Salt transfer under irrigation with treated wastewater in semi-arid Tunisia / Salttransport under bevattning med renat avloppsvatten i norra Tunisien
Tunisia is a country with limited water resources and is in need of irrigation to sustain the agriculture. Treated wastewater is used as an irrigation water source in some areas. The use of saline treated wastewater can lead to soil salinization which could pose a serious threat to the agriculture. A field study was performed on a citrus tree field outside the city of Nabeul, Tunisia, to investigate the effects on soil salinity after irrigation using treated wastewater and after rainfall. Electromagnetic induction readings (EM38) in combination with hand auger soil sampling were performed to produce maps over soil salinity (ECe) over this field. This field cannot be considered as saline, the ECe is less than 4 dS/m. However, the observed salinity can still affect the citrus production in a negative way. No clear increase in salinity after irrigation could be seen, although it was expected according to theory. This can be due to the inclination of the field or the irrigation practices. The rainfall might have leached the upper layer in the soil but not the deeper layers where the salinity increased. Further studies are needed to make any clear conclusions about the effects on soil salinity in this field.