Physico-chemical and microbiological study during conventional composting using different rates of rice straw and cattle manure mixture

Decomposition of rice straw and cattle manure using conventional composting were affected by factors including physico-chemical properties and microbiological activity. In this study, physico-chemical characteristics and microbial population were monitored to understand the changes involved when different amounts of rice straw were composted with cattle manure. Three combinations of rice straw with cattle manure at the rate of 120 kg:80 kg for B1, 140 kg:80 kg for B2 and 160 kg:80 kg for B3 and composted for 60 days were studied. Temperature, pH, electrical conductivity (EC), moisture and C/N were measured. Diversity of mesophilic bacteria and fungi were monitored using plate count technique. Highest temperature of compost was observed in B1 and B2 reaching 65 °C which dropped gradually towards ambient temperature. C/N ratio dropped rapidly during the first two weeks for B1 and B2 while the ratio of B3 decreased slowly. Population of microorganisms showed higher number for mesophilic bacteria ranging from 8.3 – 9.0 log CFU/mL compared to fungi ranging from 7.5 – 8.5 log CFU/mL during composting. Correlating physicochemical analysis with microorganism diversity revealed that the microorganisms required an optimum range of substrate for growth in order to decompose organic materials successfully.