Author's personal copy Scientia Horticulturae 126 (2010) 345–350 Contents lists available at ScienceDirect Scientia Horticulturae journal homepage: www.elsevier.com/locate/scihorti Effects of irrigation with treated wastewater on olive tree growth, yield and leaf mineral elements at short term Saida Bedbabis a,∗ , Giuseppe Ferrara b , Béchir Ben Rouina c , Makki Boukhris a a Faculty of Sciences, Department of Biology, University of Sciences, P.O. Box 802, 3038 Sfax, Tunisia b Dipartimento di Scienze delle Produzioni Vegetali, University of Bari ‘Aldo Moro’ Via Amendola 165/A, 70126 Bari, Italy c Olive Tree Institute, P.O. Box 1087, 3000 Sfax, Tunisia article info Article history: Received 22 April 2009 Received in revised form 24 June 2010 Accepted 14 July 2010 Keywords: Olea europaea L. Treated wastewater Irrigation Shoot growth Salts Heavy metals abstract In arid regions, such as Tunisia, the reuse of treated wastewater (TWW) in agriculture can be a sustainable solution for water scarcity. A two-year field experiment was conducted in order to investigate the short- term effects of TWW on olive growth, yield and concentration of total nitrogen (N t ), potassium (K), phosphorous (P), and heavy metals (i.e. Zn, Mn, Pb and Cd) in olive leaves. Olive trees were subjected to the following irrigation treatments: (i) trees irrigated with well water (WW) and (ii) trees irrigated with treated wastewater (TWW). For both treatments, the TWW and WW were applied at a rate of 4.5 m 3 day -1 tree -1 (5000 m 3 ha -1 year -1 ). After two years, non-significant injuries caused by salts and/or heavy metals were observed on shoot growth of trees irrigated with TWW. The application of TWW significantly increased concentration of N t , P and K in the leaves, whereas heavy metals (Zn and Mn) showed a significant increase only after the second year of irrigation. © 2010 Elsevier B.V. All rights reserved. 1. Introduction The Middle East and North Africa are considered as the driest region in the world and freshwater availability in those areas is very low (World Bank, 1996). According to several authors (Gregory, 2000; Bedbabis et al., 2009), the use of brackish water or recycled wastewater in agriculture may help in reducing the problem of the limited availability of freshwater. Many studies (Rejeb, 1992; Chaabouni et al., 1997; Yadav et al., 2002) showed that the application of treated wastewater (TWW) at a reasonable rate improved growth and productivity of some herbaceous species. However, the main problem that can arise from excessive and continuous application of TWW is phytotoxicity due to high content of salts and heavy metals, which may pose a health risk for human beings or livestock (Rutkowski et al., 2006; Toze, 2006). TWW is from domestic (12%) and industrial (88%) sources and is typically reclaimed at the secondary level using biological processes. These processes consist of eliminating biodegradable material by transforming it into microbial residues. Secondary treatments remove dissolved and colloidal organic matter using an aerobic-biological treatment. The aerobic-biological treatment ∗ Corresponding author at: Olive Tree Institute, P.O. Box 1087, 3000 Sfax, Tunisia. Tel.: +216 74 275 541; fax: +216 74 274 437. E-mail address: saida bedbabis@yahoo.fr (S. Bedbabis). is performed in the presence of oxygen by microorganisms which metabolize the organic matter, thereby producing more microor- ganisms and inorganic end-products (CO 2 , NH 3 and H 2 O). Studies on the effect of TWW on olive’s growth and productivity are scarce (Charfi et al., 1999; Gharsallaoui et al., 2006). The topic should be better investigated in countries like Tunisia where olive trees play an important role for the economy but water availability for agricultural purposes is very limited. The objective of our study is to verify if an irrigation with TWW can be considered a good source of water and fertilizers source for ‘Chemlali’ olive trees with no phytotoxicity effects. 2. Materials and methods 2.1. Experimental plots, soil and climatic data The study was carried out from February 15, 2003 to Novem- ber 26, 2004 in an experimental olive grove of ‘Chemlali’ variety. Two experimental plots were considered: one plot irrigated with well water (WW) and the other irrigated with treated wastewater (TWW). The two experimental plots were located in the region of Sfax (34 ◦ 43N, 10 ◦ 41E), in Central-Eastern Tunisia. In order to deter- mine the influence of the two different irrigations approaches on growth and productivity, the trials were planned using the same agronomic techniques. Each experimental plot consisted of nine Chemlali olive trees, spaced 24 m × 24 m, irrigated either with TWW or WW (Table 1), 0304-4238/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.scienta.2010.07.020