Effect of Surface and Subsurface Drip Irrigation with Treated Wastewater on Soil and Water Productivity of Okra (Abemoschus esculentus) Crop in Semi-Arid Region of Tunisia
Under semi-arid conditions, irrigated agriculture faces hard competition for water. It is against this backdrop that appropriate management of irrigation techniques and water resources becomes a major concern. This study investigated the effect of surface (SDI) and subsurface drip irrigation (SSDI) with domestic treated wastewater (TWW) and fresh water (FW) on soil water dynamics, salinity, yield, and mineral nutrition of okra. The experimental design was set-up based on two adjacent plots according to the water quality: Fresh Water (FW) T1 and domestic Treated Wastewater (TWW) T2. Results showed that measured soil water contents (SWCs), under TWW treatment (T2), were greater than their corresponding measurements under FW (T1), and in particular at 35 cm depth. Meanwhile, for both water qualities, soil Electrical Conductivity (EC) registered at 5 cm depth was higher than those measured at 35 cm, with values ranging from 0.14 to 0.36 mS&middot;cm&minus;1 and from 0.20 to 0.47 mS&middot;cm&minus;m for T1 and T2, respectively. Regarding crop yield, a statistically significant increase (p = 0.05) in okra fresh yield was observed when TWW was used. Fresh yield in SDI was 2.55 t&middot;ha&minus;1 and 3.9 t&middot;ha&minus;1 in T1 and T2, respectively. Nevertheless, results indicated that lateral depth did not significantly affect okra fresh yield. Moreover, a significant higher irrigation water productivity (WPirrig) with TWW (1.08 &plusmn; 0.26 and 1.23 &plusmn; 0.18 kg m&minus;1) was observed, which was nearly double those obtained with FW (0.72 &plusmn; 0.33 to 0.78 &plusmn; 0.18 kg m&minus;1). Appropriate use of SSDI with TWW stands as an irrigation management technique to improve yield and irrigation water productivity of okra crops.