Agriculture Reference
In-Depth Information
Introduction
Horticultural production is primarily involved in the intensive use of resources, such
as land, water, labour and inputs such as fertilisers and pesticides. The use of such
resources in a concentrated space and time has the potential to negatively impact on
the local environment and worker welfare. In addition the transport of horticultural
produce over long distances, particularly by air transport, and reported in term of
food miles, is known to have a negative contribution to the global environment.
Environmental Threats
Land
Land occupied by the horticultural industry is limited and to sustain crop produc-
tivity it is essential that it is maintained as a fertile and productive resource. Inten-
sive agricultural and horticultural practices over the twentieth century, coupled with
growing greenhouse production, have dramatically impacted on the horticultural
landscape. Land and soil degradation caused by erosion (wind and water), organic
matter decline, compaction, salinization, reduced fertility and pollution all have the
potential of environmental mismanagement within horticulture. This in turn leads to
degradation and as a result impede on the biosecurity of future production.
Maintaining and improving fertility is critical to increasing yield; stagnant or
decreasing crop yields and per capita food production in Sub-Saharan Africa (SSA)
are primarily derived from lack of soil fertility (Henao and Baanante
2006
). Fertil-
ity, amongst other important soil characteristics, is affected by soil degradation, the
most common cause being erosion. It can occur in horticulture if large, open fields
are unprotected from wind erosion, or by flood irrigation carrying topsoil off fields
with little or no crop cover. Bridges and Van Baren (
1997
) state that the erosion of
1 cm ha
−1
of topsoil equates to a loss of between 100-150 t of soil. Every 100 t lost
carries with it 2000-2500 kg ha
−1
of humus, approximately 200 kg ha
−1
of nitrogen,
100 kg ha
−1
of phosphate and 500-1000 kg ha
−1
of potash. Poor soil quality for food
producers results in 10 million ha of cropland being abandoned annually due to soil
erosion (Pimentel
2006
). In addition the replenishment of the soil with lost nutrients
and organic matter is a lengthy and complicated process.
Water
Agriculture and horticulture combined is the largest user of freshwater, accounting
for 70 % of all bluewater withdrawals (Fischer et al.
2007
) worldwide and is mainly
used for irrigation. Climate change and population predictions warn of a global
