Environmental Engineering Reference
In-Depth Information
Table 2 Selected agroecological practices relevant for wastewater irrigation
Practice
Short description
Relevance for wastewater reuse sys-
tems (examples)
Crop choice
Use of crop varieties that are resis-
tant to environmental stress and
diseases
Selecting plants that are ef cient in
converting wastewater into produce;
selecting plants that can take up high
quantities of contaminants
(hyperaccumulators*)
Spatial suc-
cession of
crops
In order to adapt to gradual changes
in environmental conditions, differ-
ent crops are grown in a spatial
sequence
Crops that can tolerate and absorb
contamination filter the water for
crops that are more sensitive
Organic
fertilization
Partial or total substitution of mineral
fertilizers by fertilizers based on
organic matter
Algal biomass from stabilization
ponds or other fast-growing plants as
slow-release fertilizer
Biological
pest control
Control of weeds, pests, and diseases
based on introduction of natural
enemies, pheromones or
Ecological and cheap way of dealing
with increased pest pressure resulting
from high nutrient levels in
wastewater
'
push
'
and
plants **
'
pull
'
Cover crops
Plants that do not compete with
crops used to cover the soil to reduce
weed growth, soil erosion and
increase soil fertility
Weed pressure on crops resulting
from the high nutrient availability in
wastewater irrigated areas can be
controlled; increased uptake of
nutrients from wastewater; reclama-
tion of soil quality
Intercropping
Cultivation of two or more crops on
the same field at the same time in
order to capture nutrients better and
use space more efficiently
Using space more ef ciently facili-
tates the uptake of a wider range and
quantity of nutrients from the
wastewater. This improves the treat-
ment effect and enhances nutrient
recycling rates
Agroforestry
Land-use systems involving trees
combined with crops and/or animals
on the same unit of land
Ef cient use of space with lines of
fast-growing tree species such as
eucalyptus; fruit on trees do not
come into direct contact with the
wastewater which lowers the risk of
food contamination; deep roots can
serve to prevent leeching of nutrients
into deeper soil layers and
groundwater
Habitat for bene cial animals that
feed on pest insects; potential for fast
biomass production
Source Nair ( 1991 ), Vandermeer ( 1995 ), Tanji and Kielen ( 2002 ), Cook et al. ( 2007 ), Dufumier
( 2010 ), Scheierling et al. ( 2010 ), Simmons et al. ( 2010 ), Altieri ( 2012 ), Wezel et al. ( 2013 )
* In a process called phytoremediation, speci c plants can be used to remove pollutants at minimal
cost:
Landscape
elements
Planting and management of vege-
tation strips and hedges in fields and
at field borders
The concentrations of metals accumulated in hyperaccumulator plants may be 100 times
greater than those occurring in non-accumulator plants growing on the same substrates ' (Simmons
et al. 2010 : 215)
** The push-pull strategy is a dual approach of integrated pest management: ' push ' plants between
the crops are used to make the protected crops unattractive to pests while ' pull ' plants lure them
away from the crops (Cook et al. 2007 )
'
Search WWH ::




Custom Search