Tunisia
This report was compiled by
Dr. Amor Mtimet, Ministry of Agriculture - Direction des Sols
Last updated: 29 July 2004
News :
Directory of Soil Institutions and Experts in Africa is available through [Link 2.2.1].[29/07/04]
Overview [Geography|Socio-economy|Climate]
Land resources
Water resources (AQUASTAT)
Plant nutrient resources
Hot spots
Bright spots
Challenges and viewpoints
References / Related internet links
Facts
[Outline
map of Tunisia - http://www.graphicmaps.com]
1.1 > 1.
Population
Economy and agriculture
Agricultural production
[Table
1.2.1: Economic incomes, 1993]
Agriculture in Tunisia occupies an essential place in the development strategy because of its social and strategic dimensions. It has a much greater role than the other economic sectors owing to its extreme importance in realizing the balanced development and developing the interior areas, as well as ensuring food security, which is one of the essential conditions of the national sovereignty. The importance of the agricultural sector appears through many indices, of which the most important ones are its mean contribution by 16% to the total national product and 10% to the national exportations in the last years, knowing that these rates reached higher values in the years in which the weather was suitable. The agricultural sector also contributes by 22% to the employement and gets 16% of the investments, besides the supplying, totally on partially, of an in come to 471 thousands farmers and 60 000 fishermen.
[Map
1.2.1: Agro-economic regions]
[Table
1.2.2: Agriculture in relation to land use]
Food-grains
Cultivation of cereals one of the main agricultural activities, at the same time is terms of the area used annually, which covers 1.6 millions ha and represents more than two-thirds of the cultivated area; and in terms of the number, of cereal growers, which is 240 000, that is 51% of all the farmers in the country. At present, the mean production of food grains is 1,45 millions tons per year, of which one million tons of hard wheat.
The production of cereals contributes by 16% to the total agricultural product, and ensures almost all our consumer needs in hard wheat and barly of the country.
A special plan was elaborated to better develops this domain in order to produce a mean of 2,5 millions tons per year 2006.
Fruit-trees
Fruit-trees cover about 2 millions ha ( 40% of the cultivated soils ), of which 1,3 millions ha of olive-trees, 300 000 ha of olive-trees mixed with other fruit-trees ( especially almond-trees ), 170 000 ha of almond-trees, 29000 ha of date -palms and 15000 ha of citrus-fruit trees.
Arboriculture is one the most important activities in the country, since it contribute by 28% to the agriculture production and ensure all our consumer needs and a pert of the exportations, representing 60% of the exported food products.
Breeding
The livestock is estimated at 723000 unity of cattle, 7.78 millions of sheeps and goats and about 70 000 camels.
And the number of breeder is 335000. Which represents more than 71% of the total number of farmers in the country.
The sector of breeding is among the most important agricultural activities, since it contributes by 35% in the overall agricultural production and ensures the major part of our needs in meats and milks. The mean production in the last years reached 177 500 tons of meat ( of which 90000 tons of read meats ) and 534 000 tons of milk.
Vegetables
Vegetables cover on the average 140 000 ha per year ( 110 000 ha irrigated and 30000 ha rainfed) 22 000 ha of tomate, 16.000 of potato, 17.000 ha of pepper and 34000 ha of melon and water-melon. This sector represents 15% of the agricultural production.
1.2 > 1.
Mediterranean on the north and along side the costs, semi-arid and aride inside and on the south.
[Map
1.3.1: Mean Annual Temperatures in Tunisia]
[Map
1.3.2: Bio-climatic map]
[Map
1.3.3: Rainfall in mm]
[Photo
1.3.1: Agro-climates and soils]
[Photo
1.3.2: The arid domain]
Also refer to [Section 2.3: Agroecological systems]
1.3 > 1.
2.1 Physiography
2.2 Soils
2.4 Wetlands, mangroves and inland valley bottoms
2.5 Inundation Land Types
2.6 Natural hazards
2.7 Land cover
2.8 Land use
2.9 Land use change
2.10 Land Productivity
2.11 Environmental Impact of land uses
2. > top
There are 9 physiographic units (Mtimet, 1999).
[Map
2.1.1: Geologic map]
2.1 > 2.
[Link
2.2.1: Directory of Soil Institutions and Experts in Africa]
Soil and agricultural land
Characteristics of gypseous soils in the oasis
General use of land based on soils
[Map
2.2.1: Soil map of Tunisia]
[Map
2.2.2: Synthesis soil map]
[Table
2.2.1: Regional distribution of soils]
[Table
2.2.2: Major soil units and potentials of arable land]
[Table
2.2.3: Regional distribution of soils - systhesis]
As for water resources the climatic distribution of Tunisia influences the use and productivity of soil resources of the country. Lands suitable to cultivation cover about 5 millions hectares, of which 57% are in the center, 11% in the south and 31% in the North, Forests and rangelands extend over a total area of 5,5 millions ha, of which about 60% are in the south, 23% in the center and 17% in the north.
The area of high-fertility soils does not exeed 3 millions ha, of which 500 thousands ha are suitable for irrigation; of this latter area only 350000 ha are being used at present, that is 7% of all the area suited to be cultivated.
The major part of the agricultural lands, forests and rangelands are situated on slopes, which reduces their fertility and increases its sensitivity to erosion. Because lands in Tunisia have been used since the ancient times, ( about three thoushands years ) and the continuous cultivation of less fertile lands even under the difficult climatic conditions, lands subject to water erosion increased, reaching 3 millions ha, of which 71% in the northern zones and Cap Bon, and 22,7% in the high lands. As regards land subject to desertification, located mainly in the south, 50 % of these lands are seriously or mederately affected by this from of degradation.
Refer to [Section 2.6: Land use] for more information on soils and land use.
Characteristics of gypseous soils in the oasis
Their textures are composed of fine sand and some times of silt. Salt ( soluble and moderately soluble ) are sodic and gyseous , with an accumulation of the latter at the bottom of the soil, resulting in the formation of gypseous crusts, which are very related to ground waters. As regards the characteristic value of the moisture content, the milting point and the 0.5 bar water percentage are, respectively, 9% and 20%.This shows that leaching of salts is easy in these soils by applying farmer classic methods used in this case ( submersion irrigation ).The gypseous crust in these soils is the major constraint to their intense agricultural use, what are its characteristics and composition?
The gypseous crust, which may be found at the surface or the bottom of the soil ( 60 - 120 cm ) and have different thickresses ( 10- 60 cm ) , is related to the anciant environment and changes as a result of agricultural exploitation and other managements.
The main typses of this crust are as follows:
General use of land based on soils
The study of the arid and sub-desert areas ( ¾ of the total area of the country ), based on a survey of the soil resources, shows that these areas have soils composed mainly of fine and coarse sands with a calcareous and gypseous crusts. Because of the aridity, which limits the evolution of the soil, these areas are, in most cases used as rangelands.
These rangelands are undergoing a high pressure from men and animals. And, owing to its fragile and sparse vegetation cover, subjected to a continous decrease due to cultivation in rainy years and overgrazing, the soils are affected by erosion, and thus loose their fertility and the components of their durability. This of couse leads to desertification and degradation of the environmental systems of the arid areas in Tunisia.
When the soil is more tick ( deep crust, or a beginning of a gypseous crusting ), percolation of irrigation water is almost inexistent in spite of the high soil permeability. The low organic matter content and the gypsous and sandy texture means that these soils have low water retention capacity. And because these soils are situated in most cases, in areas neighboring wadis and depressions (Chott of Jerid ), they become more and more hydromorphic and saline as a result of a bad drainage. The oasis, which cover about 24000 hectares, represents approximately 10% of the whole area of southern Tunisia. The water resources of this part of the country are essentially undergroud and over-exploited, and its soils are characterized by accumulations of wadi sediments and wind sands. The main crops in the oasis are date-trees, fruit trees and market gardenings and some industrial crops such as the henna and tobacco.
2.2 > 2.
Natural resources of Tunisia are characterized by their sensitivity to degradation when they are not managed rationally. But this sensitivity varies according to the nature of the resources and the regional climate. The latter, indeed, varies from the subhumid in the extreme north to the arid in the south. Rains are irrigular and dry periods are more frequent in the center and South. All these climatic characteristics influence the type and sensitivity of the natural resources. Tunisian, the area of which is 16.4 millions hectares, has 4.5 millions hectares of agricultural lands, 3,5 millions hectares of agricultural lands, 3,5 millions hectares of which are effectively fertile. Distributed into thee great natural regions, the agro-ecological areas have distinct gricultural specificities :
The major part of these areas are dependent on the climatics conditions.
The agricultural policies in the last years ( investments and encouragements ) have favoured the intensification of the traditional agriculture and the development of irrigated areas ( creation, extension, reclamation ), with a diversification of crops and the increase of the production. The total area suitable for irrigation is about 400 000 hectares, with an orientation towards large scale crops, arboriculture and vegetable farming.
Mechanization and use of organic and mineral enriching agents have enabled the extension of cultivated lands and the speed of this evolution. The best yields, however, remain dependent on diverse factors and the knowledge of the environment.
The South West comprises the large desert expanses of Chott Jerid, Chott Rharsa and the Erg. The only cultivated lands confine themselves in the traditional ( Nefsaoua, Jerid, Gafsa) or the modern ( new irrigated areas : Ibn Chabbat, Hazoua, Regim Maatoug and Faouar ) oasis. The rest of the space constitute the rangelands for the nomads around the Chotts and near the Dahar.
The South East : fruit arboriculture ( olive- trees, fig-trees, almond trees ) dominate in the plain of Jeffara, which receives run off waters. The littoral Oasis of Gabès, Medenine and Jerba are situated on alluvial terrains and irrigated from deep drillings with high salinity waters ( > 3g/l ). Occasional cereal crops and irrigated areas ( Sidi Maklouf, Ben Gardane ) are scattered in the region. The saline terrains of rangelands are localised alongside the salt lakes ( El-Melah, El-Adibet ….) and in the plain of El Ouara.
2.3 > 2.
Sea resources
As regards the natural resources in the marine environments, extending over the 7 millions ha of our territorial waters, they include about thousands tons of blue fishes, besides large quantities of other fish types, which are being identified and the reconstitution of their stocks being estimated.
2.4 > 2.
Information currently not available
2.5 > 2.
Information currently not available
2.6 > 2.
Forest
Forests represents the most suitable environment for the conservation of biological diversity in Tunisia, there fore 24 reserves were created representing samples of the different environmental systems in the country and covering a total area of about 80 thousands ha ( without counting the reserve of Jebil in the south ) which represents about 10% of the forest areas.
It should be noted that forests and bushs cover about 900 000 ha, of which approximately 780 000 ha in the north, and that the Tunisian forest systems are characterized by the diversity of their types and its adaptation to the variation to the variation of the climate.
Refer also to Section 2.8: Land use.
2.7 > 2.
Division of land according to bioclimates and vocation
[Table
2.8.1: Division of land according to bioclimates and vocation]
Land use types
[Table
2.8.2: Land use types]
[Map
2.8.1: Land use and land use distribution]
A. The forest lands of the North and Center
B. The cereal lands
C. Arboricultural lands
A. The forest lands of the North and Center
The forest lands of the North and Center cover 675000 ha of forests composed of cork oaks, holm-oaks, pines…They stretch out on the mountains of Kroumirie, High tell and Tunisian Dorsale : mountains, hills, glacis with mediterranean brown soils, calcareous soils and rendzina.
According to bioclimate and sensisitivity the different types of land may be classified as follows:
- the cereal lands in the North and North-West;
- the arboricultural land in all Tunisia;
- the irrigated lands of the low plains and oasis in the south;
- the forest lands in the North and Center;
- the rangelands in the Center and South;
These lands are mainly formed by vertic soils or isohumic soils ( brown or red - brown )
Two constraints of physical nature have to be overcomed in order to exploit these soils. The first one is the slope, when this factor is greater than 8% in marly terrains, intensive mechanization causes landslides and gullying. So, marshs may form, in which hydromorphic phenomena are spectacular. Such zones are clearly distinguishade in the regions of Jendouba and Kef. Besides, monitoring of water and nutritional reserves is also very important.
They comprise deep brown soils and medium - textured alluvial soils, distributed among all the bioclimatic zones.
These soils are threatened when there is :
- a slight thickness ( < 80cm )
- a small slope
- a fine texture ( clayey to clayey and silty )
- a gypseous crust not far from the surface ( < 40 cm)
Arboricultural soils have to be protected from runoff by different land conservation works ( teraces, cordons,….) and thus benefit, in central and southern Tunisia, from a supplement of water during rainy periods. They represent more than 2/3 of the cultivated lands (3.5 millions ha ). The olive tree, by itself, occupies 1.5 millions ha of the Tunisian territory.
2.8 > 2.
Changes of land area in relation to population
[Table
2.9.1: Changes of land area in relation to population]
2.9 > 2.
[Table
2.10.1: Estimation of areas of land suitable for cereals production]
[Table
2.10.2: Land suitability for rainfed cultivation of trees]
2.10 > 2.
Information currently not available
2.11 > 2.
Tunisia country profile on AQUASTAT (choose from the list).
The total volume of water resources is about 4.7 billions m3 : 2,7 billions m3 of surface waters, 80% of which are in the north; and 1.998 billions m3 of ground and underground water, of which, 80% are situated in the water resources are used, that is approximately 2.6 billions m3 of water per year, mainly used for irrigation.
Even that the mean uses do not exeed 57% of the reserves, rational management of the natural resources requires the protection of water sources, rationalization of their use and the mobilization of water resources.
3.1 > 3.
Irrigated lands
Methodology of the study
The irrigated surface areas are continually increasing in our country as advance the programs of mobilization of run off and ground waters, so much so that they have presently reached about 370000 ha, and, according to the predictions of the next five year development plans, theses surfaces must rise to 400 000 ha. These important realizations, which contribute to intensify land productivity and increase agricultural production of the country, constitue precious acquisitions which should be safeguarded and exploited as long as it is possible.
Secondary salinisation of soils is one of the factors causing the fall of the land productivity in the irrigated areas; its origins are multiple and diverse and the prevention from this process requires essentially appropriate management of soils and irrigation waters. The programs for the control of the evaluation of secondary soil salinisation in the irrigated perimeters, established as permanent activities in the Direction of Soils, aim at localizing salinized areas, determining the origins of salinisation and its position in the profile, and setting out suggestions for improving and reclaiming soils.
In Tunisia, the total surface suitable for irrigation is about 400000 ha, 32% of which are in the North East, 31% in the Center - West, 22% in the North- West, 9% in the south and 6% in the Center East . Vegetable farming, large scale crops ( cereals, farming industry, fodder crops and leguminous plants ) and fruit arboriculture stretch out from to year around dams and drillings. This extension is greater in the Center west and the South in comparaison with the other regions.
It is in the Center and the South where high - salinity waters are used to irrigate fine - textured soils ( silty to silty clay ) that, we have to take great care of the management of irrigation and drainage.
The phenomenon of salinisation appear during the periods of dryness, decrease in the outfollow of drillings as well as intense irrigation, which results in the rising of the level of ground water : low plains of Medjerda and Kairouan, periphery of salt depressions and lakes, where drainage is nearly inexistent.
3.1 > 3.
4.1 Plant nutrient use and nutrient balance
4.2 Fertilizer production and costs
4. > top
Information currently not available
4.1 > 4.
Information currently not available
4.2 > 4.
5.0 Overview: constraints to sustainable agriculture
5.3 Plant nutrition-related constraints
5.4 other constraints
5. > top
The Process of degradation
New studies have shown the absence of important climatic changes since the end of the last century and therefore the present causes of desertification cannot be attributed to the dryness of the climate ( Floret et Pontanier, 1982, Floret et al, 1989). These are limited rather to human and animal pressure on fragile environments. This pressure can express itself in the following actions and effects :
- inadequate use of soil, which consists in the extension of arboriculture and cereal crops in zones that can be used only as rangelands;
- use of inadequate equipment for the preparation of soils ( for example the use of polydisc plow in sandy soils sensitive to wind erosion ); ( IRA, 1989)
- the increase of livestock and reduction of rangelands, which entails excessive overgrazing leading to a deterioration of soils and a reduction of plant species suitable for grazing;
- removal of wood for domestic needs. Which is one of the main causes of the extinction of arborescent species and shrubs,
- use of high salinity water for irrigation contributing to the salinisation of soils and the drop or even the loss of their fertility ( Mtimet, 1985; Mtimet, Hachicha, 1995).
5.0 > 5.
Aptitudes and constraints of soils with respect to agricultural development
Water erosion
Wind erosion
Deterioration of vegetation cover
Deterioration by hydromorphy and salinisation
The effect of urbanization
Aptitudes and constraints of soils with respect to agricultural development
The Tunisian soils are subject to very strongly contrasting climatic factors : dryness ( ¾ of the surface area of the country ), torrential short rains; and to more and more important anthropic factors next to the littoral ( urbanization, insuitable farming practices, land problems ). In order to summarize the main soil degradation processes, we shall examine the importance of the following factors :
- water erosion,
- wind erosion,
- urbanization,
- salinisation and hydromorphy
These processes affect on average about 23000 ha, among which a large part, about 10000 ha, is subject to water erosion.
The present water and soil conservation strategy consists, to a great extent, in reducing, or even doing away with the effect of these factors ( regions of kef, siliana and kairouan ).
The obstacles and factors taken ino account in the development are the slope, tickness, texture, permeability, calcareaous content, salinity and drainage .
At the national and regional scale; 29% of lands are occupied by agriculture, 36% by rangelands and 31% are unsuitable for cultivation. Fertile lands represent 21,5% of the whole surface area of the country (Mtimet et al, 2001).
[Map
5.1.1: Water and wind erosion]
[photo
5.1.1: Relation between water and arid soils]
This type if erosion causes the loss of the arable layer of soils, its intensity depends on the topography of the superficial layer, the nature and density of vegetation cover and the nature of precipitations (Bel aid, 1969). ( Bahri et al, 1989)
The annual loss of soil related to water erosion is about 49 millions m3, that is 10000 ha of useful agricultural soils ( Hentati et al, 1989).
Land exposed to water erosion is located mainly in the water-sheds of wadis of Mejerda, Mellègue, Tessa, Nebhana, Zeroud and El- Fekka, as well as in the mountains of Gafsa and Matmata . The total area affected by water erosion is estimated at 3.321.630 ha, that is, 20% of the whole surface area of the country( Mtimet et al, 1996).
- Loss of fertility in agricultural land is the reason for falling crop yields, leading to the clearing of further land in forests and rangeland.
- Tunisia has a hydrological infrastructure on which the economic development of the country now depends to a large extent : irrigated land, potable water, industry, tourism…This infrastructure is threatened by silting and premature filling in ( dams and pipelines ) and by the drop in the piezometric level of groundwater. Indeed, 25 millions m3of sediment is deposited each year in the dam reservoirs leading to a decrease in water available for irrigation and drinking.
- A large quantity of water, in the order of 500 millions m3, which is not withheld by dams is being lost in the Sebkhats and the sea, sometimes leading to salination of the plains.
- Insufficient soil and water conservation works in certain regions has prevented the achievement of agricultural development goals, indeed :
- Agricultural development in southern Tunisia cannot be achieved without S.W.C. works, in particular jessours.
- The conservation of olive groves in the Sahel depends, to a large extent, on the existence of Meskats.
- Spreading of flood water still constitutes a very efficient means of using runoff water in central Tunisia.
An increase in the risk of flooding and of consequent damage to infrastructure and settlements (Refer to [Table 6.1.1: Water and Soils conservation strategy]).
Silting up represent the last stage of soil deterioration, leading to desertification. More than two thirds of the country is subject to wind erosion. Contrary to what one would believe, maximum intensity is not in the extreme south, but in the region bound by the districts of Mahdia, Kairouan, Sidi Bouzid, Gafsa and Gabès, with the district of Sfax at its centre. In some parts of this region, the annual transportation of sand is estimated at 50 to 200 t/ ha. (IRA, 1989).
As regards the other regions exposed to wind erosion, which extend from Kairouan to the extreme south (Jefara and El Ouara ), the intensity of sand transportation is estimated between 10 and 50t/ ha/ an, and wind erosion damages 8.000 ha annually.
Deterioration of vegetation cover
The decrease in the vegetation cover may lead to a drop in soil fertility ( decrease in the organic matter ) and the deterioration their structure results in the loss of the superficial layers and outcropping of calcareous and gypseous crusts.
The forest cover has decreased considerably owing to the development of extensive agriculture ( arboriculture and food grains ) since the end of the last century. The same applies to land occupied by esparto, extending previously over more than one million ha and which, at present, occupy about 450000 ha. With regard to steppe rangelands degeneration is so serious, that it has led to a reduction in vegetation cover and an greater scarcity of plant species suitable for grazing (IRA, 1989).
Deterioration by hydromorphy and salinisation
Lands affected by salinization are estimated at 9.13% of the total surface area of the country. At the regional scale, soils affected by this phenomenon cover about 20% of the whole area of the presaharan Tunisia ( salt lakes and depressions etc. ).
The expansion of irrigated areas ( favoured by the exploitation of new water resources ) without drainage in hydromorphic zones and leaching in saline zones may lead to a sterilization of soils ( Guellali, 1980; Mtimet, 1990; M'hiri et al, 1998).
Other types of deterioration may be recalled :
- acidification, shown trough the fall of the saturation in exchangeable bases;
- Toxicity : represented by increase in toxic elements ( Na ) (FAO, 1980 in Mtimet, 1990);
- Physical deterioration : expressed by the increase in bulk density or the decrease in the permeability
The total of the area affected is 1000 ha / year.
This phenomenon, which has accelerated over the last years all over Tunisia and especially in the costal zones, encroaches on agricultural lands surrounding the ancient cities and towns; 4000 ha are, on average, devoured annually by anarchic urbanization (EC, 2000 ).
On the whole, the loss of soil is estimated at 23000 ha / year and sometimes among the most fertile lands.
5.1 > 5.
Refer to [Section 5.1: Land-related constraints - Water erosion].
5.2 > 5.
Information currently not available
5.3 > 5.
Information currently not available
5.4 > 5.
6.0 Overview: society's response to ameliorate the situation
6.1 Land-related response indicators
6.2 Water-related response indicators
6.3 Plant nutrition-related response indicators
6.4 Other response indicators
6. > top
International cooperation for sustaible agriculture
[Text
6.0.1: Coopération Tuniso-Italienne, Programme FAO de Conservation des Eaux
et du Sol en Tunisie (Word Doc. zipped - 506KB)]
[Text
6.0.2: Conservation des Eaux et du Sol en Tunisie - Juin 2002 (PDF 141kb)]
6.0 > 6.
Water and Soils conservation strategy
[Table
6.1.1: Water and Soils conservation strategy]
6.1 > 6.
Refer to [Section 6.1: Land-related response indicators - Water and Soils conservation strategy].
6.2 > 6.
Information currently not available
6.3 > 6.
Information currently not available
6.4 > 6.
For the future :
A GIS, as a geo-referenced data-base, becomes little by little the indispensable tool for the management and maintenance of development works. Well known and used for the last ten years, essentially by the big companies and institutions, progresses in software and hardware are so important that the tool becomes within the means of all the management levels of a specialised system, from the farm to the agricultural area. This democratisation of the tool is not only due to the important reduction of its cost, but also and especially to the fact that all data are classified within a structure organized in specialized and linked levels. The management of the development works, aiming at on optamized production, in improvement of the farming conditions, a preservation of the system, etc. requires necessarily this basic tool the GIS, which, by gathering together all the map documents concerning a zone, presents not only the environment, but also the monitoring points necessary for the rational functioning of this environment.
How, does a GIS become integrated as an aid tool for the management and prevision in the strategic orientations chosen by Tunisia in the sector of irrigated agriculture ? (SIRS, 2001) knowing that the three key words of water savings in Tunisia, faced with an imbalance between supply and demand in water, are :
- water resources integration;
- preservation of the resource and supervision of the environment;
- management of water demand.
7. > top
1- Ouvrages Généraux ( Direction des Sols )
2- Salinité ( Salinity )
3 - Fertilité ( Fertility )
4 - Agriculture
1- Ouvrages Généraux ( Direction des Sols )
[1] Braudeau E., 1995 - Caractérisation des propriétés hydro-structurales des sols dans les périmètres irrigués de Tunisie ( la rétractométrie ) ES 286 - Direction des Sols.
[2] Boutiti R. 1994. Utilisation des eaux salées en agriculture. Les actes des premières journaux scientifiques du CRGR 58-63. Nabeul 27-28 Septembre 1994.
[3] Bulletin des sols N° 15, n°16 - 1994 - 1996 - Direction des Sols - Ministère de l'Agriculture
[4] Cruesi - Tunisie / PNUD 6 UNESCO. 1970. Recherche et formation en matière d'irrigation avec des eaux salées, 1962-1960. Rapport technique, 2143 p + cartes.
[5] Floret Ch., Et Pontanier R. 1982 - L'aridité en Tunisie présaharienne - série document - ORSTOM.
[6] Floret C., Mtimet A., Pontanier R ., 1989 - Caractérisation écologique des régimes hydriques et de l'érodibilité des sols en zones aride ORSTOM, Tunis, CEPE/CNRS , Montpellier, 44p. multigr.
[7] Freytag J., Mtimet A., 1994 - Soil carbon in the arid and semi arid tropics - colloque international sur l'emploi des techniques nucléaires I.A.E.A. - Vienne.
[8] Guellali T., 1980 - Transfert sels - matière organique en zones arides méditerranéennes. Thèse doc, d'Etat Université, Nancy 202 p.
[9] Hachicha M. et Ben Hassine H., 1990 - Irrigation et salure dans le périmètre de Zelba. ES 263 - Direction des Sols.
[10] Hamdane A. 1991 - Histoire et technologie des systèmes d'aménagement hydro-agricole traditionnel en Tunisie.
[11] Mhiri A., Tarhouni J., Hachicha M., et Lebdi F. 1998 - Approche systémique des risques de salinisation par endoréisation anthropique - étude et gestion des sols 5,4,1988 - pp 257 - 268.
[12] Mtimet A., 1987. Sauvegarde des oasis de la salure du Gouvernorat de Gabès ( état de la salure du sol et comportements hydriques - Février - Mars 1987) ES 241, ES 241, Direction des Sols, Tunis, 118p., annexes, 8 cartes h.t.
[13] Mtimet A., Hachicha M., 1995 - Salinisation et hydromorphie dans les oasis tunisiennes - Sécheresse n° 4 volume 6.
[1] Arvieu ( J.C. ), 1974. Les processus chimiques de l'évolution des phosphates en sols calcaires. Science du Sol, n° 4, 1974, p. 207 - 217.
[2] Ben Hassine ( H.), Aloui (H.) et Amdoouni (M.), 1998. Evolution mensuelle des réserves en azote minéral dans deux types de sols céréaliers, sous climat sub-humide du Nord-Ouest de la Tunisie. Campagnes agricoles 96-97 et 97-98.Document non publié, Direction des Sols, Ministère des Sols, Ministère de l'Agriculture.
[3] Ben Hassine (H.), Gasmi (M.), Marzouki (M.) et Younisi ( A.), 1999. Etude de l'évolution mensuelle des réserves hydriques et de l'azote minéral dans deux types de sols céréaliers de la région du Kef. Résultats des campagnes agricoles 96-97 et 97 -98. ES 308, Direction des Sols, Ministère de l'Agriculture.
[4] Ben Khelil (M.k.), 1989. Techniques de préparation du sol en grandes cultures. Bulletion « Sols de Tunisie « n° 13, Direction des Sols, Ministère de l'Agriculture.
[5] Giroux (M.), Lemieux (M. ), 2000. Effets de la fertilisation N, Pet K et leurs interactions sur le rendement d'une prairie à dominance de mil ( Phleum pratense L. ), la teneur en éléments nutritifs de la récolte et l'évolution de la fertilité des sols. Bulletin « agrosol « . IRDA, Sainte- Foy, Quebec, Canada.
[6] Hamrouni H., Mtimet A., Morel C., et Moutonnet P., 2001 - Acquisition de valeurs de référence pour raisonner la fertilité phosphatée de deux sols calcaire de Tunisie Centrale cultivés en blé ( à paraître ).
[7] Khalfallah (S.), 1989. Evaluation du potentiel de production des sols à céréals du Nord de la Tunisie. Bulletin « Sols de Tunisie « N° 13, Direction des Sols, Ministère de l'Agriculture.
[8] Projet AIEA1997 -2000 Séminaire de fin de projet - Kairouan - 2-3- /11/2000.
[9] Zaier (M.), 1988. Appréciation de la fertilité phospho-potassique du sol : problématique et normes d'interprétation. ES 247, Direction des Sols, Ministère de l'Agriculture.
[10] Zaier (M. ), Guesmi (M.), Brinis ( A.) et Marzougui (M.), 1996. Etude du niveau phosphore assimilable et de la fertilité phosphorique des zones céréalières de la région du Kef. ES 289 , Direction des Sols, Ministère de l'Agriculture.
[11] Zantour (M.), 1989. Evolution des fumures phosphatées dans les sols calcaires. Bulletin « Sols de Tunisie «, n° 13. Direction des Sols, Ministère de l'Agriculture.
[1] Ministère de l'Agriculture 2000- 1999 -1998 - rapports de la DGPDIA.
[2] Poncet, J. 1958. Les repports entre les modes d'exposition agricole et l'érosion des sols en Tunisie, Ministère de l'Agriculture, 171 p.
8.1 > 8.
Country in general
General data on Tunisia
http://www.fao.org/Gender/Static/CaseSt/Tun/tun-e-06.htm
Tunisia Geography 2000
http://www.photius.com/wfb2000/countries/tunisia/tunisia_geography.html
WeatherHub : Tunisia
http://www.weatherhub.com/global/ts_info.htm
WorldAtlascom : Tunisia
http://www.worldatlas.com/webimage/countrys/africa/tncia.htm
TunisiaOnline : Environment
http://www.tunisiaonline.com/environment/environment3.html
Land and Water resources
Tunisia : Draft environmental profile on Tunisia
http://www.wri.org/wdces/tu80_109.html
IDRC: Cairo : Water Demand Site
http://www.idrc.ca/waterdemand/idrcreports_e.html#Gestion
Land and Water Brightspots
Info-Prod Research (Middle East): Tunisia
http://www.infoprod.co.il/country/tunis2i.htm
history:
[13/03/03] on-line
[29/07/04]add link to Directory of Soil Institutions and Experts in Africa on 2.2.1