Agriculture sustainability in arid lands of southern Tunisia: Ecological impacts of irrigation water quality and human practices
2020
Dhaouadi, Latifa | Besser, Houda | Wassar, Fatma | Kharbout, Nissaf | Brahim, Naima Ben | Wahba, Mohamed As | Kang, Yaohu Kang
Groundwater resources in southwestern Tunisia are facing serious quantity and quality degradation. Given that they are the only source used for oasis irrigation, serious impacts on the soil of the region are expected. Accordingly, the main objective of this study is to evaluate the suitability of the sampled water from the Complex Terminal aquifer for irrigation purposes and to determine the potential impacts of their long‐term use within the present agricultural practices on soil properties. The calculated ionic ratios indicate different classes ranging from permissible to unsuitable waters with respect to alkalinity standards (sodium adsorption ratio from 3.68 to 9.34, %Na from 36.7 to 61.2, and rill erodibility from 0.48 to 1.43). Water samples present high values of electrical conductivity, total dissolved solids, and potential salinity, about 54.5, 29.4, and 32.2%, respectively, which indicates serious salinity hazard. All the sampled waters may induce corrosion and clogging problems as deduced from the calculated light dynamic penetrometer and total hardness indices. The weighted water quality indices results (Canadian Water Quality Index and the irrigation water quality index) confirm the poor quality of the used irrigation water. The results of this study coupled with field investigations indicate that the cumulative impacts of low water quality and poor agricultural practices have damaged the total oasean ecosystem.
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