Use of treated wastewater with different irrigation methods on pepper crops: evaluation of the impact on yield, quality and soil conditions

Abstract Treated domestic wastewater (TWW) represents a sustainable irrigation water source for the Mediterranean region and other arid and semi-arid areas. This study investigates the implications of using TWW on human health and soil quality over extended periods. Conducted between 2013 and 2015 in Menemen, a vital agricultural area in Izmir, Turkiye, the research focused on irrigating pepper crops using advanced biological wastewater treatment. Two types of water were employed: TWW and freshwater (FW), utilizing subsurface drip irrigation (SDI), drip irrigation (DI), and furrow irrigation (FI) methods. The analysis encompassed various parameters, including fruit yield (FY), fruit dimensions, vitamin C content, titratable acidity (TA), pH levels, and fecal coliform contamination. Key water quality indicators were measured such as pH, electrical conductivity (EC), chemical oxygen demand (COD), biological oxygen demand (BOD), total nitrogen (TN), total phosphorus (TP), and pathogenic microorganisms like E. coli and Salmonella. The results indicated that TWW had elevated E. coli levels, surpassing Turkish standards, particularly in FI, where concentrations reached 8.133 × 10 3 cfu 100 g⁻ 1 . Despite the contamination, the highest pepper yield of 88.2 t ha⁻ 1 was achieved with SDI using TWW. While TWW enhanced pepper production, its high salt content necessitates soil washing before planting to mitigate salinity risks, especially during dry winters. Ultimately, the SDI technique emerged as the safest method for reducing pathogen-related risks in irrigation practices.