*2.1. Site Description*

A field investigation was carried out in the olive (*Olea europaea*) cultivar 'Barnea' orchard of Kibbutz Revivim (31.0436◦ N, 34.7212◦ E), located in the central Negev Desert, Israel. The climatic conditions of the location are of the typical arid type, with cooler night temperatures and hot, dry summers (Figure 2). The mean annual rainfall ranges from 75 to 125 mm [25]. During the 2014/2015 season, the total precipitation was 105 mm and cumulative potential evapotranspiration was 2500 mm (Figure 3). The olive orchard was planted in 1995 and has been irrigated with brackish groundwater (EC = 4.4 dS m−1) since then, for approximately 20 years. Water quality parameters of the brackish irrigation water are presented in Table 1.

During the first 15 years, DI was used but later converted to SDI by placing drip laterals at 20 cm soil depth and about 1 m distance from the tree line with an emitter flow-rate of 4 L h−<sup>1</sup> and 1 m distance between nearby emitters. An initial tree spacing of about 3 × 7 m was first established and after ten years, each alternate tree within a row was uprooted, giving the current spacing of 6 × 7 m. Irrigation was scheduled according to class evaporation pan located nearby the orchard. Specifically, in average, a factor of 35% to 60 % was used to calculate the irrigation amounts from the predetermined cumulative pan evaporation (class A pan) [8]. Accordantly, irrigation intervals were scheduled every 3 days during summer and every 7 days during winter. Approximately, 800 mm plus an excess of 100 mm, as the leaching requirement of irrigation water, was applied annually.

**Figure 2.** Minimum and maximum temperature in Revivim during 2014–2015.

**Figure 3.** Rainfall and potential evapotranspiration (ETo) in Revivim during 2014–2015.


