The chemical characteristics of ashes from cattle, swine and poultry manure

Abstract

Animal manure is waste that contains large amounts of fertilizer resources. Incineration technology is effective in decreasing the volume of animal manure and concentrating the nutrients. In this study, the nutrient concentration and chemical compounds of several types of animal manure ash were examined to promote their recycling for agriculture. The nutrient concentration of manure ash was dependent on the reduction rate of solid materials by incineration. The phosphorus (P) and potassium (K) of cattle and layer manure were not concentrated greatly because of high silicon (Si) and calcium (Ca) concentrations, respectively. On the other hand, the P concentration of swine manure and broiler litter was increased to 10.1–12.0 % (3.6–4.6 times compared with original materials), equivalent to that of phosphate rock used as fertilizer material. The K concentration of broiler litter ash (16.1 %) was highest of all. The phosphate compounds of cattle and swine manure ashes were determined as Ca₉Fe(PO₄)₇ or Ca₉MgK(PO₄)₇. Hydroxyapatite (Ca₅(PO₄)₃(OH)) was detected in layer manure and broiler litter ashes. By acid treatment of ash, P and K availability of the fertilizer made from layer manure ash (33 % of materials) was equivalent to that of conventional chemical fertilizer.