Effects of different sewage sludge applications on heavy metal accumulation, growth and yield of spinach (Spinacia oleracea L.)

Abstract

In this study, we present the response of spinach to different amendment rates of sewage sludge (0, 10, 20, 30, 40 and 50 g kg) in a greenhouse pot experiment, where plant growth, biomass and heavy metal uptake were measured. The results showed that sewage sludge application increased soil electric conductivity (EC), organic matter, chromium and zinc concentrations and decreased soil pH. All heavy metal concentrations of the sewage sludge were below the permissible limits for land application of sewage sludge recommended by the Council of the European Communities. Biomass and all growth parameters (except the shoot/root ratio) of spinach showed a positive response to sewage sludge applications up to 40 g kg compared to the control soil. Increasing the sewage sludge amendment rate caused an increase in all heavy metal concentrations (except lead) in spinach root and shoot. However, all heavy metal concentrations (except chromium and iron) were in the normal range and did not reach the phytotoxic levels. The spinach was characterized by a bioaccumulation factor <1.0 for all heavy metals. The translocation factor (TF) varied among the heavy metals as well as among the sewage sludge amendment rates. Spinach translocation mechanisms clearly restricted heavy metal transport to the edible parts (shoot) because the TFs for all heavy metals (except zinc) were <1.0. In conclusion, sewage sludge used in the present study can be considered for use as a fertilizer in spinach production systems in Saudi Arabia, and the results can serve as a management method for sewage sludge.

The evaluation of sewage sludge application as a fertilizer for broad bean (Faba sativa Bernh.) crops

“…Additionally, the organic nitrogen mineralization incorporated by SS generates protons by nitrification and mineralization of S rich compounds, resulting in a decrease in soil pH (Kirchmann, Pilchmayer, & Gerzabek, ). Yilmaz and Temizgül () and Eid, El‐Bebany, et al., ; Eid, Alrumman, et al., also reported a decrease in pH and a rise in salinity attributable to different rates of SS amendment in the soil.…”

“…In our investigation, soil OM increased with the rate of SS addition, achieving its greatest value with the maximum dose (150 t/ha). Eid, El‐Bebany, et al., ; Eid, Alrumman, et al., verified that the addition of SS to soil cultivated with spinach and cucumber promoted a rise in the soil content of OM. The soil OM content in nonamended soil was 1.3%, compared to 1.6, 1.7, 1.9, 2.1, and 2.4%, which corresponded to 1.2‐, 1.3‐, 1.5‐, 1.6‐, and 1.9‐fold increases, respectively, at 30, 60, 90, 120, and 150 t/ha SS amendment rates.…”

“…Soil surface samples (0–20 cm) were collected from neighboring cultivated fields (sandy loam; Khan, Hussein, Khan, & Khan, ), while dewatered activated SS was taken from the Wastewater Treatment Plant of Abha City. The Wastewater Treatment Plant of Abha City processes around 41,275 m 3 of wastewater daily using tertiary treatment, and the equivalent dry SS production was assessed as 90 ton per day with daily dumping (Eid, El‐Bebany, et al., ). The soil and SS samples were air‐dried, uniformly ground to obtain a homogenous mass and sieved through a 2‐mm sieve.…”

“…Due to population increase, urbanization and industrialization, wastewater production and the quantity of SS have expanded fundamentally (Kominko, Gorazda, & Wzorek, ). SS contains micro‐ and macro‐nutrients that are important for plant development and may be a valuable supply of OM for generality cultivated lands (Eid, El‐Bebany, et al., ). However, SS may contain high levels of pollutants, either organic and/or HMs (Rastetter & Gerhardt, ).…”

“…Thus, agricultural soil amendment with SS can enhance soil physical characteristics and fertility, which ultimately improve crop production (Koutroubas, Antoniadis, Fotiadis, & Damalas, ). Furthermore, Eid, El‐Bebany, et al., ; Eid, Alrumman, et al., have suggested that SS could provide a appreciated fertilizer, in the forthcoming, that might promote yield, growth, and plant constituents of crops. Additionally, according to Brown and Leonard (), reutilizing organic carbon present in SS is significant for the carbon sequestration fixed from the atmosphere in soils, and it is important for the mitigation of climate change.…”