Transport of Metals (Al, Fe) and Trace Elements (Cu, Mo, Ni, and Zn) through Intact Soil Cores Amended with Fresh or Composted Beef Cattle Manure for Nine Years

Abstract

ABSTRACT Composting of feedlot cattle (Bos Taurus) manure may enhance metal and trace element accumulation and transport through the soil because these elements are concentrated in manure during composting. Little research has been conducted on comparing transport of metals (Al, Fe) and trace elements (Ni, Cu, Mo, Zn) through soil amended with composted manure (CM) versus fresh feedlot manure (FM) stockpiled for up to two months. Our objective was to determine if the transport of six selected chemicals (Al, Fe, Ni, Cu, Zn, Mo) was affected by the composting of cattle manure applied annually at 77 Mg ha−1 dry wt. for nine years to a clay loam soil. Intact soil cores were taken from a field experiment in the spring of 2007. Deionized water was applied to the soil cores in the laboratory under steady-state (4.9 cm d−1) and unsaturated conditions. The chemical concentrations were measured in the effluent and breakthrough curves and cumulative mass loss curves obtained. Flow-weighted mean concentrations (FWMC) and mass loss of Al, Fe, Ni, Mo, and Cu, recovery of total applied Al, and maximum concentrations of Fe and Mo were significantly (P ≤ 0.05) greater for CM compared to FM. Although greater chemical concentrations in amendments and soil for CM than FM may partially explain greater transport under CM, we believe that greater unsaturated hydraulic conductivity at 7 mBar for CM was a more important factor.