沙漠研究 19-1, 327- 330 (2009 )Journal of Arid Land Studies“Desert Technology IX ”
Refereed Paper

Olive mill waste water valorisation in agriculture-Effects on the soil proprieties and barley yieldRaja DAKHLI1, Houcine TAAMALLAH1, Kamel NAGAZ1, Ridha LAMOURI1
Abstract: The spreading of olive mill waste water (OMWW) on sandy soil in Southern Tunisia
represents an interesting alternative and new method for the treatment and the valorisation of thiseffluent. The main aim of this study was to investigate the use of OMWW as a fertilizer for
Barley cultivation. In fact, the application of 50 (T1), 100 (T2) and 200 (T3) m3/ha of thiswastewater resulted in a significant improvement of the soil fertility. Indeed, the ratio
carbon/nitrogen increased from 9 for the control to more than 22 for the T3 treatment. The
potassium content showed also a considerable improvement (From 300 mg/kg for the control tomore than 1988 mg/kg for the treatment T3). Because of its binding and hydrophobic effects, theapplication of OMWW resulted in a more stable soil and created mulch reducing the losses ofwater evaporation.
Regarding the production, compared to the control and after the spreading operation, adecreased seed yield has been recorded. In fact, compared to the control (1262.2 kg/ha), the seed
33yield recorded a clear decrease for the treatment 100 m /ha (762.9 kg/ha) and 200 m /ha 362.2
3kg/ha). However, treatments of 50 m /ha recorded a light increase (1362.2 kg/ha). It was
concluded that the OMWW applied with high doses (100 and 200 m3/ha) reduce the production
whereas the low doses (under 50 m3/ha) improve the soil characteristics. Then, it is recommendedthat the OMWW can be applied with amounts less than 50 m3/ha for Barley cultivation.
Key words: Barley, Olive mill wastewater, Seed yield, Soil, Valorization.

1. Introduction
Olive oil extraction produces large amounts of waste water, known as olive mill waste water(OMWW). This effluent has a high chemical oxygen demand, contains high level of phenolic compounds,
and is therefore a cause of environmental pollution. In fact, the olive oil waste water (OMWW) constitutes
serious environmental problems in Tunisia and in the world because of their high concentrations ofpolyphenols and other pollutants. The exploitation of this waste without preliminary treatment is very
limited considering its toxicity for soils and plants. In Tunisia, 700,000 tons of OMWW, produced
annually, are generating many types of pollution. They are dried in special basins and then put in heap to
be used as compost while an important fraction of the product is poured directly in the natural channel beds
(wadi). However, the richness of that sludge in mineral and organic compound raised to investigate othertechniques to valorise this residue in agronomy. This work fits into this context and aims to study theimpact of the spreading of OMWW on the physical and chemical soil properties and its effects on cropyields (Case of barley).
2. Materials and Methods
2.1. Experimental site
The experiments were conducted in the farmer located in the El FJE area (Medenine, Tunisia). The
soil is characterised by a low organic matter and a sandy texture. It is also characterized by a high level ofthe electrical conductivity which increases with the depth. Indeed, this parameter increased from 5 dS/m insurface layer to more than 8 dS/m in depth (see Table 1). This salinity increase can be explained by anincrease in the soil gypsum content since the bedrock is formed by the miopliocene clay and gypsum at thehorizon 70-80 cm. OMWW was obtained from a local olive oil manufacture. Physical and chemical
characteristics of the used effluent are presented in Table 2. The plant material is used with 2 barleyvarieties, Hordeum vulgare Ardhaoui and Pakesteni (Introduced variety).

1

Institut des Régions Arides - 4119 El Fjè - Medenine - Tunisia

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Table 1. The main physical and chemical characteristics of soil.

Depth(cm)

Clay

0-25
25-50
50-75

3.57
3.77
4.88

Silt(%)
5.20
6.20
7.25

(%)

Sand (%)
69.43
63.78
53.45

17.77
5.13
29.54

InitialEC(ds/m)
6.65
5.43
6.79

5.67
7.99
8.79

CaCO3
Total (%)
5.55
8.33
8.33

Gypsu
m (%)
0.37
1.5
3.45

Organicmatter (%).
0.92
0.88
0.54

pH
7.11
7.23
7.15

Table2: Principal physical and chemical properties of OMWW

DR=dry matter;
MM=Mineral Matter;

pHDR (%)

OM (%)

MM (%)EC (ms/cm)

4,77

30

83

1716.61

OM=Organic Matter;
EC=Electrical

Conductivity.

113PA

PA

P

A

PTPPA

PA

P

A

PTT

P

13PA

PA

P

A

PT

T

A

3PP

A

P

A

PTT

A

A

PPA

PA

P

T

T

A

A

T

T

A

P

A
A
A
T

A

P

Fig. 1. Experimental design.

2.2. Experimental design
The adopted experimental design is the randomized block with 4 treatments of OMWW (Controltreatment: T0=0 m3/ha; T1=50 m3/ha; T2=100 m3/ha; T3=200 m3/ha), 2 varieties of barley: Ardhaoui (A)and Pakesteni (P) in 3 repetitions
2.3. Studied parameters
Effect of OMWW on chemical and physical soil properties (organic matter, K exchangeable electricalconductivity, pH and soil content in Sodium, Chloride and Sulfate). Evaluation of Barley yield.
2.4. Statistical analysis
All statistical analysis was conducted using the SAS System for Windows version 9.00.
3. Results and discussion
3.1. Effect of OMWW on chemical and physical soil propertiesOMWW application does not affect the soil pH because of the high concentration in limestone
making a power buffer for the incorporated acidic products in the soil (Ros de Ursinos F 1996). The
application of OMWW on alkaline and limestone soils, frequent in the Mediterranean areas, do not affectthe soil pH (Levi-Minzi et al., 1992). Spreading OMWW leads to a significant increase in soil salinity.
Indeed, from an electrical conductivity less than 5 dS/m (The Control), the soil salinity increases to morethan 7 dS/m for the plot that received the highest dose (T3: 200 m3/ha). The difference is statisticallysignificant especially for higher doses (T2 = 100 m3/ha and T3 = 200 m3/ha). Sodium increases with theadministrated OMWW doses. Compared to the control (5662 mg/Kg), the Sodium content showed aconsiderable improvement for the treatment T2: 200 m3/ha (7837.83 mg/Kg) and T3: 200 m3/ha (10640.8A

329(a)

(b)

(d)

(c)

(e)

Fig. 2. Effect of OMWW on soil pH (a), on soil electrical conductivity (b), on soil ratio Carbon/Nitrogen (c), on
soil K exchangeable concentration (d) and on soil Content in Sodium, Chloride.and Sulphate (e).

(I)

(II)

Fig. 3. Effect of spreading OMWW on Barley dry matter (I) and seed yield (II).

mg/Kg). However, Chloride and Sulphate recorded an increase in soil without being statistically different
for the control. The rate of organic matter increases with the doses administrated. Indeed, the ratio
carbon/nitrogen increases from 9 for the control to more than 22 for the T3 treatment. The potassium
content showed also a considerable improvement (From 300 mg/kg for the control to more than 1988
mg/kg for the T3 treatment). Because of its binding and hydrophobic effects, the application of OMWW
resulted in a more stable soil and created mulch reducing the losses of water evaporation. The applicationof 50 m3/ha (T1), 100 m3/ha (T2) and 200 m3/ha (T3) m3/ha of this wastewater resulted in a significant
improvement of the soil fertility (Taamallah, 2007).
3.2. Effect of OMWW on Barley yield
The results showed that the yield of both grain and dry matter was affected by OMWW supplies.
Regarding the production, compared to the control and after the spreading operation, a decreased grain
yield has been recorded. In fact, compared to the control (1262.2 kg/ha), the seed yield recorded a clear
decrease for the treatment 100 m³/ha (762.9 kg/ha) and 200 m³/ha 362.2 kg/ha). However, treatments of 50
m³/ha recorded a light increase (1362.2 kg/ha) without being statistically different from the control. The
application of OMWW has affected also Barley dry matter yield for treatments 100 m³/ha (T2) and 200
m³/ha (T3). OMWW cause a light decrease of dry matter production for respectively 100 m³/ha and 200m³/ha treatment (768.3 kg/ha and 637 kg/ha) compared to the control (1600 kg/ha).

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4. Conclusion
Containing many nutritive elements leading to an improvement of agricultural production, OMWW
can be considered as a fertilizer for Barley cultivation. Indeed, used with amounts less than 50 m³/ha,
OMWW do not present any risks for the soil salinity, the phenolic substances concentration, the potassium
content and acidity. In addition, they generate an improvement of some physical and chemical soil
properties and an increase in the barley yields whereas a spreading with strong amounts of the OMWW
causes an ionic imbalance and an increase in the soil salinity. It was concluded that the OMWW appliedwith high doses (100 and 200 m3/ha) reduce the production whereas the low doses (less than 50 m3/ha)
improve the soil characteristics. It provides an economically acceptable production alternative for Barleycultivation and can reduce the problems caused by this effluent.
References
Levi Minzi R., Saviozzi A., Riffaldi R., Falzo L. (1992): L’épandage au champ des eaux de végétation, effets sur les propriétés dessols. Olivae, 40: 20-25.
Ros de Ursinos F., Berndt L., Geissen K., Kachouri M., Klimm E. (1996): Les expériences méditerranéennes dans le traitement etl’élimination des eaux résiduaires des huileries d’olives. Coopération Tunisie-Allemagne. 380 p.
Taamallah H. (2007): L’épandage des Margines au niveau des champs d’oliviers : une alternative pour la valorisation de ceteffluent des huileries d’olives. Thèse de doctorat (Ph.D), facult de sciences en bio ingéniérie, université de Gent, p180.