Effects of recycled wastewater applications with different irrigation practices on the chemical properties of a vertisol

Abstract

The soil degradation caused by the use of low-quality waters in agriculture may be restricted with reorganization of irrigation practices. Therefore, a 2-year study was conducted to determine the changes in chemical and biological properties of soil layers of 0-30, 30-60, and 60-90 cm of a tomato field that was irrigated by recycled municipal wastewater with different drip practices (full, DI: deficit irrigation, and PRD: partial root-zone drying irrigation). The study results showed that the soil electrical conductivity (EC) and exchangeable sodium percentage (ESP) values after the experiment were quite low considering the problematic levels (>4 dS/m for EC, and >15% for ESP), and the organic matter content did not change significantly. The highest N, P2O5, and K2O concentrations were determined in 0-30 cm soil layer for fully irrigated with wastewater, whereas the PRD and DI treatments irrigated with 50% water saving resulted the lowest soil fertility. Wastewater treatment also increased concentrations of micro- and trace minerals, but the toxic element concentrations were in safe limits considering the FAO/WHO and national standards. In this 2-year study, it can be mentioned that treated wastewater applications increase soil fertility owing to the increase in macro and micronutrients. It may be suggested that wastewater treated with PRD and DI applications can be used in case of water shortages. © Copyright 2020, Mary Ann Liebert, Inc., publishers 2020.