Land resources information
in Tunisia

Summary

Agricultural development in Tunisia is related to the economic growth and better use of natural resources in the North-African and Mediterranean environment. Programmes and strategies for 10 years were elaborated on:

• mobilization and national use of hydraulic resources;
• conservation and protection of the rural environment (soil and water conservation, reafforestation, pastures);
• improvement of the productivity of the agricultural sector (large-scale crops, arboriculture, olive growing, animal health, etc.);
• implementation of plans relative to the intensification of sectors of agricultural production

Numerous pedological studies based upon prospecting, photo interpretation, laboratory analyses, remote sensing and the results of monitoring stations, have been realized in Tunisia over more than half a century and cover almost all the territory. 10.4 million ha, 65 percent of the country is covered by maps. These studies aim to better knowledge of the country's soil resources in order to use them rationally for agricultural purposes. Thus, at the African level, Tunisia is among the best studied countries in Africa, with 636 pedological studies; 317 special pedological studies; 2086 preliminary prospecting studies; and 18 issues of Sols de Tunisie, the bulletin of the Direction of Soils. All these documents are classified and available in the library of the Direction of Soils.

Tunisia, with a total area of 16.4 million ha, 9 000 km long and 542 km wide, presents, from north to south, a strong bioclimatic gradient. Among the 16.4 million ha of its total surface, Tunisia has at present about:

• 3.5 million ha of agricultural lands (21 percent of the total area), which are divided up as follows:
• 1.3 million ha for annual crops on the average, which may reach 1.7 million ha in rainy years;
• 2.0 million ha for arboriculture;
• 1.0 million ha of scrub and forest rangelands, of which 0.7 million ha of forests;
• 6.0 million ha of rangelands (decreasing resources);
• 0.4 million ha of steppe (decreasing resources);
• 5.0 million ha (30 percent of the total area) of soils not suitable for cultivation, composed of raw mineral soils and saline soils (salt lakes, saline depressions, etc.).

In Tunisia land degradation is due to water erosion (37 percent) and wind erosion; the two forms of erosion are often associated.

The medium- and long-term objectives concern first, the diagnosis of the state of soil resources in Tunisia, and a better use and the durable management of soil resources in the environment of Mediterranean and desert regions. In the second place, study of the following subjects:

• Soils and systems of soils in the different agro-ecological environments;
• Original organization of soils in the landscapes;
• Problems of the use of soils by man (irrigated and dry farming)

The country has a diversity of landscapes:

• forests and steppes;
• lakes and saline depressions;
• the desert;
• the littoral plains

In the future, soil information systems based on well structured data bases and geographic information systems (GIS) will provide easier access to the available information and enable technicians and researchers to understand the functioning and evolution of the different soils. At present, the computer science unit is able to realize the following studies:

• pedologic cartography for dry and irrigated farming systems ( mapping of soil types and soil use, determination of geo-referenced coordinates by GPS, digital elevation models, etc.);
• mapping of water erosion risk by use of Arc Info and Arc View. Because of insufficient human resources, the areas studied remain limited to a few landscape units in the North.

The programme "Spatially referenced information system for irrigated systems in Tunisia" realized by the Direction of Soils with the collaboration of the Research Institute for Development (IRD, France) and applied to the low valley of Medjerda in north-eastern Tunisia presents results concerning hydro-agricultural development. It enables the integration of georeferenced pedologic, hydraulic and agronomic data aiming at establishing a model for the functioning of the developed irrigated system: The GIS contributes largely to the modelization of the data. The goal of the project is improvement of water use at the parcel level with respect to climate, soil type and agricultural practices, in order to find the necessary solutions and choose the actions to be undertaken.

The full Tunisia country report is available at the Gateway Web site:

http://www.fao.org/WAICENT/FAOINFO/AGRICULT/AGL/sw1wpnr/sw1wpnr.htm