The field experiment was conducted on an 1800 m2
(60 m 30 m) field block, which was divided into 18 sub-plots of
50 m2 each (5 m 10 m). The soil of the experimental site was
coarse nutrient poor sandy with very low water holding capacity
(Fig. 1). The compost at the rate of 3.0 kg m2 was applied to
improve water holding capacity and aggregation properties of
the soil. After complete mixing of the compost, the field was
leveled using soil planker. Six commonly used kitchen vegetables,
Tomatoes (Lycopersicon esculentum Mill.), Eggplant (Solanum
melongena), Lettuce (Lactuca sativa), Spinach (Spinacia oleracea
L.), Carrot (Daucus corota L.), and Radish (Raphanus sativus) were
selected for this experiment.
The amount of water applied to each crop was based on its
crop water requirement, which was calculated using Penman-
Monteith equation using climatic data from the meteorological
station installed at the ICBA experimental farm. The surface drip
irrigation system was used for irrigating vegetables and irrigations
were applied twice a day through an atomized system using
Rain Bird timer and solenoid valve through 12 AWG solenoid
cable. All vegetables were irrigated with the tertiary-level treated
municipal wastewater (TWW) obtained from the Dubai Municipality.
Tertiary-level treatment does not completely screen out
the presence of bacteria such as total Colifoirms and Escherichia
coli from the effluent nor does it address the concentrations of
heavy metals especially Cu, Fe, Zn and Cr, which could pose a
safety hazard if high. Tertiary level treatment is mainly done to
remove phosphorus and nitrogen which causes eutrophication.
The chemical and biological properties of the TWW used in this