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Sustainability of irrigated agriculture under salinity pressure – A study in semiarid Tunisia

Bouksila, Fethi LU (2011)
Abstract
In semiarid and arid Tunisia, water quality and agricultural practices are the major contributing factors to the

degradation of soil resources threatening the sustainability of irrigation systems and agricultural productivity.

Nowadays, about 50% of the total irrigated areas in Tunisia are considered at high risk for salinization.

The aim of this thesis was to study soil management and salinity relationships in order to assure sustainable

irrigated agriculture in areas under salinity pressure. To prevent further soil degradation, farmers and rural

development officers need guidance and better tools for the measurement, prediction, and monitoring of soil salinity at

different observation... (More)
In semiarid and arid Tunisia, water quality and agricultural practices are the major contributing factors to the

degradation of soil resources threatening the sustainability of irrigation systems and agricultural productivity.

Nowadays, about 50% of the total irrigated areas in Tunisia are considered at high risk for salinization.

The aim of this thesis was to study soil management and salinity relationships in order to assure sustainable

irrigated agriculture in areas under salinity pressure. To prevent further soil degradation, farmers and rural

development officers need guidance and better tools for the measurement, prediction, and monitoring of soil salinity at

different observation scales, and associated agronomical strategy. Field experiments were performed in semi-arid

Nabeul (sandy soil), semi-arid Kalâat Landalous (clay soil), and the desertic Fatnassa oasis (gypsiferous soil). The

longest observation period represented 17 years. Besides field studies, laboratory experiments were used to develop

accurate soil salinity measurements and prediction techniques.

In saline gypsiferous soil, the WET sensor can give similar accuracy of soil salinity as the TDR if calibrated values

of the soil parameters are used instead of standard values. At the Fatnassa oasis scale, the predicted values of ECe and

depth of shallow groundwater Dgw using electromagnetic induction EM-38 were found to be in agreement with

observed values with acceptable accuracy. At Kalâat Landalous (1400 ha), the applicability of artificial neural network

(ANN) models for predicting the spatial soil salinity (ECe) was found to be better than multivariate linear regression

(MLR) models. In semi-arid and desertic Tunisia, irrigation and drainage reduce soil salinity and dilute the shallow

groundwater. However, the ECgw has a larger impact than soil salinity variation on salt balance. Based on the findings

related to variation in the spatial and temporal soil and groundwater properties, soil salinization factors were identified

and the level of soil “salinization risk unit” (SRU) was developed. The groundwater properties, especially the Dgw,

could be considered as the main cause of soil salinization risk in arid Tunisia. However, under an efficient drainage

network and water management, the soil salinization could be considered as a reversible process. The SRU mapping

can be used by both land planners and farmers to make appropriate decisions related to crop production and soil and

water management. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Aragues, Ramon, AGRIFOOD RESEARCH AND TECHNOLOGICAL CENTER OF ARAGON
organization
publishing date
type
Thesis
publication status
published
subject
defense location
V:B
defense date
2011-11-25 13:00
language
English
LU publication?
yes
id
06ecb191-5980-4260-886f-48072a3f2b01 (old id 2199581)
date added to LUP
2011-11-01 09:52:06
date last changed
2016-09-19 08:45:17
@phdthesis{06ecb191-5980-4260-886f-48072a3f2b01,
  abstract     = {In semiarid and arid Tunisia, water quality and agricultural practices are the major contributing factors to the<br/><br>
degradation of soil resources threatening the sustainability of irrigation systems and agricultural productivity.<br/><br>
Nowadays, about 50% of the total irrigated areas in Tunisia are considered at high risk for salinization.<br/><br>
The aim of this thesis was to study soil management and salinity relationships in order to assure sustainable<br/><br>
irrigated agriculture in areas under salinity pressure. To prevent further soil degradation, farmers and rural<br/><br>
development officers need guidance and better tools for the measurement, prediction, and monitoring of soil salinity at<br/><br>
different observation scales, and associated agronomical strategy. Field experiments were performed in semi-arid<br/><br>
Nabeul (sandy soil), semi-arid Kalâat Landalous (clay soil), and the desertic Fatnassa oasis (gypsiferous soil). The<br/><br>
longest observation period represented 17 years. Besides field studies, laboratory experiments were used to develop<br/><br>
accurate soil salinity measurements and prediction techniques.<br/><br>
In saline gypsiferous soil, the WET sensor can give similar accuracy of soil salinity as the TDR if calibrated values<br/><br>
of the soil parameters are used instead of standard values. At the Fatnassa oasis scale, the predicted values of ECe and<br/><br>
depth of shallow groundwater Dgw using electromagnetic induction EM-38 were found to be in agreement with<br/><br>
observed values with acceptable accuracy. At Kalâat Landalous (1400 ha), the applicability of artificial neural network<br/><br>
(ANN) models for predicting the spatial soil salinity (ECe) was found to be better than multivariate linear regression<br/><br>
(MLR) models. In semi-arid and desertic Tunisia, irrigation and drainage reduce soil salinity and dilute the shallow<br/><br>
groundwater. However, the ECgw has a larger impact than soil salinity variation on salt balance. Based on the findings<br/><br>
related to variation in the spatial and temporal soil and groundwater properties, soil salinization factors were identified<br/><br>
and the level of soil “salinization risk unit” (SRU) was developed. The groundwater properties, especially the Dgw,<br/><br>
could be considered as the main cause of soil salinization risk in arid Tunisia. However, under an efficient drainage<br/><br>
network and water management, the soil salinization could be considered as a reversible process. The SRU mapping<br/><br>
can be used by both land planners and farmers to make appropriate decisions related to crop production and soil and<br/><br>
water management.},
  author       = {Bouksila, Fethi},
  language     = {eng},
  school       = {Lund University},
  title        = {Sustainability of irrigated agriculture under salinity pressure – A study in semiarid Tunisia},
  year         = {2011},
}