respiration rate of composting pig manure

• Published in: Compost science & utilization Vol. 12; no. 2; pp. 119 - 129
• Main Authors: Cronje, A.L, Turner, C, Williams, A.G, Barker, A.J, Guy, S
• Format: Journal Article
• Language: English
• Published: Emmaus,PA Taylor & Francis 01.03.2004; JG Press; Taylor & Francis Ltd
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Other nutrients. Amendments. Solid and liquid wastes. Sludges and slurries; Soil-plant relationships. Soil fertility. Fertilization. Amendments; Pig manure; Compost; Composting; Respiration; Waste reuse
• ISSN: 1065-657X; 2326-2397
• DOI: 10.1080/1065657X.2004.10702170

The rate at which oxygen is consumed during composting is a measure of aerobic microbial activity and is linked to the rate of organic material decomposition. The rate of loss in mass is a function of the mass of the degradable organic fraction and is related to oxygen uptake rate by the reaction rate coefficient, k. The decomposition of a pig manure and straw mix was investigated at temperatures between 10°C and 70°C using respirometric techniques. The oxygen concentrations in the reactor were measured continuously for about 4 days and then converted to hourly oxygen uptake rates for each incubation temperature, T. The specific oxygen uptake rate was used to calculate the reaction rate coefficient at T, k T , for the observed fast and slow stages of decomposition. The effect of the environmental factors was taken into account using a multiplicative approach and a relationship, which expressed k T for each stage as a function of T, was formulated. The maximum measured rate of activity occurred during the fast stage at 60°C where k T fast = 0.31 day −1 . Activity increased exponentially with the temperature in both stages up to about 60°C. At higher temperatures, the activity slowed but most noticeably in the fast stage. The dependence of k T on T during each stage was described by a double power expression, which predicted that activity would cease around 73°C. The relationships may be used to improve a compost model that is based on a first order reaction rate kinetics for the decomposition of organic material.