Managing Global Resources for a Secure Future

               Abstract

Broiler litter ash (BLA), a byproduct of the incineration of broiler litter for electricity generation, contains high levels of phosphorus (P), copper (Cu), manganese (Mn), and zinc (Zn), which are rendered less soluble by incineration. A two-year field study was conducted to determine uptake and translocation of P, Cu, Mn, and Zn by soybean [Glycine max (L.) Merr.] grown on a low P soil (Rumford silt loam coarse-loamy, siliceous, thermic typic Hapludults) amended with BLA or superphosphate at 56, 112, and 224 kg P ha^-1. Plants were harvested at the early pod stage, and leaves, stems, pods, and roots were separated. Yield increased with increasing rate of P application but was not significantly affected by P source. Tissue P concentration decreased in the order pod > leaf > stem > root, while Cu, Mn, and Zn concentrations were highest in the leaf, followed by the pod, stem, and root.  Averaged over plant parts, tissue P concentration was 8% higher when superphosphate fertilizer was used compared with BLA, but there were no significant differences in tissue Cu, Mn, and Zn concentrations between the two P sources. Concentrations of P, Cu, Mn, and Zn in soybean leaves were 2486, 8.2, 195, and 72 mg kg^-1, respectively. Leaf concentrations of Mn and Zn were within the ranges considered sufficient for soybean leaves before pod set, but P and Cu were slightly lower. The comparatively low level of leaf P observed in this study may have resulted from the fact that the leaves were collected at the early pod stage instead of before pod set. The slight differences in tissue P, Cu, Mn, and Zn concentrations observed between the two P fertilizer sources in this study suggests that BLA could be used as an inexpensive P fertilizer for soybeans on low P soils.