沙漠研究 24-1, 85-88 (2014)
Ἃ₍◊✲ 24-1, 85 - 88 (2014)
Journal of Arid Land Studies
Journal of Arid Land Studies－ DT11 Refereed Paper －㸫DT11 Refereed Paper㸫

Salts Monitoring and Management for Human Urine Fertilization and Treated
Greywater Irrigation in Sub-Sahel Region
Nowaki HIJIKATA*1), 2), Takahisa FUJII2), Drissa SANGARE1), Mariam SOU1),Ken USHIJIMA2) and Naoyuki FUNAMIZU2)
Abstract: Human urine and greywater are available as liquid fertilizer and irrigation sources. However, salt in the materials might
accumulate in soil, particularly in semi-arid regions, such as the sub-Sahel. Salt loading was monitored in pilot gardens where urine
and greywater were reused. Sodium distribution was observed in a pot scale experiment to assess the potential of leaching andphytoremediation by sorghum during rainy season cultivation. The chemical properties and usage estimation of the urine andgreywater inferred that applied Na and major cations in pilot-garden might be mainly derived from greywater. Salt monitoring inpilot-gardens showed that soil SAR in two sites decreased significantly and in others remained stable during the reuse cultivation.
Sorghum culture under sufficient irrigation showed that leaching potentially contributed to Na removal compared to phytoremediation.
Supplemental amendment of gypsum and ash as Ca agents did not affect the Na removal. Therefore, we concluded that Na might bepotentially removed by leaching in rainy season, when urine and greywater were reused under semi-arid zone.
Key Words: Human urine, Leaching, Phytoremediation, Salts accumulation, Sorghum

1. Introduction
Human urine and greywater, which is domestic waste
water except human excreta, have been recognized as potential
resources for agriculture as nutrients and irrigation. This
reuse, particularly, would be an attractive option for small scale
farmers in sub-Sahel regions, who suffer from limited
irrigation resources and poor access to chemical fertilizers.
Separation of human feces from urine and greywater would
reduce the organic load and pathogens (Lopez et al., 2002).
Thus, the separation simplifies each treatment which leads toreduced overall investment for sanitation (Winblad, 2004).
Although many have shown the advantage of urine
fertilization for various crops and vegetables because of its
nutrient elements (Kirchmann and Pettersson, 1995; Mnkeni etal., 2008; Mullegger et al., 2010), it has been also reported thaturine fertilization caused competitive uptake of potassium (K)and sodium (Na) in plants (Pradhan et al., 2010; Sene et al.,2013) and excessive urine application inhibited plant growth
due to increasing soil electrical conductivity (EC) (Mnkeni etal., 2008). Furthermore, greywater also contains undesirable
components such as Na, oil and surfactants (Wiel-Shafran et al.,2006; Al-Hmaiedeh and Bino, 2010; Travis et al., 2010).
Long term irrigation with greywater leads to increased soil EC
and sodium adsorption ratio (SAR) (Al-Hamaiedeh and Bino,* Corresponding Author: nowaki@eng.hokudai.ac.jp

2010). This might cause low water permeability andcompacted soil. Furthermore, oil and surfactant accumulation
in soil potentially disturbs water permeability and capillarity(Wiel-Shafran et al., 2006; Travis et al., 2010). Althoughsimple greywater treatment facilities have been developed thatsuccessfully remove organic matter, surfactants and pathogens(Al-Hamaiedeh and Bino, 2010; Ushijima et al., 2013), thefacilities allowed soluble minerals, such as Na+, to pass though.
Therefore, salt monitoring and management of fields isessential when the urine and greywater are reused especially in
sub-humid and semi-arid zone, where applied minerals areeasily accumulated in soil surface due to high evaporation.
In order to remove excess salts from soil, leaching with
sufficient irrigation, amending with gypsum or
phytoremediation have been proposed (Qadir et al., 2005).
Small scale farmers in sub-Sahel region lack sufficient water
resources, appropriate irrigation systems and funds to purchasegypsum in the local market. Thus, we hypothesize rainfall
may provide sufficient irrigation, sorghum may serve as a
remediation plant and ash derived from cook stoves canfacilitate Na removal. In the present study, we monitored salt
accumulation in pilot-gardens of small scale farmers, who
amend their vegetable gardens with their own urine andgreywater, in rural Burkina Faso.
Additionally, Na
distribution was observed in a pot experiment to determine Na
phytoremediation and leaching capacity.
㸦Received, September 15th, 2013; Accepted, November 26th, 2013㸧

01 BP 594, Ouagadougou 01, Burkina Faso
1) Department of Teaching and Research in Water Efficiency Management and Sanitation, International Institute for Water and Environmental Engineering (2iE), Burkina Faso
2) Department of Environmental Engineering, Graduate School of Engineering, Hokkaido University, Japan86

2. Materials and Methods
2.1.1. Pilot-garden
Six pilot-gardens (KB1, KB2, KD1, KD2, BK1 and BK2)
of 50 m2, of small scale farmers in rural Burkina Faso, werelocated on their premises. Experiments were conducted fromthe end of June to the first of October 2012. Okra andeggplant were cultivated with the farmers own urine andgreywater. The urine was separately collected, stocked for a
few months, and applied 3 times during the growing season (atthe rate of 0.5 L, 0.5 L and 0.3 L per one plant; totally 1.3
L/plant, 7.8 L/m2). The greywater was treated by a slanted
soil system (Ushijima et al., 2013). The applied amount wasestimated by questionnaire survey of the family. Total
minerals input of urine and greywater were estimated with theapplied amount and its concentration described as below.
2.1.2. Chemical property of urine and greywater
Source-separated urine and treated greywater were
sampled before and after cultivation. pH and EC value in theurine and greywater were measured by electrode. Chemical
oxygen demand (COD), total nitrogen (N) and total
phosphorus (P) were measured with Hach kit (DR6500, Hach);and potassium (K), calcium (Ca), magnesium (Mg), sodium(Na) and minor cations were determined ICP-AES (ICPE 9000,
Shimazu) after filtration (0.45 ȝm pore, ADVANTEC). SAR
was calculated with following equation:
SAR =2.1.3. Chemical property of pilot-garden soil
Pilot-garden soil was sampled in July and October. Soil
pH (1:2.5) and EC (1:5) were measured after 3 hours shaking
with pure water. In the case of SAR in soil, soil was saturated
with pure water (1:10) and the soil suspension was centrifugedat 3000 rpm for 10 min and the supernatant filtered with 0.45
ȝm membrane filter (ADVANTEC). Na, K, Ca and Mg inthe filtered samples were determined by ICP-AES.
2.1.4. Pot experiment
A pot experiment was conducted in a greenhouse withsorghum as a model of a phytoremediation plant. Assumed
as pilot-garden soil which Na was accumulated, red ocher
color soil (en-tout-cas; clay particles of crushed brick) andblack soil was mixed at the ratio of 3:1. The calcium andmagnesium ratio in the soil mixture was adjusted at 10:1 withmagnesium sulfate, and the SAR value was adjusted to 6 withsodium hydrogen carbonate. The pH and EC of the soil
mixture was 7.74 and 3.48, respectively. The soil (2 kg) was
mixed with 37 g (dry base) of compost in a plastic pot (200cm2 surface, 159ĳ × 190 mm depth). Polyvinyl tubing wasconnected to a drain of the pot and leachate was collected. To
determine the effect of Ca on Na-removal, 9.56 g of ash(corresponded 0.42 g-Ca) or 2.62 g of CaSO4 (gypsum, 0.42g-Ca) were applied. Five replications of each treatment wereprepared. Germinated sorghum seeds (6) were transplantedin the pot, and thinned to two plants per pot after two weeks.
Mimicking precipitation from July to August in Ouagadougou,
Burkina Faso, the pots were irrigated with tap water and theamount was 75 ml/day for first two weeks and 150 ml/day
afterwards. Eight weeks after planting, sorghum stem andleaf were harvested and oven dried at 60°C for 5 days todetermine dry weight.
2.1.5. Sorghum and leaching water cation
Leachate from each pot was collected every two weeks anddetermined the weight. K, Ca, Mg and Na concentration in
the leachate were determined by same method with greywater
analysis described above. Total amount of leached cations
was calculated as a sum from one pot during planting period (4times sampling) and the each mass was calculated with theleachate weight and its concentration. Dried sorghum
samples (0.25 g) were ground with mortar and pestle, digested
by nitrate and hydrogen peroxide at 140°C, diluted and filtered.
The sample cations concentration was determined by ICP-AES
as described above. Cation content in the shoot wascalculated with the concentration and the dry weight. To
observe early Na stress symptom (Tuna et al., 2007), K/Na and
Ca/Na ratio was calculated with the concentration in sorghum.
2.1.6. Statistical analysis
Statistical analysis was conducted with IBM SPSS statistic
21 software. Significant difference of pilot-garden soil before
and after vegetation was evaluated with t-test (p<0.05).
Significant difference of Ca treatments in pot experiment wasevaluated with ANOVA and Tukey-HSD test (p<0.05).

3. Result and Discussion
3.1.1. Quality of urine and greywater in pilot-garden
Chemical properties of urine were shown in Table 1. N,
P and K in source-separated storage urine of 6 pilot-families,
were 3.6 ± 0.7 g/L, 0.7 ± 0.3 g/L and 0.6 ± 0.3 g/L, respectively.
In the case of minor cations, only boron and iron was detected.
Others found these chemical properties varied from 1.7-8.4
g-N/L, 0.3-0.8 g-P/L, 0.9-2 g-K/L and 2.3-9.0 g-Na/L(Kirchmann and Pettersson, 1995; Mnkeni et al., 2008; Pradhan
et al., 2010; Mullegger et al., 2010). The present results weresimilar and most of values were inside of these ranges.
Differences among samples reflect family lifestyle, foodculture or differences in rainfall contribution. Similar to theurine, chemical properties of greywater also varied particularly
in EC, SAR, COD, total N and Na (Table 2). The ranges werealso followed by a previous report (Al-Hamaiedeh and Bino,2010). However, relatively high bacteria were observed. Thismight be caused by lack of on-site maintenance. Therefore,
simplified maintenance should be further investigated.

87

Table 1. Chemical properties of urine.
ppH
H
EC [dS/m]
SSAR
AR
Total N [g/L]
Total P [g/L]Na [g/L]K [g/L]Ca [mg/L]
Mg [mg/L]
B [mg/L]
Fe [mg/L]
Zn [mg/L]
Mn [mg/L]
Cu [mg/L]
E. coli [cfu/ml]
Total Coliform [cfu/ml]

Min
88.6
.6
20.7
88.5
.5
2.4
0.4
0.8
0.4
2.0
2.0
0.5
n.d.
n.d.
n.d.
n.d.
n.d.
n.d.

Max
99.0
.0
37.1
336.2
6.2
4.4
1.2
2.3
1.2
26.3
32.8
2.0
1.3
n.d.
n.d.
n.d.
n.d.
n.d.

Mean
88.8
.8
28.1
115.2
5.2
3.6
0.7
1.3
0.6
10.9
10.1
1.1
0.3
-

STDEV
00.1
.1
7.1
110.6
0.6
0.7
0.3
0.7
0.3
9.1
11.5
0.6
1.7
-

Fig. 2. Change of soil EC in pilot-gardens before and after vegetation.

Table 2. Chemical properties of treated greywater.
ppH
H
EC [dS/m]SSAR
AR
COD [mg/L]
Total N [g/L]
Total P [g/L]Na [g/L]

Min

77.1
.1
-1
-1
4.7x10
00.7
.7
42
-2
-2

Max
88.4
.4
1.5
33.0
.0
195

Mean
77.8
.8

-2
-2

-1
-1

STDEV
00.4
.4

-1
-1

8.5x10
11.8
.8
79.4

2.8x10
00.7
.7
46.3

-2
-2

-2
-2

1.0x10-4-4
1.3x107.7x10-3-3
7.6x103.3x10-3-3
2.1x101.9x10-3-3
2.2x10

-2
-2

-1
-1

-2
-2

-2
-2

2.3x101.1x106.1x102.4x10K [g/L]Ca [mg/L]
Mg [mg/L]
E. coli [cfu/ml]

2.2x1028.4
3.7
4.0x104.5x1042.6
22.2

3.3x1035.7
12.4

1.0x106.9
5.8

22

2.2x103.0x106.3x10Total Coliform [cfu/ml]

8.0x103.3x105.1x109.3x10

-2
-2

-2
-2

44
55

-2
-2

33
44

-2
-2

33
44

Fig. 1. Estimated total mineral input from urine and greywater.

3.1.2. Estimation of total mineral input into pilot-garden(Fig. 1)
From the survey with pilot-family, the total input of
irrigation was estimated at 2.6-9.0 (mean 5.7 ± 2.7) L/m2/day.
The impact of greywater on the major cations input was higher
than urine and large amount of Na was derived from greywater.
Even the combined application of urine and greywater, total
phosphorus was insufficient for okra and eggplant. Sene et al.
(2012) showed low phosphorus content of plant in urine reuse.
Therefore, it was suggested that additional materials such as
wood ash (Pradhan et al., 2009, 2010) or human feces (Guzha
et al., 2005) would be beneficial for vegetable production.
3.1.3. Salt monitoring in soil of pilot-garden
Soil EC in KD2 and BK1 site increased significantly frombefore cultivation to after cultivation (Fig. 2). EC at othersites did not change significantly. High urine application
elevates soil EC (Mnkeni et al., 2008; Sene et al., 2013), but

Fig. 3. Change of soil SAR in pilot-gardens before and after vegetation.

smaller urine applications did not alter soil EC more thanchemical fertilizer (Pradhan et al., 2009, 2010). Furthermore,
greywater irrigation also increases soil EC (Weil-Shafran et al.,2006; Al-Hamaiedeh and Bino, 2010).
Therefore, thecombination application of urine and greywater has the potential
to increase soil EC value even during the rainy season.
Soil SAR in pilot-garden responded differently than soil
EC with two sites (KD1 and KD2) observing a decrease in
SAR over the course of the experiment (Fig. 3). All otherlocations did not observe a change in SAR. Soil SAR has
been shown to increase with large amount of urine (Sene et al.,2013) and long-term greywater irrigation (Al-Hamaiedeh andBino, 2010) with less irrigation and rainfall than this experiment.
3.1.4. Distribution of Na and salt management
In the pot experiment, sorghum shoot dry weight of control,
ash and CaSO4 was 1.0, 1.0 and 0.8 g after 60 days,
respectively (Fig. 4). The CaSO4 treatment was significantly
lower than the others. Shoot K content was lower with the+CaSO4 treatment the control or +Ash. Ca, Mg and Na shootcontent were not affected by treatment (Table 3). K/Na and
Ca/Na ratios are not different among amendment treatments.
Leaching amount of Ca, Mg and Na were not different among
amendment treatments (Table 4). However, leached Ca, Mg
and Na were higher than plant uptake. In the case of Naleaching, particularly, the amount was more than thousand
times higher than plant uptake. This indicates the capacity of
Na leaching under sufficient irrigation was much larger thanphytoremediation or the effect of Ca amendment on Na
removal. Similar results have been reported by Qadir et al.
(2003) who showed larger contribution of Na leaching88

References

Fig. 4. Shoot dry weight of sorghum with sufficient irrigation.
Table 3. Cation shoot content 60 days after treatment.
K [mg/pot][mg/pot]
K
Ca [mg/pot][mg/pot]Ca
Mg [mg/pot][mg/pot]
Mg
Na [mg/pot][mg/pot]
Na

Control
Control
5.0±0.5a
5.0±0.5a
4.5±1.6
4.5±1.6
2.6±0.3
2.6±0.3
0.29±0.14
0.29±0.14

+Ash
+Ash
5.0±0.4a
5.0±0.4a
4.3±0.1
4.3±0.1
2.7±0.2
2.7±0.2
0.17±0.03
0.17±0.03+CaSO44+CaSO4+CaSO
3.7±0.1b
3.7±0.1b
3.2±0.6
3.2±0.6
2.3±0.3
2.3±0.3
0.14±0.08
0.14±0.08

K/Na
K/Na
Ca/Na
Ca/Na

19.7±11.4
19.7±11.4
19.0±14.6
19.0±14.6

27.3±3.3
27.3±3.3
23.4±4.1
23.4±4.1

33.0±15.2
33.0±15.2
29.6±15.6
29.6±15.6

Table 4. Total amount of leached cations.
Ca [mg/pot][mg/pot]Ca
Mg [mg/pot][mg/pot]
Mg
Na [g/pot][g/pot]Na

Control
Control40.0±1540.0±1525.1±10.925.1±10.9
7.6±1.2
7.6±1.2+Ash+Ash
41.9±21.4
41.9±21.4
32.9±13.1
32.9±13.1
6.4±0.9
6.4±0.9+CaSO44+CaSO4+CaSO
77.7±9.877.7±9.840.8±5.0
40.8±5.0
5.9±0.5
5.9±0.5

compared to Na phytoremediation.
The present experiment was conducted under the following
conditions; (i) artificial soil mixture which chemical parameter
were adjusted with reagent powder, (ii) plastic pot which had
only 20 cm depth. Compared to the experimental condition,
the real pilot-garden was different in that; (i’) natural soil
constructs complicated precipitation and the soil might belower permeability (ii’) leached water would rise up by
capillary force after irrigation and rainfall or water could flush
nutrients through the soil profile or lost through run-off.
Therefore, more detail monitoring in pilot-garden or fields andmore specific and larger scale experiment could be required to
manage salt accumulation with urine and greywater reuse.

4. Conclusion
The present study aimed to monitor salt accumulation inpilot-gardens where human urine and treated greywater werereused and to observe a capacity of Na-leaching andNa-phytoremediation. Soil SAR may be of lesser concern
when using urine and greywater during periods of rainfall, but
sodium related problems may be a larger concern when thesealternative water sources would be in higher demand during
periods of low rainfall. Therefore, additional techniques for
Na removal should be further investigated.

Acknowledgement
This study was supported by SATREPS (JICA/JST).

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