TRACE ELEMENT CONTENT OF SELECTED FERTILIZERS AND DAIRY MANURES AS DETERMINED BY ICP–MS

Abstract

The trace element composition of representative fertilizers, liming agents, and dairy manures applied on farms in New York was measured because there has been recent concern about toxic metal contaminants in fertilizers and other soil amendments used in agriculture. Selected commercial fertilizers, lime products, and dairy manures were sampled, digested with hydrofluoric acid mixtures, and analyzed for trace element contaminants by inductively coupled plasma–mass spectrometry (ICP–MS). The trace element and heavy metal concentrations of the commercial fertilizers tested were generally low, although the phosphate component of fertilizer blends contained measurable concentrations of several elements of concern, including cadmium (Cd), uranium (U), arsenic (As), and molybdenum (Mo). At the concentrations in these fertilizers, agronomic rates of application would take decades to significantly increase soil concentrations of these elements above background. The manures were found on average to have low concentrations of all trace elements and heavy metals measured, with the important exceptions of copper (Cu) and zinc (Zn), where feed additives and use of Cu sulfate in treating hoof rot may explain the highest concentrations measured. Annual loadings of about 0.35 kg ha⁻¹ Cu and 0.9 kg ha⁻¹ Zn to dairy farmland are estimated for the median manure composition. Concentrations of lead (Pb), cadmium (Cd), and mercury (Hg) did not exceed 4.3, 0.4, and 0.05 mg kg⁻¹ (dry weight), respectively, in any manure sample. Correlation of manure Pb concentration to aluminum (Al), indicates that soil contamination of the manure accounts for most of the Pb.

ACKNOWLEDGMENTS

The authors thank Paul Sirois of Dairy One Analytical Services for providing dairy manure samples, Dr. Lucia Tyler for ICP–AES analyses, and E. Hare, P. Crowhurst, and T. Wood for assistance with the digestion and ICP–MS analysis. This research was supported in part by the Agricultural Ecosystems Project (Cornell University).