Carbon- and nitrogen-containing compounds in composted urban refuses

• Published in: Bioresource technology 1993, Vol.45 (2), p.115-121
• Main Authors: González-Prieto, S.J., Carballas, M., Villar, M.C., Beloso, M.C., Cabaneiro, A., Carballas, T.
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Compost; Fundamental and applied biological sciences. Psychology; fundamental components; General agronomy. Plant production; humic compounds; municipal solid wastes; organic matter; organic N; organic N forms; organic wastes; Other nutrients. Amendments. Solid and liquid wastes. Sludges and slurries; Soil-plant relationships. Soil fertility. Fertilization. Amendments
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/0960-8524(93)90099-W

The composition of the organic matter of four composted urban refuses (one of them amended with CaCO 3 in the composting process) from Spanish industrial composting plants was studied. Fundamental components and C-bearing compounds (humic substances) were assessed by classical fractionation methods; N-bearing compounds were determined by acid step-wise hydrolyses. Cellulose and hemicelluloses largely predominated over lignin, which was the second important component, followed by water-soluble compounds, the content of lipids being very low. Water-soluble compounds represented 3–14% of the organic C. Alkali-soluble compounds were quite low since humic compounds (humic and fulvic acids) only represented about 17% of the organic C (24% in the amended compost); humic acids predominated over fulvic acids, the most polymerized compounds being higher than the less polymerized ones. The predominant fraction (about 70% of the organic C) was the insoluble one which comprised unhumified compounds, insolubilizable humin, microbial humin (1·4–9·0% of the organic C) and residual humin (20–40% of the organic C). The extraction percentage was very low whereas the degree of humification was close to 50%. About 85% of the organic N was hydrolysable. Hydrolysable unidentified-N was the predominant organic N form, followed by α-aminoacid-N. NH 4 +-N from organic compounds and hexosamine-N were very small and amide-N was not detectable. According to the percentage of humification the four composted refuses were stabilized materials.