
dustry contributes to water scarcity problems and carries a responsibility to reduce
water use and causes of contamination.
Labour
An important feature of horticultural enterprises is their intensive use of labour.
Economic migration to concentrated areas of horticultural activity benefits com-
munities in terms of high employment rates but simultaneously increases demand
on natural resources and social infrastructure. Rapid population growth resulting
from expansion of the floriculture industry in Lake Naivasha, Kenya has caused un-
regulated urbanisation, decreased the quality of peri-urban land, overloaded sewage
systems and increased local pollution. Excessive extraction of water from the lake
for industrial and residential use has contributed in association with a drought to a
decline in water levels. In 2010 the lake receded to its lowest recorded level since
the 1940s (Harper et al. 2011 ). Over-exploitation of the water resource is contribut-
ing to reduced biodiversity, threatening future water security and local ecosystems
which are already endangered by the introduction of invasive species.
Fertilisers
Intensive crop production requires higher levels of inorganic fertilisers. As horticul-
tural crops are usually high value, the relative cost of these inputs to producers is
less important and as a result they may be applied in excess; consequently increas-
ing the risk of land and water pollution.
A central environmental impact on water quality and human health is excessive
nitrate levels. Nitrogen fertilisers which leach into the ground and runoff into water
courses contaminate surface water. Excessive nitrate (NO 3 ) in drinking water is as-
sociated with an illness of infants under 6 months' old called methemoglobinemia
or “blue-baby” syndrome (Knobeloch et al. 2000 ). However no cases have been
reported in the United Kingdom since 1972.
Another process is eutrophication which often takes place when contamination
from nitrate and phosphate fertilisers occurs in aquatic ecosystems, both fresh and
saltwater. The process derives from increased algal production accelerated by el-
evated nitrogen deposits (including nitrate and ammonia) within the water. This can
cause hypoxia- suffocation- of aquatic life beneath the water surface, disrupting bio
diverse ecosystems and promoting the development of nuisance algae (National
Research Council 2000 ).
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