Relationship between Compost Stability and Extractable Organic Carbon

• Published in: Journal of environmental quality Vol. 31; no. 4; pp. 1323 - 1328
• Main Authors: Wu, L., Ma, L.Q.
• Format: Journal Article
• Language: English
• Published: Madison American Society of Agronomy, Crop Science Society of America, Soil Science Society 01.07.2002; Crop Science Society of America; American Society of Agronomy
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Carbon - chemistry; Carbon - isolation & purification; Carbon Dioxide - analysis; Conservation of Natural Resources; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Humic Substances - chemistry; Other nutrients. Amendments. Solid and liquid wastes. Sludges and slurries; Sodium Hydroxide - analysis; Soil Pollutants - analysis; Soil-plant relationships. Soil fertility. Fertilization. Amendments; Volatilization; Water; Organic carbon; Compost; Stability; Waste treatment; Extraction process; Carbon dioxide; Humification; Mass absorption coefficient; Fulvic acid; Sewage sludge; Humic acid
• ISSN: 0047-2425; 1537-2537
• DOI: 10.2134/jeq2002.1323

ABSTRACT Establishing a simple yet reliable compost stability test is essential for a better compost quality control and utilization efficiency. The objective of this study was to examine the relationship between extractable organic carbon (OC) and compost stability based on 18 compost samples from five composting facilities. The compost samples were extracted sequentially with water for 2 h [water(2h)] and 0.1 M NaOH for 2 and 24 h [NaOH(2h) and NaOH(24h), respectively]. The extractable OC was further separated into fulvic acid (FA) and humic acid (HA) fractions by adjusting the pH to <2. The mass specific absorbance (MSA) of OC in the six fractions was measured. Compost stability was estimated with a CO2 evolution method. The extractable OC concentration was influenced by the total volatile solids and decreased with curing time for compost with a high level of extractable OC. The OC levels in each fraction were significantly correlated (p < 0.05) to each other except for the water(2h)–extractable HA. In addition, all the FA and HA fractions except for water(2h)–extractable HA were highly (P < 0.01) and linearly correlated to CO2 evolution, but multiple regression showed that NaOH(24h)–extractable OC was insignificant for CO2 evolution. The relatively high slope of NaOH(2h)–extractable FA versus CO2 evolution suggests that this fraction may contribute the most to compost CO2 evolution. The water(2h)– and/or NaOH(2h)–extractable FA tests are recommended for measuring compost stability because of their high correlation with CO2 evolution. This estimation can be obtained through a simple photometric method covering a wide range of carbon concentrations up to 4000 mg L−1