Effects of sewage sludge used as fertilizer on the yield and chemical contents of Lucerne (Medicago Sativa L.) and soil

Abstract

This study was conducted to determine the effects of sewage sludge (SS) used as fertilizer at different concentrations (control, 20 kg ha-1 nitrogen (N), 30,60 and 90 ton ha-1 SS, 20 kg ha-1 N + 30 ton ha-1 SS, 20 kg ha-1 N + 60 ton ha-1 SS and 20 kg ha-1 N + 90 ton ha-1 SS) on lucerne yields and chemical features. For this purpose, an increasing level of SS was applied to the soil samples. The residuals of some heavy metal (Hg, Cr, Fe, Ni, Zn, Mn, Pb, Cu, Co, and Se) and macro element (K, Ca, Na, Mg, C, and S) concentrations were measured in the plants and soils. According to the results of this study, SS, when applied to soil in increasing amounts, raised the mineral matter contents of the plants, which favorably affected plant growth. Consequently, it affected the herbage yield, increasing the yield in parallel with the increasing SS concentrations. Applying N with the SS positively influenced the heavy metal contents of the lucerne and residue in the soil. Additionally, the heavy metal contents were found at below critical levels in both the soil and plants. Therefore, SS application as fertilizer used in appropriate concentrations did not pollute the soil very much, but did lead to an increase in plant products.