Micronutrient and heavy metal bioaccumulation in Bermuda grass (Cynodon dactylon L. Pers) grown in calcareous soil using stabilized and dried sewage sludge

This study examines the micronutrients and heavy metal bioaccumulation in Bermuda grass (Cynodon dactylon L. Pers), grown in two different types of calcareous soil (CS) with the application of stabilized and dried sewage sludge (SS). At the end of the growth period, the Fe, Zn, Mn and Cu (micronutrients) concentrations in the substrate have increased. Furthermore, it was determined that the total Fe, Zn, Mn and Cu concentrations were higher in CS1 compared to CS2. For the heavy metals the concentrations of Ni and Cr have increased, and the concentration of total Cd has slightly but significantly decreased. The total Pb concentration was below the detection limit (DL for Pb <0.03 mg kg-1). It was determined that the total Ni, Cr and Cd concentrations were higher in CS1 than in CS2. In the aerial biomass of the Bermuda grass, the Fe and Zn concentrations have increased with increasing SS applications, whereas Mn concentrations have decreased. Ni, Cr, Cd and Pb concentrations were unaffected by SS applications for both types of CS. The bioconcentration factor (BCF) values for the shoot of the plant (BCFFe, BCFZn, BCFMn, BCFCu, BCFNi, BCFCr, BCFCd) were determined to be below the critical limit of 1. The application of sewage sludge has not resulted in bioaccumulation above critical limits in the shoot of the plant. However, considering Bermuda grass substrate, it can be suggested to add sewage sludge to the calcareous soil in amounts between 20–40 t ha-1, considering its long-term remanence.