A study on the variations of temperature, moisture, pH and carbon to nitrogen ratio in producing compost by stack method

Considering the importance of chemical and physical parameters such as temperature, moisture, pH and carbon to nitrogen (C:N) ratio in producing compost, the purpose of this study was aimed to evaluate these parameters in producing compost by stack method.

This descriptive study was carried out on municipal solid waste generated in Kashan during a 63-day period from Oct 3 to Dec 4, 2010. Compost samples were taken from the top one-third, the center and also the bottom of the compost pile and mixed; the compost pile was aerated (if necessary). Thereafter, samples were analyzed for carbon and nitrogen content using Fourti method.

The initial temperature of the compost pile was 38°C and then increased to 65°C at the 9th day, and reached to 26°C at the last day of composting. The moisture at the beginning of the process was 67.5%, increased to 73% at the 5th day and decreased to 38% at the last day. The initial pH of the compost was 5.5, increased during the compost process, and reached an optimal value of 7.7 at the end of the process. The C:N ratio at the beginning of the process was 35:1 and in mature compost decreased to 12.5:1.

Presence of actinomycetes and the dark-brown color of the prepared compost on the 63rd day of composting indicate that the compost meets the required standards. Consequently, the implementation of this method is suitable for tropical cities like Kashan.