Environmental Engineering Reference
In-Depth Information
Further examples for
reasons why farmers chose speci
c crops for
their
wastewater irrigated
fields are listed in Hunshal et al. (
1997
). Some of these reasons
are linked to wastewater quality. Positive reasons besides high market demand
include good yields, ease of growth and resistance to pests and diseases. Reasons
against cultivating crops with wastewater include inferior quality of the produce,
vulnerability to pests and diseases and inhibited growth.
3.4 Farming Systems under Wastewater Irrigation
While information on crop types irrigated with wastewater is usually limited to
naming the crops, information on farming systems under wastewater irrigation is
almost non-existent. A possible reason for this is the fact that most research on
wastewater irrigation has been from a health and environmental risk perspective
with a much weaker focus on agricultural issues (cf. Carr et al.
2004a
; WHO
2006b
). Moreover, the variety of different farming systems under use in waste-
water-irrigated areas can suggest that there are few speci
c system requirements for
wastewater irrigation agriculture. Like any other agricultural system, the develop-
ment of a wastewater irrigated agricultural system depends on a wide range of
locally-specific technical, environmental, social and economic factors (cf. Moscoso
Cavallini and Egocheaga Young
2002
; Van der Hoek et al.
2002
; Bradford et al.
2003
; Ensink et al.
2004b
and Kurian et al.
2013
).
One obvious example for a factor speci
c to wastewater-irrigated agriculture is
issues related to nutrients. Due to the high content of nutrients, i.e. nitrogen,
potassium, phosphorus, zinc, boron and sulphur (WHO
2006b
), in wastewater,
farmers using this water for irrigation usually reduce or stop the use of mineral
fertilizers (Ensink et al.
2003
; Raschid-Sally and Jayakody
2008
). While this saves
them money, higher costs are often caused by increased incidences of pest attacks
and weeds that force farmers to use more labour and pesticides (Bradford et al.
2003
; Ensink et al.
2003
; Kurian et al.
2013
). In such cases, increased pesticide use
can then become a new source of health and environmental risks. If wastewater
irrigation is to make a real positive contribution to the health and environmental
situation, such sustainability issues of farming systems must be addressed.
Farm-based measures such as the use of alternative pesticides or integrated pest manage-
ment remain the key to risk reduction
Farming practices that reduce runoff, such as the
provision of vegetation cover or vegetation buffer strips, can significantly reduce the
probability of environmental impacts (Mateo-Sagasta et al.
2013
: 31).
…
Thus, in order to make wastewater irrigation sustainable, the agricultural focus
must not only be on crops but
—
—
more importantly
on agricultural systems. This is
'
also re
ected in a recent report by UNEP and IWMI calling for a shift from
water
for food
(Boelee
2011
). In order to
plan and design such systems systematically, it makes sense to approach wastewater
irrigation from the perspective of
'
to
'
water for multifunctional agroecosystems
'
'
an integrative discipline that includes elements
Search WWH ::
Custom Search