Al-Karaki, G.N. (2011, February). Utilization of treated sewage wastewater for green forage production in hydroponic system. Journal of Food & Agriculture (EJFA), 23(1), pg.15. Retrieved July 28, 2011 from EBSCOhost.
Introduction
Growing water scarcity threatens economic
development, sustainable human livelihoods,
environmental quality, and a host of other
societal goals in countries and regions around
the world. The water scarcity in Jordan for
example poses a serious challenge for all
sectors of water consumption (agriculture,
domestic, and industry); with the agricultural
sector being the most affected one that
consumes about 65% of the available water
(Malkawi, 2007). Jordan as well as many other
countries in the region is struggling to keep up
with the demand for fresh water (Malkawi,
2007; Al-Karaki and Al-Momani, 2010).
However, over-exploitation of water resources
(mainly ground water) has lead to deterioration
in the quantity and quality of irrigation water
and the booming population is jeopardizing
long-term water supplies. This would lead to
the reduction of irrigated areas and the change
towards cropping systems with lower water
demands or utilizing lower quality sources of
water (e.g., treated wastewater). The use of
wastewater in agriculture is increasing due to
water scarcity, population growth, and
urbanization, which all lead to the generation
of yet more wastewater in urban areas. By
2020, the volume of treated wastewater (WW)
in Jordan for example is expected to reach
about 230 million m³ (Al-Ghazawi et al.,
2007). Wastewater reuse in agriculture
represents a potentially important alternative
for fresh water and save it for drinking and
industry water supplies.
The use of WW in agriculture needs to be
done with precautions to avoid harming the
agricultural soils and to prevent any consumer
health risk. Therefore, use of treated
wastewater in agriculture in Jordan was largely
limited to irrigation of forages and forestry
(Nsheiwat, 2007).
The popular treatment process for sewage
in Jordan and some other countries in the
region is the use of stabilization pond to
separate sewage sludge from WW. The
secondary stage is an oxidation stage where
most of the organic matter is converted into
more stable forms by bacteria (Malkawi and
Mohammad, 2003). A tertiary treatment stage
is used to reduce the risks associated with the
use of secondary treated effluent mainly
bacteria and heavy metal concentrations.
Although the uptake of heavy metals by plants
might reduce the concentration of these
elements that might accumulate in the soil and
surface waters due to irrigation with WW,
Hook (1981) reported that good management
of the soil plant system is needed to minimize
pollution of ground water. However, extended
wastewater application in irrigation of crops
might result in accumulation of heavy metals in
soils and hence might cause soil deterioration
and ground water pollution (Malkawi and
Mohammad, 2003; Sidle et al., 1977; Xua etal.,
2010).
Recent studies have indicated that nutrients
from treated wastewater could be purified by
using some plant species in a hydroponic
system (Vaillant et al., 2004; Yang et al., 2008;
Snow and Ghaly, 2008; Rababah and Ashbolt,
2000; Rababah and al-Shuha, 2009). Moreover,
hydroponics (soilless) culture could lead to
solve the global issues such as the shortage of
water, environmental pollution, and instability
of ecological system in various ways.
Constituting high values for agricultural crops
by using low water inputs and high fertilizer
efficiencies is one of the methods used in
addressing the environmental and resource
problems (Sezen et al., 2010). Hydroponic
culture could be arranged with optimum
environmental medium for crop growth in
order to gain maximum yield and high quality
products.
Due to the rapidly growth population in
Jordan as well as many other countries in the
region, the demand for food and livestock
products increases, and this becomes a
challenge for the animal production sector to
meet this rapidly increased demand with the
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82
prevailing production conditions (e.g., water
shortage). The major constraints on livestock
production in Jordan and the other countries in
the arid and semiarid regions are the
inadequate quantities and poor quality of the
produced forages (e.g. green forage) in addition
to the high cost of imported feed (Al-Karaki,
2010; Ansar et al., 2010; Al-Hashimi, 2008).
Local production of forages in Jordan for
example covers only about 20% of its livestock
requirements (Harb and Awawdeh, 2008), and
this is mainly due to the limitation in water
resources that is needed for forage production.
These conditions force the Jordanian
government to import the rest of livestock
sector forage requirements from abroad, which
in turn led to the increased forage prices. In
2007 for example, forage prices in Jordan
increased by about 150% with increasing of
animal products prices as a consequence
(MOA, 2008). Therefore, Jordan needs to
increase its fodder production with good
quality, in large amounts, and in appropriate
cost to feed its grazing animals.
Achieving a suitable green fodder
production under the prevailing water-scarcity
conditions in Jordan and other countries in the
region, requires the introduction and
implementation of low quality water (treated
wastewater) and agricultural techniques which
minimize the water consumption and improve
yield per unit of water used. One of the
modern techniques that are considered
important for better water use efficiency as
well as for fodder production is hydroponic
culture. Hydroponic fodder production is a
well-known technique for high fodder yield,
year round production and least water
consumption (Tudor et al., 2003; Cuddeford,
1989; Al-Karaki, 2008). Al-Karaki (2010) has
reported that about 1.5-2 liters are needed to
produce 1 kg of green fodder hydroponically in
comparison to 73.5, 85.5, and 167 liters to
produce 1 kg of green fodder of forage barley,
alfalfa, and Rhodes grass under field conditions
in Sultanate of Oman. Fodder produced
hydroponically has a short growth period 7-10
days and requires only a small piece of land for
production to take place (Mooney, 2005;
Cuddeford, 1989). It has high feed quality, rich
with proteins, fibers, vitamins, and minerals
(Chung et al., 1989; Leontovich and Bobro,
2005; Al-Karaki and Al-Momani, 2010) with
therapeutic effects on animals (Kanauchi et al.,
1998; Boue et al., 2003). All these special
features of hydroponic culture, in addition to
others make it one of the most important
agricultural techniques currently in use for
green forage production in many countries
especially in arid and semi-arid regions.
The current study aimed at to investigate
green fodder yield, water use efficiency, and
quality and heavy metal contents of the
hydroponically produced barley fodder using
tertiary treated sewage wastewater for
irrigation and compare it with tap water
irrigation.
Materials and Methods
The research has been carried out during
2010 at the growth room of the Plant
Physiology Laboratory, Faculty of Agriculture,
Jordan University of Science and Technology,
Irbid, Jordan. A hydroponic system was
developed and manufactured at a local
workshop used in this study.
The hydroponic system
The hydroponic system is composed of two
cabinets (units) with metal frame and four
shelves each with a length of 200 cm, a width
of 55 cm, and a height of 240 cm. Each unit of
the system could carry 28 planting trays with
capacity to produce approximately 80-100 kg
green fodder per growth cycle (9 days),
depending on crop variety and growth
conditions (Al-Karaki and Al-Momani, 2010).
The horizontal area occupied by each unit of
the system was about 2 m2 including the
walkway between neighboring units. However,
the number of units of the hydroponic system
can be increased and planting date scheduled
for daily production of green fodder to meet the
daily demand of animals in the farm.
Polystyrene trays with a length of 45 cm, a
width of 25 cm and a depth of 8 cm were used
for growing seeds to produce green fodder.
These trays were obtained from the local
market. The units of hydroponic system have
Ghazi N. Al-Karaki
83
been arranged in the growth room close to
window to utilize natural illumination. An air
conditioning unit was used to control
temperature inside the growth room which was
maintained at 24±2ºC. The relative humidity in
the growth room ranged between 50 and 73%.
Plant material
Local barley cultivar was selected and used
in this study according to the results obtained
by Al-Karaki and Al-Momani (2010) that
indicated this cultivar out yielded the other
tested cultivars for green fodder production
under hydroponic conditions. Seeds of this
cultivar are composed from a mixture of
landraces and were obtained from the local
market of Irbid, Jordan. Seeds were subjected
to a germination test to check for their viability
before being used; the results showed that the
germination percentage was 95%.
Treatment of seeds and planting
Seeds of barley were cleaned from debris
and other foreign materials. Then the cleaned
seeds were surface sterilized by soaking for 30
minutes in a 20% sodium hypochlorite solution
(Clorox bleach) to prevent the formation of
mould. Planting trays and the growing cabinet
also were cleaned and disinfected. The seeds
were washed well from residues of bleach and
re-soaked in tap water overnight (about 12
hours) before sowing.
Seeds were sown in the polystyrene trays
lined with black plastic sheets and have holes
at the bottom to allow drainage of excess water
from irrigation. The seeding rate used in this
experiment was about 450 g/tray (equivalent to
about 4.0 kg/m2). The trays were stacked on the
shelves (7 trays per shelf in each hydroponic
unit).
Irrigation treatments
Trays were irrigated daily with three water
types: tertiary sewage treated wastewater
(WW), tap water (TW), and mixture of equal
amounts of WW and TW (WW mix). The
treated wastewater was obtained from the
Jordan University of Science and Technology
(JUST) treatment plant located inside the
campus (total area of JUST campus about 1100
ha). JUST plant is currently operating at about
600 m3 / day with a capacity of 2,500 m3 / day
(Al-Ghazawi et al., 2008).
Water use efficiency
Planting trays were irrigated twice a day
from each water type (early in the morning and
late in the afternoon) to provide enough water
to keep the seeds / seedlings moist. Daily
amounts of water used in irrigation were
recorded to compute the total amounts used in
irrigation throughout the experiment. Drained
water out of irrigation was collected in plastic
trays which were placed under each planting
tray were also recorded. The total water used
by plants (liters/tray) was computed as the
following:
Total water use (liters/tray) = Total
added water in irrigation- Total drained water
out of trays
Water use efficiency (WUE) was
computed according to:
WUE= tons green fodder produced/ m3
water used.
Fodder yield
At the end of experiment (9 days after
seeding), the produced green fodder was ready
for harvest, and green plants with their root
mats in the trays (Figure 1) were harvested and
the following data were recorded: total fresh
and dry fodder yields, seedling height, and
conversion factor (ratio of produced green
fodder to the initial planted seed weight).
Proximate chemical composition analysis
A representative fresh plant samples (about
150 grams) from every tray were taken at
harvest, oven-dried at 70°C for 48 hours,
weighed, and stored for chemical analysis. To
study the nutritional value of produced fodder,
proximate analysis for collected samples was
conducted and crude protein, crude fiber, crude
lipid, and dry matter contents were determined
according to the procedures of AOAC (2000).
Acid detergent fiber (ADF) was determined
using acetyl trimethyl ammonium bromide and
1N H2SO4 (Robertson and Van Soest, 1981).
Neutral detergent fiber (NDF) was determined
using sodium sulphite and sodium lauryl
sulphates (Van Soest et al., 1991).
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84
Mineral nutrient analysis
Representative fresh green fodder samples
(150 g) from each treatment were taken in four
replicates at harvest, oven-dried at 70°C for 48
hours, ground to pass a 0.5 mm sieve, and
stored for chemical analysis. The nitrogen
content was determined using Kjeldahl's
method. Samples for the determination of
mineral nutrients were prepared using dry
ashing method (Schouwenberg and Walinge,
1973). Phosphorus was determined using
spectrophotometer (Watanabe and Olsen
1965); potassium and sodium by flame
photometer (Ryan et al., 2001), Ca, Mg, Mn,
Zn and B by Atomic Absorption Spectrometer
(Varian AA 240 FS). Some nutritional
elements (N, P, K, Ca, Mg, Zn, Na, and B) for
various irrigation waters were also analyzed.
Heavy metals analysis
Dried and ground plant samples were
analyzed for heavy metals Cd, Ni, Pb, and Cr
were measured in the dry ash digestion for the
fodder dried samples by Graphite Tube
Atomizer (GTA 120). Chemical analyses for
various irrigation waters were also carried out
separately for heavy metals (Cd, Ni, Pb and
Cr).
Microbial quality analysis
Barley seedlings produced in this study and
irrigated with WW were analyzed for presence
of microbial pathogens (total faucal coliforms,
E. coli, and nematode eggs).
Experimental design and statistical analysis
The completely randomized design (CRD)
was used with four replicates. Data were
statistically analyzed using analysis of variance
(ANOVA) according to the statistical package
MSTAT-C (Michigan State Univ., East
Lansing, MI, USA). Probabilities of
significance among treatments and LSD (P≤
0.05) were used to compare means among
treatments.
Results and Discussion
Irrigation water quality
The analysis of irrigation water used for the
various treatments is reported in Table 1. The
salinity of irrigation water was 0.48 dS/m (tap
water) and 1.13 dS/m (WW). The pH values
were 7.84 for the tap water and 7.82 for the
WW. It has been reported that hydroponically
grown barley can tolerate salinity of water up
to 6 dS/m without any impact on seed
germination or crop yield (Bagci and Yilmaz,
2003).
Nitrogen, K, Na, Cl and Zn were present in
higher concentrations in WW compared to tap
water (Table 1). However, similar amounts of
P, Mg, and B were recorded in both WW and
TW. The concentrations of these elements are
considered lower than those recommended for
nutrient solutions in crop production (e.g.,
vegetables) under hydroponic systems
according to Benton (2005). Hydroponic green
fodder is usually grown with no or little added
fertilizers due to the short period of growth
(Al-Karaki and Al-Momani, 2010). However,
Al-Karaki and Al-Hashimi (2010)
recommended that no need to use fertilizer for
green barley fodder production under
hydroponic conditions, when they found that
chemical fertilization at 10% or 20% of
Hoagland's solution had no significant effects
on barley green fodder yield compared to no
fertilization (control).
Ghazi N. Al-Karaki
85
Table 1. The characteristics of treated wastewater and tap water used for irrigation in this study.
Parameter Tap water Treated wastewater
EC dS/m 0.48 1.13
pH 7.84 7.82
DO (mg/L) - 3.1
BOD5 (mg/L) - 10
COD (mg/L) - 25
NO3-N (mg/L) 10 30
Cl (mg/L) 23 134
PO4-P (mg/L) 5.44 5.53
Ca (ppm) 67.2 42.2
Mg (ppm) 16.6 16.1
K (ppm) 102 114
Na (ppm) 81.1 500
Zn (ppm) 0.013 0.025
B (ppm) 0.057 0.052
To know the potential risk of heavy metals
in irrigation water to plants and hence animals
and human beings, it is necessary to evaluate
their concentrations in WW. The heavy metal
concentrations of WW and TW used in this
study are presented in Table 2. Although the
nickel, cadmium, chromium, and lead contents
in WW are much higher than those in TW
irrigation waters, the levels of these elements in
WW are lower than the acceptable levels set
for irrigation water for crop production
according to FAO guidelines (FAO, 1992).
Table 2. Toxic elements content in water used for irrigation and the maximum concentrations of heavy
metals in treated wastewater allowed to be used for irrigation according to FAO (1992).
Metal Tap water
Treated
wastewater
Maximum
concentrations
_____________ ppm _______________
Chromium (Cr) 0.0039 0.0090 0.10
Cadmium (Cd) 0.0005 0.0032 0.01
Nickel (Ni) 0.0003 0.0063 0.20
Lead (Pb) 0.0041 0.0147 5.00
Microbial quality in produced fodder
Irrigation with wastewater can represent a
major threat to public health (of both humans
and livestock), food safety and environmental
quality. The microbial quality of wastewater is
usually measured by the concentration of the
two primary sources of water-borne-fecal
coliforms and nematode eggs (Ayers et al.,
1992). Presence of E. coli in irrigation waters
is used as indicator of fecal pollution as this
organism can pose a significant health risks
(Dufour, 1997). Results of analysis of produced
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86
barley fodder seedlings showed no presence of
any pathogenic microorganisms (Table 3).
However, in a study conducted by Al-Ghazawi
et al. (2008) using the same source of WW for
production of barley under field conditions,
they found no or low populations of some
pathogenic organisms in barley seedlings
grown in soil under field conditions (Table 3).
Table 3. Analysis of pathogenic microorganism counts in hydroponic and field grown barley irrigated
with treated sewage wastewater.
Parameter Counts
Barley grown
hydroponically
Barley grown in field
(Al-Ghazawi et al. 2008)
Total coliforms
Not found
4.3 MPN/g
E. coli
Not found
< 0.3 MPN/g
Helminthes eggs
Not found
Not found
Fodder yield
Significant differences among various
water treatments used in this study were found
in green and dry biomass traits (Table 1).
Higher yields of fresh green and dry matter
were recorded in plants irrigated with WW
than for TW (Figure 1 and 2). Table 4 shows
barley fodder yields (on fresh green and dry
weight basis) and plant heights at harvest.
Average green forage yield ranged from 224
tones/ha with tap water to around 320 tones/ha
with WW for one production cycle (9 days).
A total possible green fodder yield of 5600 and
8000 tons/ha/year can be achieved with the
hydroponic system (with 25 harvests per year)
using TW and WW in irrigation, respectively.
This is more than 66 and 94 times for TW and
WW, respectively, greater than the green
fodder yield obtained from conventional field
grown forage of 85 tons/ha/year. Ghaly et al.
(2007) reported that forage wheat grown
hydroponically has exceeded some
conventional forage crops (e.g. alfalfa) by 98
folds under irrigation with wastewater.
Table 4. Green fodder (fresh and dry) yield, plant height, and ratio of produced green fodder / initial
planted seed weight of barley fodder produced under hydroponic conditions and irrigated with treated
wastewater and tap water.
Water
Type
Fresh fodder
yield
Dry fodder
yield
Seedling
height
Ratio of produced
fodder / planted
seed weight
ton/ ha ton/ ha cm
TW 224 c* 37.9 c 18.7 c 4.74 b
WW mix 276 b 45.2 b 20.3 b 5.02 b
WW 320 a 54.4 a 22.7 a 6.00 a
* Means followed by the same letter(s) in each column are not significantly different
at 5% probability level.
Ghazi N. Al-Karaki
87
Figure 1. Green fodder ready for harvest (A) and harvested green barley fodder
with their root mats (B).
Figure 2. Green fodder biomass produced under irrigation with WW (A) was
higher than that irrigated with TW (B).
Results of this study showed that green
fodder produced with WW was higher by 40%
than that with TW. Similar trend has been
noticed for dry matter production (Table 4).
Al-Ajmi et al. (2009) found that total barley
fodder yield increased by 1.5 times when
irrigated with treated sewage water over yield
using tap water. Green forage production has
been reported to highly correlate to N content
of irrigation water (Azevedo et al., 2006),
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88
which conformed to the results of analysis of
water used in this study that indicated that WW
contains higher N than tap water.
The heights of barley seedlings obtained in
this study were significantly higher when
irrigated with WW than irrigation with other
types of water. The average barley seedling
height ranged between 18.7 cm (TW) and 22.7
cm (WW) at harvest. Similar values of plant
heights were reported by Al-Hashmi (2008)
who obtained barley plants of height 20-22cm
grown hydroponically and irrigated with tap
water. Barley green fodder produced in this
study was 4.74 to 6 times more than the initial
weight of sown seeds (Table 4). These values
are comparable with the ones reported by
Sneath and Mclntosh (2003). Al-Hashimi
(2008) obtained slightly lower ratios of barley
produced fodder to planted seeds weight using
tap water in irrigation. However, Al-Karaki
(2008) reported that this ratio reached up to 8
times in barley green fodder produced
hydroponically.
Water use efficiency
Hydroponically produced fodder was found
to enhance the efficiency of water use (WUE).
Brandley and Marulanda (2000) reported that
hydroponic green fodder production technique
requires only about 10-20% of the water
needed to produce the same amount of crop in
soil culture. While Al-Karaki (2010) reported
that only 3-5% of water is needed to produce
the same amount of fodder in comparison to
that produced under field conditions. In this
study, barley plants had utilized 25% more
water when irrigated with TW than with WW,
while dry matter production with WW was
higher than TW by about 28% (Table 5). This
improvement in crop yield might be
appreciable and economically feasible.
Irrigation with WW was found to use water
more efficiently in producing green fodder than
irrigation with the other two types of water
(TW and WW mix) when used only 1.26 m3
water to produce 1 ton of hydroponic green
fodder in comparison to 1.38 and 1.56 m3 water
in WW mix and TW, respectively (Table 5).
Similar data were revealed by other researchers
(Al-Hashmi, 2008; Al-Karaki and Al-Momani,
2010).
Table 5. Total water use and water use efficiency of barley fodder produced under hydroponic
conditions and irrigated with different water types.
Water type Water use Water use efficiency
m3 / ton fresh matter
ton fresh matter / m3
ton dry matter / m3
TW 1.56 a* 0.641 b 0.108 b
WW mix 1.38 b 0.725 a 0.119 b
WW 1.26 b 0.794 a 0.136 a
* Means followed by the same letter(s) in each column are not significantly different
at 5% probability level.
Producing green fodders under hydroponic
conditions is a highly efficient process in term
of water saving when compared to field
production of green fodders as the production
of 1 kg of barley green fodder under field
conditions needs 73.5-167 liters of water (Al-
Karaki, 2010). Al-Karaki and Al-Momani
(2010) reported that only 14 kg fresh matter/m3
water were obtained for field irrigated barley,
compared to about 680 kg fresh matter/m3
water obtained in this study. This is a
tremendous improvement in WUE and
Ghazi N. Al-Karaki
89
indicated that hydroponic system could play a
significant role in improving water use
efficiency in Jordan and other countries in the
region with shortage in irrigation water.
Fodder quality
The proximate analysis for the produced
dry fodder showed higher contents of crude
protein, neutral (NDF) and acid detergent fiber
(ADF) in WW in comparison with barley
fodder irrigated with other types of water
(Table 6). The protein content in
hydroponically produced fodder reached about
27.4% irrigated with WW, while the values of
barley fodder irrigated with WW mix and TW
were 24.9% and 25.2%, respectively (Table 6).
However, no significant differences were
determined between crude fiber and crude fat
content in the fodder irrigated with three types
of water (Table 6). The values of ADF and
NDF in dry fodder ranged between 11-13.4%
for ADF and between 28.8-32.7% for NDF
(Table 6). Owens (2009) reported that the
lower values of ADF (<30%) and NDF (<40%)
in the fodder are considered of good nutritional
values. The findings related to produce green
fodder in this study indicated that irrigation
with WW or WW mix may have no adverse
effect on health or performance of grazing
animals. It offers good use of treated
wastewater to increase farmers' benefits.
Proximate chemical analyses indicated that
barely fodder may probably be superior in
some aspects to field grown alfalfa hay used
mainly as a source of roughage for livestock in
Jordan and the countries of region. Al-Karaki
and Al-Momani (2010) reported that
hydroponic barley fodder has higher crude
protein values and less fiber content than field
grown alfalfa forages. Dry matter content in
the produced fodder in this study ranged
between 16.4% and 17.1%, and these values
are not significantly different between different
barley fodders irrigated with different water
types (Table 6). The nutrient requirements of
the seedlings are quite or partially satisfied
from the reserved compounds in the seeds
(Bewley, 1997).
Table 6. Proximate analyses of barley irrigated with treated wastewater (WW), tap water (TW) or
mixture of WW and TW under hydroponic conditions (dry matter basis).
Water type
Crude
protein Crude fat
Crude
fiber
Acid
detergent
fiber
Neutral
detergent
fiber
Dry
matter
content
____________________ % __________________
Tap water 25.2 b* 5.2 a 14.3 a 11.7 b 28.8 b 16.4 a
WW mix 24.9 b 5.4 a 15.5 a 13.4 a 32.7 a 16.9 a
WW 27.4 a 4.8 a 15.6 a 13.1 a 31.2 ab 17.1 a
* Means followed by the same letter(s) in each column are not significantly different at 5% probability level.
Nutrient mineral content in barley fodder
Minerals have a major nutritional
significance for livestock and feed deficiencies
in elements, such as Ca, Fe, Mn, Zn, can lead
to a variety of health problems from anemia to
osteoporosis (Liu et al., 2007). Concentration
of nutrient elements analyzed in dry barley
fodder is presented in Table 7. Except for N,
Mg, and Na, there were no significant
differences in concentrations of the analyzed
elements (P, K, Ca, Zn, and Mn) between those
irrigated with WW and with tap water or WW
mix. The short growing period of barley
fodder under hydroponic conditions and its
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90
dependency on its own reserved compounds for
the early growing stages may be attributed to
the low variations of mineral nutrients in the
produced fodder irrigated with WW and tap
water. The nutrient requirements of the
seedlings after germination are quite low and
partially satisfied from the reserved compounds
in the seeds (Bewley, 1997).
Table 7. The concentration of mineral nutrients in barley green fodder produced under hydroponic
conditions and irrigated with different water types (dry matter basis).
Water
type N P K Mg Ca Na Zn
Mn
_____________________(mg/g) _________________ _____(mg/kg) ____
TW 40.3 b* 6.05 a 8.63 a 3.78 b 3.19 a 2.50 c 5.58 a 9.5 a
WW mix 39.8 b 5.65 a 9.39 a 4.05 a 2.94 a 2.84 b 6.14 a 11.7 a
WW 43.8 a 5.52 a 9.26 a 4.12 a 2.68 a 3.10 a 5.36 a 12.1 a
* Means followed by the same letter(s) in each column are not significantly different at 5% probability level.
The high concentrations of N and Mg in
dry fodder irrigated with WW might be due to
their high concentrations in the WW used for
irrigation. This might indicate that the WW is
a good source of these minerals that can be
used for irrigation under hydroponic
conditions. Na levels increased significantly in
barley fodder irrigated with WW or WW mix.
This is may be a result of their high
concentrations in WW used for irrigation. Al-
Ajmi et al. (2009) reported that except for Ca,
no significant differences were found between
the fodder irrigated with treated wastewater
and tap water for the nutrient elements N, P, K,
Ca, and Fe contents. Compared to the long
term effect of WW irrigation, Rusan et al.
(2007) reported that N, P, K, Cu, Zn, Fe, and
Mn increased significantly in soils as years of
WW irrigation increased in the same lands.
Generally, the results of this study indicated
that the contents of those essential minerals
were available in the produced green fodder
around their usual level, thus, WW can be used
for irrigation under hydroponic conditions
without any adverse effects regarding to these
elements.
Heavy metal content in fodder
Application of WW in irrigation crops
usually contain elevated levels of heavy metals
(specifically Cd, Ni and Pb) which might
accumulate in fodder and cause toxic effects on
human by affecting animal products due to
direct intake of contaminated fodder (Adriano,
2001). Cadmium concentration in barley
fodder was higher in WW than TW or WW
mix irrigated plants (Table 8). Cadmium levels
found in barley fodder ranged between 0.020
ppm (in tap water) and 0.032 ppm (in WW).
These are below the limits set by WHO and
FAO which are 0.2 mg/kg fresh weight for
leafy vegetables and fresh herbs (WHO/FAO,
2007).
The low accumulation of Cd in barley
tissues may be attributed to the slightly basic
nature of the WW water. Nickel concentrations
in barley fodder ranged between 0.057 ppm
(tap water) and 0.47 ppm (WW) (Table 8).
These are below the limits by FAO for edible
crops (FAO, 1992). However, Ni is considered
an essential element for small grains (e.g.,
barley).
Lead (Pb) level in dry fodder was higher in
those plants irrigated with WW, ranging
between 0.433 ppm (tap water) and 0.903 ppm
(WW) on dry matter basis. These levels are
lower than those reported by Kabata-Pendias
(2000) and Finister et al. (2004) for edible
crops. No significant differences were noted
for Cr in dry fodder regardless of water type
used in irrigation (Table 8).
Ghazi N. Al-Karaki
91
Table 8. The concentration of heavy metals (ppm) in green barley fodder produced under hydroponic
conditions and irrigated with different water types.
Pb Ni Cr Cd
Water type _____________ ppm _________________
TW 0.433 c* 0.057 c 0.11 a 0.020 c
WW mix 0.647 b 0.240 b 0.09 a 0.028 b
WW 0.903 a 0.47 b 0.08 a 0.032 ab
Safe limits in plants
(vegetative parts) 5.0† 1.5‡ 20‡ 0.2†
* Means followed by the same letter(s) in each column are not significantly different
at 5% probability level.
† according to WHO/FAO (2007)
‡ according to Awashthi (2000)
Conclusions
Hydroponic system is a potential technique
for barley fodder production with less water
consumption where water is the main limiting
factor for agricultural production (e.g., Jordan).
Tertiary treated sewage wastewater is a feasible
source for irrigation of hydroponically
produced barley fodder. The current study
shows the superiority of WW irrigated fodder
barley over that irrigated with tap water in
several aspects related to production and
quality of the produced barley crop. This
indicated that WW is a good source of nutrients
needed for plant growth to promote high yields.
The accumulation of heavy metals in the
fodder irrigated with WW was apparent, yet
below FAO accepted limits. The use of WW in
hydroponic systems may reduce the risk of
heavy metal accumulation in the soil with
prolonged use. It is also considered an
environmentally sound waste water disposal
practice compared to direct disposal into
surface or ground water bodies.
Acknowledgments
The author is grateful to the Deanship of
Scientific Research at Jordan University of
Science and Technology (Jordan) for funding
this research.
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Introduction
Growing water scarcity threatens economic
development, sustainable human livelihoods,
environmental quality, and a host of other
societal goals in countries and regions around
the world. The water scarcity in Jordan for
example poses a serious challenge for all
sectors of water consumption (agriculture,
domestic, and industry); with the agricultural
sector being the most affected one that
consumes about 65% of the available water
(Malkawi, 2007). Jordan as well as many other
countries in the region is struggling to keep up
with the demand for fresh water (Malkawi,
2007; Al-Karaki and Al-Momani, 2010).
However, over-exploitation of water resources
(mainly ground water) has lead to deterioration
in the quantity and quality of irrigation water
and the booming population is jeopardizing
long-term water supplies. This would lead to
the reduction of irrigated areas and the change
towards cropping systems with lower water
demands or utilizing lower quality sources of
water (e.g., treated wastewater). The use of
wastewater in agriculture is increasing due to
water scarcity, population growth, and
urbanization, which all lead to the generation
of yet more wastewater in urban areas. By
2020, the volume of treated wastewater (WW)
in Jordan for example is expected to reach
about 230 million m³ (Al-Ghazawi et al.,
2007). Wastewater reuse in agriculture
represents a potentially important alternative
for fresh water and save it for drinking and
industry water supplies.
The use of WW in agriculture needs to be
done with precautions to avoid harming the
agricultural soils and to prevent any consumer
health risk. Therefore, use of treated
wastewater in agriculture in Jordan was largely
limited to irrigation of forages and forestry
(Nsheiwat, 2007).
The popular treatment process for sewage
in Jordan and some other countries in the
region is the use of stabilization pond to
separate sewage sludge from WW. The
secondary stage is an oxidation stage where
most of the organic matter is converted into
more stable forms by bacteria (Malkawi and
Mohammad, 2003). A tertiary treatment stage
is used to reduce the risks associated with the
use of secondary treated effluent mainly
bacteria and heavy metal concentrations.
Although the uptake of heavy metals by plants
might reduce the concentration of these
elements that might accumulate in the soil and
surface waters due to irrigation with WW,
Hook (1981) reported that good management
of the soil plant system is needed to minimize
pollution of ground water. However, extended
wastewater application in irrigation of crops
might result in accumulation of heavy metals in
soils and hence might cause soil deterioration
and ground water pollution (Malkawi and
Mohammad, 2003; Sidle et al., 1977; Xua etal.,
2010).
Recent studies have indicated that nutrients
from treated wastewater could be purified by
using some plant species in a hydroponic
system (Vaillant et al., 2004; Yang et al., 2008;
Snow and Ghaly, 2008; Rababah and Ashbolt,
2000; Rababah and al-Shuha, 2009). Moreover,
hydroponics (soilless) culture could lead to
solve the global issues such as the shortage of
water, environmental pollution, and instability
of ecological system in various ways.
Constituting high values for agricultural crops
by using low water inputs and high fertilizer
efficiencies is one of the methods used in
addressing the environmental and resource
problems (Sezen et al., 2010). Hydroponic
culture could be arranged with optimum
environmental medium for crop growth in
order to gain maximum yield and high quality
products.
Due to the rapidly growth population in
Jordan as well as many other countries in the
region, the demand for food and livestock
products increases, and this becomes a
challenge for the animal production sector to
meet this rapidly increased demand with the
Emir. J. Food Agric. 2011. 23 (1): 80-94
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82
prevailing production conditions (e.g., water
shortage). The major constraints on livestock
production in Jordan and the other countries in
the arid and semiarid regions are the
inadequate quantities and poor quality of the
produced forages (e.g. green forage) in addition
to the high cost of imported feed (Al-Karaki,
2010; Ansar et al., 2010; Al-Hashimi, 2008).
Local production of forages in Jordan for
example covers only about 20% of its livestock
requirements (Harb and Awawdeh, 2008), and
this is mainly due to the limitation in water
resources that is needed for forage production.
These conditions force the Jordanian
government to import the rest of livestock
sector forage requirements from abroad, which
in turn led to the increased forage prices. In
2007 for example, forage prices in Jordan
increased by about 150% with increasing of
animal products prices as a consequence
(MOA, 2008). Therefore, Jordan needs to
increase its fodder production with good
quality, in large amounts, and in appropriate
cost to feed its grazing animals.
Achieving a suitable green fodder
production under the prevailing water-scarcity
conditions in Jordan and other countries in the
region, requires the introduction and
implementation of low quality water (treated
wastewater) and agricultural techniques which
minimize the water consumption and improve
yield per unit of water used. One of the
modern techniques that are considered
important for better water use efficiency as
well as for fodder production is hydroponic
culture. Hydroponic fodder production is a
well-known technique for high fodder yield,
year round production and least water
consumption (Tudor et al., 2003; Cuddeford,
1989; Al-Karaki, 2008). Al-Karaki (2010) has
reported that about 1.5-2 liters are needed to
produce 1 kg of green fodder hydroponically in
comparison to 73.5, 85.5, and 167 liters to
produce 1 kg of green fodder of forage barley,
alfalfa, and Rhodes grass under field conditions
in Sultanate of Oman. Fodder produced
hydroponically has a short growth period 7-10
days and requires only a small piece of land for
production to take place (Mooney, 2005;
Cuddeford, 1989). It has high feed quality, rich
with proteins, fibers, vitamins, and minerals
(Chung et al., 1989; Leontovich and Bobro,
2005; Al-Karaki and Al-Momani, 2010) with
therapeutic effects on animals (Kanauchi et al.,
1998; Boue et al., 2003). All these special
features of hydroponic culture, in addition to
others make it one of the most important
agricultural techniques currently in use for
green forage production in many countries
especially in arid and semi-arid regions.
The current study aimed at to investigate
green fodder yield, water use efficiency, and
quality and heavy metal contents of the
hydroponically produced barley fodder using
tertiary treated sewage wastewater for
irrigation and compare it with tap water
irrigation.
Materials and Methods
The research has been carried out during
2010 at the growth room of the Plant
Physiology Laboratory, Faculty of Agriculture,
Jordan University of Science and Technology,
Irbid, Jordan. A hydroponic system was
developed and manufactured at a local
workshop used in this study.
The hydroponic system
The hydroponic system is composed of two
cabinets (units) with metal frame and four
shelves each with a length of 200 cm, a width
of 55 cm, and a height of 240 cm. Each unit of
the system could carry 28 planting trays with
capacity to produce approximately 80-100 kg
green fodder per growth cycle (9 days),
depending on crop variety and growth
conditions (Al-Karaki and Al-Momani, 2010).
The horizontal area occupied by each unit of
the system was about 2 m2 including the
walkway between neighboring units. However,
the number of units of the hydroponic system
can be increased and planting date scheduled
for daily production of green fodder to meet the
daily demand of animals in the farm.
Polystyrene trays with a length of 45 cm, a
width of 25 cm and a depth of 8 cm were used
for growing seeds to produce green fodder.
These trays were obtained from the local
market. The units of hydroponic system have
Ghazi N. Al-Karaki
83
been arranged in the growth room close to
window to utilize natural illumination. An air
conditioning unit was used to control
temperature inside the growth room which was
maintained at 24±2ºC. The relative humidity in
the growth room ranged between 50 and 73%.
Plant material
Local barley cultivar was selected and used
in this study according to the results obtained
by Al-Karaki and Al-Momani (2010) that
indicated this cultivar out yielded the other
tested cultivars for green fodder production
under hydroponic conditions. Seeds of this
cultivar are composed from a mixture of
landraces and were obtained from the local
market of Irbid, Jordan. Seeds were subjected
to a germination test to check for their viability
before being used; the results showed that the
germination percentage was 95%.
Treatment of seeds and planting
Seeds of barley were cleaned from debris
and other foreign materials. Then the cleaned
seeds were surface sterilized by soaking for 30
minutes in a 20% sodium hypochlorite solution
(Clorox bleach) to prevent the formation of
mould. Planting trays and the growing cabinet
also were cleaned and disinfected. The seeds
were washed well from residues of bleach and
re-soaked in tap water overnight (about 12
hours) before sowing.
Seeds were sown in the polystyrene trays
lined with black plastic sheets and have holes
at the bottom to allow drainage of excess water
from irrigation. The seeding rate used in this
experiment was about 450 g/tray (equivalent to
about 4.0 kg/m2). The trays were stacked on the
shelves (7 trays per shelf in each hydroponic
unit).
Irrigation treatments
Trays were irrigated daily with three water
types: tertiary sewage treated wastewater
(WW), tap water (TW), and mixture of equal
amounts of WW and TW (WW mix). The
treated wastewater was obtained from the
Jordan University of Science and Technology
(JUST) treatment plant located inside the
campus (total area of JUST campus about 1100
ha). JUST plant is currently operating at about
600 m3 / day with a capacity of 2,500 m3 / day
(Al-Ghazawi et al., 2008).
Water use efficiency
Planting trays were irrigated twice a day
from each water type (early in the morning and
late in the afternoon) to provide enough water
to keep the seeds / seedlings moist. Daily
amounts of water used in irrigation were
recorded to compute the total amounts used in
irrigation throughout the experiment. Drained
water out of irrigation was collected in plastic
trays which were placed under each planting
tray were also recorded. The total water used
by plants (liters/tray) was computed as the
following:
Total water use (liters/tray) = Total
added water in irrigation- Total drained water
out of trays
Water use efficiency (WUE) was
computed according to:
WUE= tons green fodder produced/ m3
water used.
Fodder yield
At the end of experiment (9 days after
seeding), the produced green fodder was ready
for harvest, and green plants with their root
mats in the trays (Figure 1) were harvested and
the following data were recorded: total fresh
and dry fodder yields, seedling height, and
conversion factor (ratio of produced green
fodder to the initial planted seed weight).
Proximate chemical composition analysis
A representative fresh plant samples (about
150 grams) from every tray were taken at
harvest, oven-dried at 70°C for 48 hours,
weighed, and stored for chemical analysis. To
study the nutritional value of produced fodder,
proximate analysis for collected samples was
conducted and crude protein, crude fiber, crude
lipid, and dry matter contents were determined
according to the procedures of AOAC (2000).
Acid detergent fiber (ADF) was determined
using acetyl trimethyl ammonium bromide and
1N H2SO4 (Robertson and Van Soest, 1981).
Neutral detergent fiber (NDF) was determined
using sodium sulphite and sodium lauryl
sulphates (Van Soest et al., 1991).
Emir. J. Food Agric. 2011. 23 (1): 80-94
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Mineral nutrient analysis
Representative fresh green fodder samples
(150 g) from each treatment were taken in four
replicates at harvest, oven-dried at 70°C for 48
hours, ground to pass a 0.5 mm sieve, and
stored for chemical analysis. The nitrogen
content was determined using Kjeldahl's
method. Samples for the determination of
mineral nutrients were prepared using dry
ashing method (Schouwenberg and Walinge,
1973). Phosphorus was determined using
spectrophotometer (Watanabe and Olsen
1965); potassium and sodium by flame
photometer (Ryan et al., 2001), Ca, Mg, Mn,
Zn and B by Atomic Absorption Spectrometer
(Varian AA 240 FS). Some nutritional
elements (N, P, K, Ca, Mg, Zn, Na, and B) for
various irrigation waters were also analyzed.
Heavy metals analysis
Dried and ground plant samples were
analyzed for heavy metals Cd, Ni, Pb, and Cr
were measured in the dry ash digestion for the
fodder dried samples by Graphite Tube
Atomizer (GTA 120). Chemical analyses for
various irrigation waters were also carried out
separately for heavy metals (Cd, Ni, Pb and
Cr).
Microbial quality analysis
Barley seedlings produced in this study and
irrigated with WW were analyzed for presence
of microbial pathogens (total faucal coliforms,
E. coli, and nematode eggs).
Experimental design and statistical analysis
The completely randomized design (CRD)
was used with four replicates. Data were
statistically analyzed using analysis of variance
(ANOVA) according to the statistical package
MSTAT-C (Michigan State Univ., East
Lansing, MI, USA). Probabilities of
significance among treatments and LSD (P≤
0.05) were used to compare means among
treatments.
Results and Discussion
Irrigation water quality
The analysis of irrigation water used for the
various treatments is reported in Table 1. The
salinity of irrigation water was 0.48 dS/m (tap
water) and 1.13 dS/m (WW). The pH values
were 7.84 for the tap water and 7.82 for the
WW. It has been reported that hydroponically
grown barley can tolerate salinity of water up
to 6 dS/m without any impact on seed
germination or crop yield (Bagci and Yilmaz,
2003).
Nitrogen, K, Na, Cl and Zn were present in
higher concentrations in WW compared to tap
water (Table 1). However, similar amounts of
P, Mg, and B were recorded in both WW and
TW. The concentrations of these elements are
considered lower than those recommended for
nutrient solutions in crop production (e.g.,
vegetables) under hydroponic systems
according to Benton (2005). Hydroponic green
fodder is usually grown with no or little added
fertilizers due to the short period of growth
(Al-Karaki and Al-Momani, 2010). However,
Al-Karaki and Al-Hashimi (2010)
recommended that no need to use fertilizer for
green barley fodder production under
hydroponic conditions, when they found that
chemical fertilization at 10% or 20% of
Hoagland's solution had no significant effects
on barley green fodder yield compared to no
fertilization (control).
Ghazi N. Al-Karaki
85
Table 1. The characteristics of treated wastewater and tap water used for irrigation in this study.
Parameter Tap water Treated wastewater
EC dS/m 0.48 1.13
pH 7.84 7.82
DO (mg/L) - 3.1
BOD5 (mg/L) - 10
COD (mg/L) - 25
NO3-N (mg/L) 10 30
Cl (mg/L) 23 134
PO4-P (mg/L) 5.44 5.53
Ca (ppm) 67.2 42.2
Mg (ppm) 16.6 16.1
K (ppm) 102 114
Na (ppm) 81.1 500
Zn (ppm) 0.013 0.025
B (ppm) 0.057 0.052
To know the potential risk of heavy metals
in irrigation water to plants and hence animals
and human beings, it is necessary to evaluate
their concentrations in WW. The heavy metal
concentrations of WW and TW used in this
study are presented in Table 2. Although the
nickel, cadmium, chromium, and lead contents
in WW are much higher than those in TW
irrigation waters, the levels of these elements in
WW are lower than the acceptable levels set
for irrigation water for crop production
according to FAO guidelines (FAO, 1992).
Table 2. Toxic elements content in water used for irrigation and the maximum concentrations of heavy
metals in treated wastewater allowed to be used for irrigation according to FAO (1992).
Metal Tap water
Treated
wastewater
Maximum
concentrations
_____________ ppm _______________
Chromium (Cr) 0.0039 0.0090 0.10
Cadmium (Cd) 0.0005 0.0032 0.01
Nickel (Ni) 0.0003 0.0063 0.20
Lead (Pb) 0.0041 0.0147 5.00
Microbial quality in produced fodder
Irrigation with wastewater can represent a
major threat to public health (of both humans
and livestock), food safety and environmental
quality. The microbial quality of wastewater is
usually measured by the concentration of the
two primary sources of water-borne-fecal
coliforms and nematode eggs (Ayers et al.,
1992). Presence of E. coli in irrigation waters
is used as indicator of fecal pollution as this
organism can pose a significant health risks
(Dufour, 1997). Results of analysis of produced
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86
barley fodder seedlings showed no presence of
any pathogenic microorganisms (Table 3).
However, in a study conducted by Al-Ghazawi
et al. (2008) using the same source of WW for
production of barley under field conditions,
they found no or low populations of some
pathogenic organisms in barley seedlings
grown in soil under field conditions (Table 3).
Table 3. Analysis of pathogenic microorganism counts in hydroponic and field grown barley irrigated
with treated sewage wastewater.
Parameter Counts
Barley grown
hydroponically
Barley grown in field
(Al-Ghazawi et al. 2008)
Total coliforms
Not found
4.3 MPN/g
E. coli
Not found
< 0.3 MPN/g
Helminthes eggs
Not found
Not found
Fodder yield
Significant differences among various
water treatments used in this study were found
in green and dry biomass traits (Table 1).
Higher yields of fresh green and dry matter
were recorded in plants irrigated with WW
than for TW (Figure 1 and 2). Table 4 shows
barley fodder yields (on fresh green and dry
weight basis) and plant heights at harvest.
Average green forage yield ranged from 224
tones/ha with tap water to around 320 tones/ha
with WW for one production cycle (9 days).
A total possible green fodder yield of 5600 and
8000 tons/ha/year can be achieved with the
hydroponic system (with 25 harvests per year)
using TW and WW in irrigation, respectively.
This is more than 66 and 94 times for TW and
WW, respectively, greater than the green
fodder yield obtained from conventional field
grown forage of 85 tons/ha/year. Ghaly et al.
(2007) reported that forage wheat grown
hydroponically has exceeded some
conventional forage crops (e.g. alfalfa) by 98
folds under irrigation with wastewater.
Table 4. Green fodder (fresh and dry) yield, plant height, and ratio of produced green fodder / initial
planted seed weight of barley fodder produced under hydroponic conditions and irrigated with treated
wastewater and tap water.
Water
Type
Fresh fodder
yield
Dry fodder
yield
Seedling
height
Ratio of produced
fodder / planted
seed weight
ton/ ha ton/ ha cm
TW 224 c* 37.9 c 18.7 c 4.74 b
WW mix 276 b 45.2 b 20.3 b 5.02 b
WW 320 a 54.4 a 22.7 a 6.00 a
* Means followed by the same letter(s) in each column are not significantly different
at 5% probability level.
Ghazi N. Al-Karaki
87
Figure 1. Green fodder ready for harvest (A) and harvested green barley fodder
with their root mats (B).
Figure 2. Green fodder biomass produced under irrigation with WW (A) was
higher than that irrigated with TW (B).
Results of this study showed that green
fodder produced with WW was higher by 40%
than that with TW. Similar trend has been
noticed for dry matter production (Table 4).
Al-Ajmi et al. (2009) found that total barley
fodder yield increased by 1.5 times when
irrigated with treated sewage water over yield
using tap water. Green forage production has
been reported to highly correlate to N content
of irrigation water (Azevedo et al., 2006),
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88
which conformed to the results of analysis of
water used in this study that indicated that WW
contains higher N than tap water.
The heights of barley seedlings obtained in
this study were significantly higher when
irrigated with WW than irrigation with other
types of water. The average barley seedling
height ranged between 18.7 cm (TW) and 22.7
cm (WW) at harvest. Similar values of plant
heights were reported by Al-Hashmi (2008)
who obtained barley plants of height 20-22cm
grown hydroponically and irrigated with tap
water. Barley green fodder produced in this
study was 4.74 to 6 times more than the initial
weight of sown seeds (Table 4). These values
are comparable with the ones reported by
Sneath and Mclntosh (2003). Al-Hashimi
(2008) obtained slightly lower ratios of barley
produced fodder to planted seeds weight using
tap water in irrigation. However, Al-Karaki
(2008) reported that this ratio reached up to 8
times in barley green fodder produced
hydroponically.
Water use efficiency
Hydroponically produced fodder was found
to enhance the efficiency of water use (WUE).
Brandley and Marulanda (2000) reported that
hydroponic green fodder production technique
requires only about 10-20% of the water
needed to produce the same amount of crop in
soil culture. While Al-Karaki (2010) reported
that only 3-5% of water is needed to produce
the same amount of fodder in comparison to
that produced under field conditions. In this
study, barley plants had utilized 25% more
water when irrigated with TW than with WW,
while dry matter production with WW was
higher than TW by about 28% (Table 5). This
improvement in crop yield might be
appreciable and economically feasible.
Irrigation with WW was found to use water
more efficiently in producing green fodder than
irrigation with the other two types of water
(TW and WW mix) when used only 1.26 m3
water to produce 1 ton of hydroponic green
fodder in comparison to 1.38 and 1.56 m3 water
in WW mix and TW, respectively (Table 5).
Similar data were revealed by other researchers
(Al-Hashmi, 2008; Al-Karaki and Al-Momani,
2010).
Table 5. Total water use and water use efficiency of barley fodder produced under hydroponic
conditions and irrigated with different water types.
Water type Water use Water use efficiency
m3 / ton fresh matter
ton fresh matter / m3
ton dry matter / m3
TW 1.56 a* 0.641 b 0.108 b
WW mix 1.38 b 0.725 a 0.119 b
WW 1.26 b 0.794 a 0.136 a
* Means followed by the same letter(s) in each column are not significantly different
at 5% probability level.
Producing green fodders under hydroponic
conditions is a highly efficient process in term
of water saving when compared to field
production of green fodders as the production
of 1 kg of barley green fodder under field
conditions needs 73.5-167 liters of water (Al-
Karaki, 2010). Al-Karaki and Al-Momani
(2010) reported that only 14 kg fresh matter/m3
water were obtained for field irrigated barley,
compared to about 680 kg fresh matter/m3
water obtained in this study. This is a
tremendous improvement in WUE and
Ghazi N. Al-Karaki
89
indicated that hydroponic system could play a
significant role in improving water use
efficiency in Jordan and other countries in the
region with shortage in irrigation water.
Fodder quality
The proximate analysis for the produced
dry fodder showed higher contents of crude
protein, neutral (NDF) and acid detergent fiber
(ADF) in WW in comparison with barley
fodder irrigated with other types of water
(Table 6). The protein content in
hydroponically produced fodder reached about
27.4% irrigated with WW, while the values of
barley fodder irrigated with WW mix and TW
were 24.9% and 25.2%, respectively (Table 6).
However, no significant differences were
determined between crude fiber and crude fat
content in the fodder irrigated with three types
of water (Table 6). The values of ADF and
NDF in dry fodder ranged between 11-13.4%
for ADF and between 28.8-32.7% for NDF
(Table 6). Owens (2009) reported that the
lower values of ADF (<30%) and NDF (<40%)
in the fodder are considered of good nutritional
values. The findings related to produce green
fodder in this study indicated that irrigation
with WW or WW mix may have no adverse
effect on health or performance of grazing
animals. It offers good use of treated
wastewater to increase farmers' benefits.
Proximate chemical analyses indicated that
barely fodder may probably be superior in
some aspects to field grown alfalfa hay used
mainly as a source of roughage for livestock in
Jordan and the countries of region. Al-Karaki
and Al-Momani (2010) reported that
hydroponic barley fodder has higher crude
protein values and less fiber content than field
grown alfalfa forages. Dry matter content in
the produced fodder in this study ranged
between 16.4% and 17.1%, and these values
are not significantly different between different
barley fodders irrigated with different water
types (Table 6). The nutrient requirements of
the seedlings are quite or partially satisfied
from the reserved compounds in the seeds
(Bewley, 1997).
Table 6. Proximate analyses of barley irrigated with treated wastewater (WW), tap water (TW) or
mixture of WW and TW under hydroponic conditions (dry matter basis).
Water type
Crude
protein Crude fat
Crude
fiber
Acid
detergent
fiber
Neutral
detergent
fiber
Dry
matter
content
____________________ % __________________
Tap water 25.2 b* 5.2 a 14.3 a 11.7 b 28.8 b 16.4 a
WW mix 24.9 b 5.4 a 15.5 a 13.4 a 32.7 a 16.9 a
WW 27.4 a 4.8 a 15.6 a 13.1 a 31.2 ab 17.1 a
* Means followed by the same letter(s) in each column are not significantly different at 5% probability level.
Nutrient mineral content in barley fodder
Minerals have a major nutritional
significance for livestock and feed deficiencies
in elements, such as Ca, Fe, Mn, Zn, can lead
to a variety of health problems from anemia to
osteoporosis (Liu et al., 2007). Concentration
of nutrient elements analyzed in dry barley
fodder is presented in Table 7. Except for N,
Mg, and Na, there were no significant
differences in concentrations of the analyzed
elements (P, K, Ca, Zn, and Mn) between those
irrigated with WW and with tap water or WW
mix. The short growing period of barley
fodder under hydroponic conditions and its
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90
dependency on its own reserved compounds for
the early growing stages may be attributed to
the low variations of mineral nutrients in the
produced fodder irrigated with WW and tap
water. The nutrient requirements of the
seedlings after germination are quite low and
partially satisfied from the reserved compounds
in the seeds (Bewley, 1997).
Table 7. The concentration of mineral nutrients in barley green fodder produced under hydroponic
conditions and irrigated with different water types (dry matter basis).
Water
type N P K Mg Ca Na Zn
Mn
_____________________(mg/g) _________________ _____(mg/kg) ____
TW 40.3 b* 6.05 a 8.63 a 3.78 b 3.19 a 2.50 c 5.58 a 9.5 a
WW mix 39.8 b 5.65 a 9.39 a 4.05 a 2.94 a 2.84 b 6.14 a 11.7 a
WW 43.8 a 5.52 a 9.26 a 4.12 a 2.68 a 3.10 a 5.36 a 12.1 a
* Means followed by the same letter(s) in each column are not significantly different at 5% probability level.
The high concentrations of N and Mg in
dry fodder irrigated with WW might be due to
their high concentrations in the WW used for
irrigation. This might indicate that the WW is
a good source of these minerals that can be
used for irrigation under hydroponic
conditions. Na levels increased significantly in
barley fodder irrigated with WW or WW mix.
This is may be a result of their high
concentrations in WW used for irrigation. Al-
Ajmi et al. (2009) reported that except for Ca,
no significant differences were found between
the fodder irrigated with treated wastewater
and tap water for the nutrient elements N, P, K,
Ca, and Fe contents. Compared to the long
term effect of WW irrigation, Rusan et al.
(2007) reported that N, P, K, Cu, Zn, Fe, and
Mn increased significantly in soils as years of
WW irrigation increased in the same lands.
Generally, the results of this study indicated
that the contents of those essential minerals
were available in the produced green fodder
around their usual level, thus, WW can be used
for irrigation under hydroponic conditions
without any adverse effects regarding to these
elements.
Heavy metal content in fodder
Application of WW in irrigation crops
usually contain elevated levels of heavy metals
(specifically Cd, Ni and Pb) which might
accumulate in fodder and cause toxic effects on
human by affecting animal products due to
direct intake of contaminated fodder (Adriano,
2001). Cadmium concentration in barley
fodder was higher in WW than TW or WW
mix irrigated plants (Table 8). Cadmium levels
found in barley fodder ranged between 0.020
ppm (in tap water) and 0.032 ppm (in WW).
These are below the limits set by WHO and
FAO which are 0.2 mg/kg fresh weight for
leafy vegetables and fresh herbs (WHO/FAO,
2007).
The low accumulation of Cd in barley
tissues may be attributed to the slightly basic
nature of the WW water. Nickel concentrations
in barley fodder ranged between 0.057 ppm
(tap water) and 0.47 ppm (WW) (Table 8).
These are below the limits by FAO for edible
crops (FAO, 1992). However, Ni is considered
an essential element for small grains (e.g.,
barley).
Lead (Pb) level in dry fodder was higher in
those plants irrigated with WW, ranging
between 0.433 ppm (tap water) and 0.903 ppm
(WW) on dry matter basis. These levels are
lower than those reported by Kabata-Pendias
(2000) and Finister et al. (2004) for edible
crops. No significant differences were noted
for Cr in dry fodder regardless of water type
used in irrigation (Table 8).
Ghazi N. Al-Karaki
91
Table 8. The concentration of heavy metals (ppm) in green barley fodder produced under hydroponic
conditions and irrigated with different water types.
Pb Ni Cr Cd
Water type _____________ ppm _________________
TW 0.433 c* 0.057 c 0.11 a 0.020 c
WW mix 0.647 b 0.240 b 0.09 a 0.028 b
WW 0.903 a 0.47 b 0.08 a 0.032 ab
Safe limits in plants
(vegetative parts) 5.0† 1.5‡ 20‡ 0.2†
* Means followed by the same letter(s) in each column are not significantly different
at 5% probability level.
† according to WHO/FAO (2007)
‡ according to Awashthi (2000)
Conclusions
Hydroponic system is a potential technique
for barley fodder production with less water
consumption where water is the main limiting
factor for agricultural production (e.g., Jordan).
Tertiary treated sewage wastewater is a feasible
source for irrigation of hydroponically
produced barley fodder. The current study
shows the superiority of WW irrigated fodder
barley over that irrigated with tap water in
several aspects related to production and
quality of the produced barley crop. This
indicated that WW is a good source of nutrients
needed for plant growth to promote high yields.
The accumulation of heavy metals in the
fodder irrigated with WW was apparent, yet
below FAO accepted limits. The use of WW in
hydroponic systems may reduce the risk of
heavy metal accumulation in the soil with
prolonged use. It is also considered an
environmentally sound waste water disposal
practice compared to direct disposal into
surface or ground water bodies.
Acknowledgments
The author is grateful to the Deanship of
Scientific Research at Jordan University of
Science and Technology (Jordan) for funding
this research.
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