Dhanwinder SinghGupta, Soura Shuvra2021-09-092021-09-092020Gupta, Soura Shuvra (2020). Bioavailability of heavy metals to maize grown in sewage sludge amended soil (Unpublished M.Sc. thesis). Punjab Agricultural University, Ludhiana, Punjab, India.https://krishikosh.egranth.ac.in/handle/1/5810175577Sludge generated from the sewage treatment plants (STPs) has a potential for its use in agriculture, as it contains a good amount of organic carbon as well as macro and micro nutrients. However, due to the presence of heavy metals, its use in agriculture is restricted. If used judiciously, it can become one of the alternates to the organic manures. A field experiment was conducted at the research farm of Department of Soil science, PAU, Ludhiana to evaluate the different rates (0, 2.5, 5, 7.5 and 10 t/ha) of sewage sludge along with three different levels of nitrogen (0, 90, 120 kg N/ha) on dry matter yield of maize (Zea mays var PMH 1) and to study the bioavailability and transformations of heavy metals in post-harvest soil. Application of sewage sludge up to 5 t/ha along with 120 kg N ha-1increased the maize grain and stover yield significantly. The maize grain yield increased from 30 q/ha in absolute control to52.6 q/ha and maize stover yield increased from 67 q/ha to 109.6 q/ha with the application of sludge @5 t/ha along with 120 kg N/ha. Heavy metals (cadmium, chromium, lead and nickel) content in maize grain and stover and their uptake also increased significantly with the increasing rate of sludge application. The mean cadmium, chromium, lead and nickel content in maize grains increased from 0.015 to 0.032 mg/kg, 0.629 to 0.698 mg/kg, 0.157 to 0.195 mg/kg and 0.93 to 1.61 mg/kg, respectively with the highest rate of sludge application. These concentrations were within the respective permissible limit given by FAO/WHO. Sequential fractionation of post-harvest soil samples suggested that proportion of Cd and Pb to their total content significantly increased in the labile fraction of soil pool and percentage of Ni and Cr to total significantly increased in the residual fraction with application of 10 t/ha sludge over control. Application of 5 t/ha could be more sustainable approach for a longer period.EnglishThesis