Irrigation Uniformity Impacts on Water Use Efficiency and Soil Salinity: Case Study of Tomato Crop under Trickle Irrigation System in the NorthEast of Tunisia

Water distribution uniformity remains one of the most used criteria for irrigation performance evaluation. In this paper, the effects of emitters’ discharges spatial-temporal variations on water supply and salt accumulation underneath trickle irrigated crop were assessed. The survey was performed in a private tomato plot in Kalaat El Andalous district (northern-east of Tunisia). Emitters’ discharges spatial variation measurements were made according to Keller and Karmeli method. These measurements were repeated four times throughout irrigation season. Recorded results show that outlets flow rates were significantly lower (-23% to -62%) than their nominal value (4 l/h) for all tested emitters. In fact, emitters’ discharges heterogeneity, recorded within four sites, were 3 l/h, 2.5 l/h, 2 l/h and 1.5 l/h. Nevertheless, for the same locus, emitter discharge variation ranged between -3% and +3% during the irrigation season. Consequently, applied water amounts were ranging between -48% to +6% of the needed water volume with an average uniformity coefficient of 71%. Because of such water supply spatial-temporal heterogeneity, salts leaching fractions were ranging between 8% and 69% of the total loaded salts amount whereas accumulated fractions were ranging between 21% and 90%.