Monitored Sewage Sludge Application Improves Soil Quality, Enhances Plant Growth, and Provides Evidence for Metal Remediation by Sorghum bicolor L. (Jun, 10.1007/s42729-021-00524-x, 2021)

This work aims at studying the possibility of the safe application of sewage sludge (SS) biosolids as low-cost soil fertilizer to improve soil properties and crop productivity. In the present study, Sorghum bicolor was cultivated in soil amended with SS (0, 10, 20, 30, 40, 50 g/kg) to investigate its impact on soil quality and sorghum yield. Applying SS rates significantly increased growth parameters, total biomass, and absolute growth rate compared to the plants grown in the non-amended (control) soils, whereas 30 g/kg SS had the highest values and was considered as a recommended dose. The induced growth at 30 g/kg SS was accompanied with a significant increment in metals contents in roots, stems, and leaves, and had normal safe limits in the produced grains. After harvesting, the soil quality was improved, and its pH value decreased from 8.4 to 7.7, offering an increased availability of micronutrients. Furthermore, amending S. bicolor with 30 g/kg SS elevated bioaccumulation factor (BF) values over 1 for Cu, Ni, Zn, and Cr compared to the control, indicating its remediating capability with values of 2.32, 1.97, 1.42, and 1.15, respectively. Alternatively, at the recommended SS dose, the upper uptake of Pb significantly increased in the leaves having translocation factor (TF) value of 1.18. The current work proposes that soil amendment with 30 g/kg SS is recommended to enhance soil fertility and plant yield, with no health risks when eating the produced grains, with potential heavy metal phytoextracting by S. bicolor .