摘要
In semi arid and arid countries, the increase in production needs sometimes using brackish/saline water for irrigation. In Kairouan and Mahdia （Centre of Tunisia）, most of the irrigated areas are by pumping ground water from wells and in many cases, water has more than 4 g of salt per liter. To improve farmers＇ income through using efficiently brackish/saline and rare water, applied research programme was carried out. The methodology adopted was based on selection of six farmers＇ parcels. Behind water quality and quantity, soil salinity and crop response, the crop cost was studied： initial and final characterization and frequently controlled. Three different water regimes were observed induced three salinity regimes： an exclusively irrigated regime in summer based on using saline water producing continuous accumulation of salts, an irrigated-rained regime in autumn/spring based on alternated saline and fresh water inducing cyclic accumulation and leaching of salts and a rained regime in winter based on fresh water with continuous leaching of salts. At the short term, soil salinity increased under irrigation until equilibrium with the irrigation water quality and decreased by rain which produced an important salts leaching in a very short time. Many tons of salts were added to the initial stock in summer season and most of them are leached to the subsoil under irrigation and by rain in the winter. Salinization affected the deep layer and on the long term, salinization of the aquifer might occur. An important crop yield decrease for the summer crop was obtained but the socio-economic aspect appeared as an important factor conditioning the use of saline water.
