沙漠研究 19-1, 335- 338 (2009 )Journal of Arid Land Studies“Desert Technology IX ”
Refereed Paper

Impact of Irrigation with Saline Water on Soil and Crop Yields-El Fjé Region MedenineIbtissem ENNEB1, Houcine TAAMALLAH1, Abdessatar HATIRA2
Abstract: The main objective of this study was to follow the soil saltiness and its effect on hisphysical and chemical characteristics following the irrigation by brackish water as well as thetolerance of some varieties to salt. The water used for irrigation comes from a boring thatpumps water from the water table of wadi el Fjé (Medenine, Tunisia). The flow of pumping isestimated to 15 l/s. This brackish water has a high salinity with more than 8 dS/m as electricalconductivity and 6000 mg/l as a dry residue. In order to study the tolerance for the salt, twovarieties of barley were used: Ardhaoui (local variety) and Pakistani (variety introduced fromPakistan). During the experiment, monitoring of water and soil characteristics was realized.
Measurements have focused on physical and chemical analysis of soil and irrigation watertaking into consideration the irrigation mode: drip irrigation, improved flooding irrigation,flooding irrigation and spraying irrigation.
The results indicate that the salinity for the plots irrigated by brackish water, increase on thesurface for all treatments especially during dry season, except those irrigation by the drip
system where the surface salinity is relatively low. The electrical conductivity in the soil iscorrelated with the content of the Sodium and the chloride. The sulphate levels are also highmainly in the deep layers. However, during the dry season, the sulphates are carried bycapillary to surface layer. This experiment indicates also that the two varieties of barley(Ardhaoui and Pakistani) have great capacity for resistance to water and soil salinity, especiallyfor flooding improved technique.

Keywords: Arid climate, Barley, Brackish water, Irrigation techniques, Soil salinity
1. Introduction
The phenomenon of soil salinity is a major obstacle to improve yields in arid areas, especially whenwater resources are limited and generally of poor quality. Indeed, the lack of rainfall and high evaporation
makes intense use of irrigation required which leads to the extension and amplification of this phenomenon.
So many research activities have been undertaken to overcome these problems through the development oftechniques to reduce soil salinity and the identification of tolerant species to salinity. Thus, our objectives are:
- To study the effect of irrigation with brackish water in soil in arid zones.
- To identify the impact of irrigation on soil salinity and crops yields.
- To study the resistance of some crops to soil and water salinity: Barley (varieties Ardhaoui andPakistani).
2. Materials and Methods:
2.1. Location of the study area
The perimeter of El FJE is located 22 km north-eastern of Medenine (Tunisia). It covers an area of
174 ha and it is limited on the north by the Institute of Arid Regions (IRA) which is part of the perimeter,
by wadi El FJE on the south and by private farms on the east.
2.2. Experimental trials
This experiment (Fig. 1) was conducted at the Training Center and Agricultural Development of El
FJE Medenine in which a barley crop has been installed. After levelling, the experimental plot was divided
into four parcels. In each one, four irrigation systems (improved flooding, drip irrigation, flooding andspraying) were used to irrigate the two varieties of barley (Ardhaoui and Pakistani).

12

Laboratory of Eremology and Combating of Desertification, Institute of Arid Regions, Medenine
Soil Laboratory, Faculty of Sciences El Manar II, University Campus. Tunisia

336

A
A
A
A

A
A
A
A

PPP
P

Improved
FloodingPPPP

A
A
A
A

A
A
A
A

PPPPDripPPPPA
A
A
A

A
A
A
A

PPPPPPPPAAAAAA
A
A

P
PPPP
Pakistani Barley
AArdhaoui Barley

PPPPFlooding

SprayFig. 1. Experimental plot of Barley.

2.3. Sampling of water and soil
The soil study concerned the morph structural description of soil profile and a chemical analysis
laboratory of samples of each soil layer. In addition, soil samples were collected each month by auger
according to different depths (25, 50 and 75 cm); and were the subject of a laboratory analysis which
concerned: pH (pH-meter), EC (conductivity-meter), the ionic balance (Na+: spectralphotometer flameemission, SO42-: UV absorption spectralphotometer) of soil solution, the rate of gypsum (turbid metricmethod), limestone (volumetric dosing) and total organic matter (organic carbon dosing).
Water samples were also collected and analysed: pH, EC, the total dissolved salts (Afnor method) andionic balance (K+: spectralphotometer flame emission, Ca2+ and Mg2+: atomic absorption spectrometry).
These physical and chemical analysis of water and soil were conducted in the soil laboratory of theInstitute of Arid Regions (IRA) Medenine.
2.4. Statistical analysisThe general linear model of SAS software was used.
3. Results and Discussion:
3.1. Soil Study
It is a sandy soil (USDA, 1957) with low content inorganic matter (Table 1), its EC increases with the depth(from 5 dS/m in the surface layer to 8 dS/m in depth).
This may be explained by an increase of the gypsum
concentration with the depth (the Mio-Pliocene: clay andgypsum constitute the bed rock of the soil).

Depth(cm)EC (dS/m)

Ca CO 3
Total (%)

Gypsum(%)

Organicmater (%)

pH0-15 cm

5.32

5.55

0.370.92

7.1115-25 cm

7.99

8.33

1.50.18

7.2325-45 cm

8.57

8.33

3.45

0.07

7.15

60

60

50

50

40
[ ] méq/l40[ ] meq/l

3.2. Irrigation water
The chemical analysis of irrigation water shows atotal dissolved salts ranging between 5.2 and 6.05
g/l and an electrical conductivity ranging from 7 to8 dS/m according to the seasons and theexploitation rate of ground water. Irrigation watersalinity (USLS, 1954) is high, with sulphate
sodium chloride facies and high alkaline risk.

Table1. Soil characteristics.

3030202010100h1( 0-15cm)

h2 (15-25cm)

h3 (25-45cm)

0h1( 0-15cm)

Na+h2 (15-25cm)
ho ri zo ns ( cm)K+

h3 (25-45cm)

Ca++Mg++Cations concentration in irrigationwaterhorizons (cm)SO4--

HCO3--Cl-

Anions concentration in irrigationwaterFig. 2. Ionic balance of irrigation water.

3.3. Impact of irrigation water on soil electric
conductivity and Sodium content
The irrigation system has an effect on salinity and crop yields, in terms of quantity and quality. For
this reason, comparing the effect of irrigation on soil salinity is important to preserve our resources in theground against the degradation mainly by salinisation.
According to the vertical variation of soil salinity as a function of time (Fig. 3), we note that before
sowing (December 2006), the salinity profile was homogeneous for different treatments with a significant
increase for the layer 25 cm attributed to low rainfall (Precipitation = 1.4 mm). Also, an increase in the salt
concentration on the surface was identified for all treatments in January 2007 due to an important3371015EC dS/m
4628100005050

AprMayMay75

4060

800[Na+] méq/l2040252550

depth (cm)depth (cm)Mardepth (cm)

0Mar505075

100MayFlooding[Na+] meq/l

125

150

050

100

150

2000Dec

25JanMarDec
25JanMar50

AprAprMay75

Improved Flooding

25AprMay
75

Apr75

50

Apr35

Mar[Na+] meq/l
60Jan30MayDec

Jan

25500Dec

20

Apr

75

015JanDrip
SprayFig. 3. Vertical variation of salinity as a function of time.

010DecMardepth (cm)20525Jan5075[Na+] meq/l00025Mar

AprImproved Flooding

25Dec

Jandepth (cm)depth (cm)

MarEC dS/m

20Dec
25

JanEC dS/m
10150Dec255depth (cm)

50depth (cm)0EC dS/m

MayMay75

75

Drip
SprayFig. 4. Vertical variation of sodium in the soil.

Flooding

rising during this month because of the high temperature and the lack of rainfall. Indeed, for the drip
irrigation system, the EC has not exceeded 10 dS/m, while for all other irrigation system, a highconcentration of salts was recorded at the surface: it exceeded 20 dS/m for the improved flooding
irrigation system and the spraying irrigation system and more than 31dS/m for flooding irrigation system.
Thus, the drip irrigation system helps to maintain soil salinity to levels relatively low compared with othersystems, especially during dry periods.
Since irrigation water has a sulphate sodium chloride facies, the sodium (Fig. 4) and chloride
variation follows exactly the changes in the EC and has therefore confirmed our results on the salinity ofthe soil. These experimental results are confirmed by a statistical analysis (Table 2) of variance and acomparison of averages using the general linear models of SAS software.
3.4. Vertical Variation of sulphates in the soil as a function of time
The sulphate concentration in the soil (Fig. 5) depends mainly on two factors time and depth. It
appears that the effect of the irrigation system is hidden by other factors: gypsum content among others.
The sulphate levels are high in depth because the soil bedrock is the miopliocene with a high concentration
Table 2. Comparing averages for EC and Na variables for factors time, depth and irrigation system.
Modality

Time (months)

Depth (cm)Irrigation System

January
MarchApril
May
0255075
Improved Flooding
DripSprayFlooding

EC (dS/m)
Averages*10.77
A
5.36
B
4.58
B
4.40
B
9.52
A
6.51
B
5.99
B
5.40
B
5.90
A
5.70
A
7.90
B
8.02
B

Na (meq/l)Averages
*
57.51
A
24.24
B
22.90
B
20.05
B
52.94
A
31.37
B
28.66
B
26.04
B
30.14
A
27.80
A
40.30
B
40.55
B

*The averages with the same letter are not statistically different

338

of gypsum. However, in dry period (January and May), the sulphates are carried by a capillarity rising tothe soil surface.
--020[SO4 ] me q/l4060[SO4--] meq/l80

00153045

--

60075

[SO4 ] meq/l2550--[SO4 ] meq/l75

000

Dec

204060800Dec50Aprdepthr (cm)

25

Mar50

25

Mar50

AprJanMar50
AprMayMay75

Improved Flooding

25

AprMay75Jandepth (cm)MarDecJan

depth (cm)Jan

depth (cm)

Dec
2575

Drip
SprayFig. 5. Vertical Variation of sulphates in the soil.

May75Flooding

3.5. Effect of irrigation water on barley yield

The effect of irrigation on the yield of barley is variable. We note that the technique of spray
irrigation allows for good water management but it is subject of some criticism (Slama, 2004) (including
burning and early senescence of leaves).
- The drip irrigation although it allows for saving water, it can lead to spatial heterogeneity of salinity andpoor leaching salts.
- For flooding irrigation does not save water particularly in arid areas where water is precious and rare.
Thus, the flooding improved irrigation could giving the best crop yield.
It should be noted that the production of two varieties of barley (Ardhaoui and Pakistan) was low for
all treatments (because of birds). However, depending on the status and vigour of plants, there is nodifference between the two varieties concerning their resistance to soil and water salinity.
4. Conclusions
The soil salinity variation during irrigation by saline water is high on the surface for the different
treatments especially during dry period except for the drip irrigation system where the surface salinity isrelatively low.
The EC in the soil is well correlated with sodium and chloride. The sulphate levels are high in depth.
However, during the dry period, the sulphates are carried by a capillarity rising to the soil surface. The twovarieties of barley (Ardhaoui and Pakistani) have great capacity for resistance to water and soil salinity
especially for improved flooding irrigation system.
References:
Slama F. (2004): Salinity and crop production. Academic Center Publication. Tunis: 161p.
U.S.LABORATORY STAFF (1954): Diagnosis and Improvement of saline and alkali soils. US. Dept. Agric. Hanbd., n°60,
Washington Vol. II, 160p.
USDA (1975): Keys of soil Taxonomy, Corney. University. USA