Accumulation of heavy metals in soil and tobacco after long-term mineral and organic-mineral fertilization

The effect of long-term mineral and organic-mineral fertilization on accumulation of heavy metals in soil and plants was studied in stationary field experiment with continuous tobacco cropping system. Five treatments were selected in this study, including CK (control without fertilization), NP (nitrogen+phosphorus), NK (nitrogen+potassium), NPK (nitrogen+phosphorus+potassium) and NPK+FYM (nitrogen+phosphorus+potassium+manure). Total and available Pb, Cd, Ni, Mn, Zn and Cu content in soil, as well as concentration of the elements in tobacco leaves were determined. The application of mineral fertilizers did not significantly increase the total Pb, Cd, Ni, Zn and Cu content in the soil as compared to unfertilized control. The addition of manure (NPK+FYM treatment) decreased total Ni. There was significant increase of available Ni and Mn in treatment receiving NPK+FYM. A comparison of unfertilized treatment indicated that long-term mineral fertilization had no significant effect on studied metals in oriental tobacco leaves. A considerable decrease in Cd (2.2-2.8 times), Zn (1.7-3.3 times) and Cu (2.2-3.8 times) concentrations in the leaves compared with control without fertilization was detected due to long-term NPK+FYM fertilization. This study demonstrated that the risk of heavy metals’ accumulation in tobacco leaves associated with long-term mineral and organic-mineral fertilization was low.