Evaluation of urban treated wastewater and irrigation method on growth indices of landscaping plants in arid and semi-arid regions

Abstract

Today water scarcity in the agriculture has become a major problem. Sousing wastewater in the agricultural farms, gardens and landscapes has attracted much attention. In this research, the effects of irrigation with the urban treated wastewater were studied on the Laurus nobilis L. and the Buxus sempervirens L. plants. The irrigation treatments were: T1–Furrow irrigation with normal water, T2: DI system with treated wastewater (drip irrigation), T3–SDI system with treated wastewater (sub-surface drip irrigation) at depth of 15 cm, T4–SDI system with treated wastewater at 30 cm depth and T5: Furrow irrigation with treated wastewater. The experiment was conducted in the research field of Isfahan wastewater refinery with the three replications and five irrigation treatments during two years, 2010–2012. Results expressed that the irrigation with wastewater had the positive effects on the growth of both the plants. In the Laurus nobilis L., the greatest number of auxiliary shoots was observed in the surface drip irrigation with the treated wastewater. The height of main stem was increased in the furrow irrigation treatment with the treated wastewater. The analysis of B. sempervirens L. demonstrated that the SDI system with the treated wastewater at the depth of 15 cm had the highest number of branches and plant height. Accordingly the plant growth in the irrigation with wastewater was better than the normal water. In B. sempervirens L., T3 treatment had positive effects on the plant growth in both the stages. Therefore, using of sub-surface drip irrigation at the depth of 15 cm is recommended because of the reduction of the surface soil pollution.