Canadian Forest Service Publications
Characterization of Canadian backyard composts: Chemical and spectroscopic analyses. 1998. Preston, C.M; Cade-Menun, B.J.; Sayer, B.G. Compost Science and Utilization 6(3): 53-66.
Issued by: Pacific Forestry Centre
Catalog ID: 5066
Despite the growing interest in backyard composting as a means to reduce residential refuse at source, there has been little study of its chemical nature and state of maturity. We obtained samples of mature compost from backyard sources in Newfoundland, Ontario and British Columbia, Canada, as well as raw input and immature compost from one BC municipal source. Chemical analysis indicated that composting was effective, proceeding with loss of C, decrease in C/N ratio, increase in pH to near neutrality, and high available N and P. Contents of heavy metals were low. Solution 31P nuclear magnetic resonance (NMR) spectroscopy of extracts showed a high proportion of orthophosphate P, indicating vigorous microbial activity and high P availability. Solid state 13C NMR with cross-polarization and magic-angle spinning (CPMAS NMR) of whole composts showed that decomposition proceeds to some extent with increasing ratio of alkyl to O-alkyl C, as observed in many studies of organic soils, forest floor and composts of low substrate quality. However, the backyard operations also produced much more peak broadening, and a marked tendency for increase of carboxyl C. These also indicate vigorous biological activity. The chemical and spectroscopic analyses confirm traditional knowledge of the efficacy of backyard composting, and suggest that it is a worthwhile object of research.