Trace elemental characterization of composted poultry manure

Aerobically composted poultry manure was comprehensively characterized with respect to elemental content. Total, water-extractable and 1 nitric-acid-extractable concentrations of 21 trace, minor and major elements: Al, Ba, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, P, Pb, Rb, S, Sr, Ti, V and Zn, were determined in manure slurry composted with barley/oat straw or sphagnum peat moss bulking agents. Levels originated predominantly from the manure and total concentrations in composts, expressed as mg/kg on a dry basis, ranged from 0.2 for Cd, 2–5 for Cr, Mo, Ni, Pb, Ti and V, to 37 000 for Ca. Extractable concentrations varied with extractant and element from a low of 2% of total for Ba with water to 100% for most elements with acid. Nitric acid facilitated quantitative leaching of virtually every element tested with the exception of Mo. Cadmium, Na and Rb were fairly completely leached out with both water and acid. The effect of composting time for four elements with sufficient data, Cu, Fe, Mn and Zn, suggested a hint of immobilization of Mn and Zn with respect to water extraction and of Cu and Fe with respect to acid extraction and increased lability of Mn and Zn to acid extraction after composting.