background and aim: due to the quantitative and qualitative reduction of the country's water resources and the droughts of the last few years, the use of effluents and sewage by farmers to irrigate fields and gardens has been considered. this research was conducted in order to investigate the effect of irrigation with urban sewage effluent on some physical and hydraulic characteristics of soil in the northern region of isfahan. soil hydraulic parameters, such as infiltration is very important in the optimal management of furrow irrigation, and its measurement is necessary for these farms.
method: this research using urban sewage effluent and in the form of a factorial statistical design based on a completely randomized block with three levels of irrigation treatment (irrigation with wastewater treatment plant effluent, intermittent irrigation with effluent and well water, and irrigation with well water) in the region north of isfahan, was done.
&results:different irrigation treatments had no significant effect on the amount of soil moisture in crop capacity (fc) and permanent wilting point (pwp). the amount of apparent specific gravity was significantly increased at the level of 1% in the irrigation treatment with well water and decreased in the irrigation treatment with wastewater. the hydraulic conductivity measured in the irrigation treatment with effluent was about 20% higher than the irrigation treatment with well water. also, the greatest amount of difference between advance and retreat time was in the treatment of irrigation with wastewater (68.4 minutes) and the lowest was related to irrigation with well water (50.8 minutes). it showed that the chance of water infiltration into the soil was greater in the wastewater treatment than in the treatment irrigated with well water. the general trend of the coefficients of the kostiakov-lewis infiltration equation in the treatment of well water was a decrease (about 58 and 60% for k and a coefficients, respectively). the highest amount of average cumulative infiltration was related to wastewater and the lowest amount was related to periodic treatment. the rate of water infiltration into the soil in the effluent irrigation treatment was about 0.001 m/min and in the well water irrigation treatment was about 0.0008 m/min, which is approximately equivalent to a 73% decrease in infiltration rate.
conclusion: based on the results obtained from this research, the effect of irrigation with wastewater and well water on different physical characteristics of the soil depends to a large extent on the chemical characteristics of the well water and wastewater and the basic nature of the wastewater. the existing sodium ion caused the destruction of the soil structure and the blockage of coarse pores, and in general, it caused the volume of voids and pores in the soil to decrease and become denser, and finally, the apparent specific gravity of the soil increased. the reason for this can be attributed to the increase in soil organic matter as a result of wastewater consumption, as well as the increase in soil calcium and magnesium concentration, the increase in soil microbial activity and the improvement of soil structure.