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 w...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.展开更多
The Tunisian oases face serious problems of waterlogging and salinization caused by mismanagement of water and soil resources and the reduced discharge of drainage water. The oases space is based on a fragile balance ...The Tunisian oases face serious problems of waterlogging and salinization caused by mismanagement of water and soil resources and the reduced discharge of drainage water. The oases space is based on a fragile balance between water, soil and man, which is now changed by modem irrigation and drainage systems. The oases pump most of their water from deep aquifers and only to a small degree from shallow aquifers. The quality of the irrigation water and the presence of a shallow saline water table are the main causes of salinization of the oases. Concerning the salt-affected landscapes and hydro-saline dynamic, the authors distinguish an equilibrium dynamic of salts to the parcel which depends on water management, and an equilibrium dynamic at the level of the basin watershed which is powered by drilling and ending in hypersaline depressions. For the management of salinization and waterlogging, a combination of agricultural management techniques are used, the first being modem methods of irrigation and drainage. Other, less used methods are sandy amendment, the reuse of drainage waters, geothermal waters and of treated wastewater.展开更多
文摘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.
文摘The Tunisian oases face serious problems of waterlogging and salinization caused by mismanagement of water and soil resources and the reduced discharge of drainage water. The oases space is based on a fragile balance between water, soil and man, which is now changed by modem irrigation and drainage systems. The oases pump most of their water from deep aquifers and only to a small degree from shallow aquifers. The quality of the irrigation water and the presence of a shallow saline water table are the main causes of salinization of the oases. Concerning the salt-affected landscapes and hydro-saline dynamic, the authors distinguish an equilibrium dynamic of salts to the parcel which depends on water management, and an equilibrium dynamic at the level of the basin watershed which is powered by drilling and ending in hypersaline depressions. For the management of salinization and waterlogging, a combination of agricultural management techniques are used, the first being modem methods of irrigation and drainage. Other, less used methods are sandy amendment, the reuse of drainage waters, geothermal waters and of treated wastewater.
