Effects of different waste materials on corn growth, mineral nutrition and heavy metal concentrations on canola-remediated and non-remediated soil

In this study, it was aimed to achieve two main objectives. Firstly, it was aimed to increase the heavy metal concentration of the soil by applying different waste materials and to remediate the soil by exploiting these heavy metals with canola (Brassica napus L.). Secondly, it was aimed to investigate the effects of the used waste materials on the growth, mineral nutrition and heavy metal concentration of corn (Zea mays L.) grown on canola-remediated and non-remediated soils. In this study conducted as greenhouse experiment, five waste materials including composted biogas fermented material, pelleted biogas fermented material, alkaloid processing solid waste, urban sewage sludge, and industrial sewage sludge, were applied to the pots containing 4 kg soils at the rates of 0, 2, and 4 tons/da. The application of these waste materials positively impacted the growth of canola plants, increasing both their dry weights and mineral concentration with the escalating doses. Canola effectively accumulated significant amount of heavy metals, and the extractable and total amounts of heavy metals remaining in the soil were within the permissible limits for agricultural purposes. Regarding the corn experiment, the waste material amendments similarly enhanced the growth, dry weight, and nutrient concentration of corn plants, with additional support from NPK fertilization. Although the phytoremediation stage had no significant effect on corn growth, it improved the mineral nutrition of the plants. As a result, it was seen that canola can be successfully used for phytoremediation purposes in soils contaminated with heavy metals. At the same time, it was determined that the waste materials used in the study increased the growth and mineral nutrition of the plants without causing heavy metal damage. In addition, it was seen that the waste materials used in the trial positively affected the growth and mineral nutrition of corn in a way that would support chemical fertilizers. Finally, it was determined that the materials used did not pose an ecological risk or toxicological threat in terms of the heavy metals examined after at least one application under these conditions.