Elemental content of soil,sorghum and wheat on sludge-injected agricultural land

The objective of this research was to determine the uptake of heavy metals by plants grown on sludge-injected soil. The study took place at the sludge farm owned by the Manhattan, Kansas, sewage treatment plant, where sludge has been injected since 1976. Soil and two crops, sorghum (Sorghum bicolor L. Moench.) and winter wheat (Triticum aestivum L. em. Thell.), were sampled in 1980 after a total of 128 t ha^?1 of sludge (dry-weight basis) had been added to the soil (32 t ha^?1 year^?1). The control area, a farm next to the sludge farm, received only inorganic fertilizer. Four non-essential elements were analyzed (Cd, Cr, Ni, Pb), as well as nine essential elements (N, P, K, Ca, Mg, Cu, Fe, Mn, Zn).Soil in sludge-fertilized fields had more N, P, K, Mg, Fe, Cu, Mn, Zn, Cd, Cr and Ni than did soil from the control fields. In general, concentrations of essential elements in plants grown on sludge were similar to concentrations of essential elements in plants grown with inorganic fertilizer. Concentrations of non-essential elements were also similar, except for the following five exceptions, in which the sludge-treated plants had a higher concentration of the element than did the control plants: Cd in stems of sorghum; Cr in roots of wheat; Ni in roots and grain of wheat; and Pb in roots of wheat. Nickel in grain of wheat grown with sludge was within normal concentration ranges. Cadmium was at low levels in all plants, which indicated that, when sludge was layered below the surface of the soil, transfer of Cd from the soil to the plants was small. Sludge-injection appeared to be an effective method for fertilizing plants.