Dill (Anethum graveolens L.) response to sewage sludge amendment and its impact on growth and heavy metal accumulation

Abstract

Abstract In this study, an attempt was made to assess the effect of sewage sludge amendment (0, 10, 20, and 30 g/kg of soil) on dill plants (Anethum graveolens L.) cultivation using pot-scale experiments. The experiments were conducted under greenhouse conditions for 59 days and the effect of sewage sludge on soil properties as well as dill growth, productivity, and nine heavy metals (HMs) accumulation were studied. The results showed that out of the tested treatments, 10 g/kg sewage sludge application gave the best results in terms of maximum plant height (21.84 cm), number of leaves per plant (5.80), shoot biomass (0.23 g DM/plant), root biomass (0.09 g DM/plant), total biomass (0.31 g DM/plant), and absolute growth rate (0.006 g DM/day). Additionally, increased sewage sludge amendment significantly (p < 0.05) enhanced HM accumulation in dill roots and shoots, with the highest treatment rate (30 g/kg) consistently yielding the most pronounced effects across multiple HMs. Sewage sludge amendments reduced bioaccumulation factors (BAF) and translocation factors (TF) for Cd, Fe, Mn, Ni, and Zn in dill plants, indicating lower metal uptake and translocation to shoots with increased sludge treatment, while correlation analysis revealed that soil properties like organic matter and pH strongly influenced heavy metal bioavailability and accumulation. Overall, the present study provides insights into optimizing sewage sludge amendments for sustainable agriculture while mitigating the risks of HM contamination in dill crops.