The Effect of Different Ratios Municipal Wastewater Applied in Irrigation Water on Some Physical and Chemical Properties of Soil

The aim of this study was to investigate the effects of using different combinations of waste water and well water with the approach of using unconventional water on some physical and chemical properties of soil. For this purpose، a factorial experiment was conducted in a completely randomized design with three factors. The main factors include irrigation with waste water to well water ratio in 5 levels including I1 (control: irrigation with well water)، I2 (75% well water and 25% waste water)، I3 (50% well water and 50% waste water)، I4 (25% well water and 75% waste water) and I5 (irrigation with 100% waste water)، the second factor includes two soil depths (0-30 and 30-60 cm) and the third factor includes the duration of irrigation in 5 levels (zero، 1، 2، 3 and 4 months). The results showed that soil salinity، pH and organic carbon increased with increasing irrigation time. The highest increase in salinity was observed after 4 months in I5 treatment with about 37% increase compared to the control treatment. The amount of organic carbon in treatments I4 and I5 in the surface layer increased by about 60% compared to the subsurface layer. However، waste water consumption improved hydraulic conductivity compared to well water، so that its amount increased in I5 treatment، at surface and subsurface depth by 76.7% and 80%، respectively، compared to the control treatment. The findings of this study showed that the use of treated wastewater as one of the unconventional water sources، despite increasing soil salinity، can increase organic carbon and improve soil permeability.