Treated Wastewater Irrigation Promotes the Growth and Nodulation of Acacia Species

The scarcity of irrigation water is one of the vital factors limiting crop production in arid countries. The critical shortage of water necessitates the development of new water sources, and the use of wastewater is considered one of the best solutions for solving this water scarcity. An experiment was conducted to investigate the effect of primary treated wastewater irrigation on growth parameters, nodulation, macro and micronutrients for Acacia ampliceps (Maslin.) and Acacia origena (Hunde.) seedlings grown in the Dirab Valley, South of Riyadh City. The study included four irrigation treatments: municipal water plus Rhizobium inoculum (MWR), primary treated wastewater plus Rhizobium inoculum (PTWR), municipal water only (MW), and primary treated wastewater only (PTW). The results revealed that the PTWR and PTW treatments were effective for increasing the growth parameters and nodulation of the Acacia seedlings. The combination of primary treated wastewater and inoculation with Rhizobium significantly improved the growth parameters, nodulation, and nutrient content of the seedlings. Overall, the combination of treated wastewater and Rhizobium can be used as a potential source of nutrients and water for tree legume plantations in the arid areas of Saudi Arabia.