Soil Properties and Trace Elements Contents Following 40 Years of Phosphate Fertilization

Long-term application of P fertilizers may eventually result in excess and/or toxic accumulations of trace elements and microelements in soil. The effect of monoammonium-phosphate (MAP) on basic soil properties (pH, CEC, texture), the total content of C, N, and F, hot acid-extractable Cu, Zn, Ni, Cr, Pb, Cd, Co, As, Hg, and F, and the content of extractable macro- and trace elements (P, K, Ca, Mg, Al, Fe, Zn, Cu, Ni, Pb, Cd, F) were studied on a Stagnosol soil. Phosphate fertilizer had been applied (26, 39, and 52 kg P ha–1) over a 40-yr period. Phosphorus fertilization significantly decreased pH and increased clay content of the soil. Increases were detected in available P, exchangeable Al, Ca, cation exchange capacity (CEC), and clay content. The content of hot acid-extractable Pb increased, whereas the content of diethylenetriaminepentaacetic acid–extractable Pb decreased in accordance with applied rates of MAP. The status of some hot acid-extractable trace elements (Cu, Zn, Ni, and Co) did not change after 40 yr of MAP application, whereas Hg and Cd increased. However, despite the statistically significant increases in the amounts of some potentially toxic elements, they did not accumulate to concentrations considered toxic as overall concentrations are far below the maximum allowed concentrations for natural unpolluted soils.