A long-term study of the effects of wastewater on some chemical and physical properties of soil

Nowadays, reuse of wastewater is widespread to prevail over shortage of water and to fertilize agricultural lands. This study was conducted to investigate effects of wastewater on some chemical and physical properties of soil. For this purpose, two farms were selected. These farms are located in the Ghahremanloo region at Urmia plain, West Azerbaijan province located in northwestern of Iran. There is no exact information regarding total amount of wastewater delivered to these lands, but flooding irrigation employing wastewater was applied during growing season. The farms are irrigated with two treatments, including wastewater treatment and freshwater where the surface irrigation method was utilized to plant corn. Experiment design was conducted as completely randomized blocks. Each experiment was repeated four times for both freshwater and wastewater treatments. Results of this study showed that the use of wastewater results in a significant decrease in soil's electrical conductivity (EC), sodium absorption ratio (SAR), and a substantial increase in calcium carbonate equivalent (CCE) and organic materials (OM) of the soil. Besides, the wastewater decreased density of Cu and increased density of Zn, Mn, and Fe significantly, known as heavy metals of the soil. However, the density of these elements in the soil was below detection limit. Bulk density also showed a significant reduction in wastewater usage. Finally, paired t-test and Mann-Whitney nonparametric tests were implemented to validate data.