ssessment of Actual Irrigation Management in Kalaat El Andalous District (Tunisia): Impact on Soil Salinity and Water Table Level

摘要

The objective of this work is to assess water and soil salinity evolution in the irrigated area of Kalaat El Andalous. Soil salinity, crops yield, water table level and drainage water flow were monitored during the period May 2008-June 2010. The results showed that during irrigation season (May-September 2008), the supplied water amounts for drip irrigated crops (tomato, melon and squash) were higher than crop water requirements. In fact, the soil water content was always equal or higher than the field capacity. Average root zone (0-60 cm) electrical conductivity of the saturated past extract (ECe) was 2.3 dS m -1 , 2.8 dS m -1 and 3.0 dS m -1 in May 2008, May 2009 and May 2010 respectively. But at the irrigation season end, higher electrical conductivity (8.4 dS m -1 ) was recorded in the upper layer (0-30 cm). Along rainfall season, a soil salinity decrease was recorded in fact the average electrical conductivity reached 2.0 dS m -1 . In order to reduce soil salinization (due to accumulated salts during irrigation season ) , farmers use crop rotation including rain fed crops and bare soil. Allover irrigation season, the highest drainage discharge (192 l/h) was recorded on July 2008 when the maximum irrigation water amount was diverted. Water table level shows a sustained rise when irrigation is relatively frequent during summer.