Inoculation of cattle manure with microbial agents increases efficiency and promotes maturity in composting.

In this study, fresh cattle manure was mixed with rice straw at a ratio of 10:1 in fresh weight and then composted in a self-built, aerated static composting box, whose dimension was 1 m × 0.8 m × 0.8 m with a volume of approximately 0.6 m3. To deal with the inconvenient and time-consuming problem of multiple stage inoculation, a single, one-time inoculation agent containing diverse microorganisms that are active at both the initial heating and thermophilic phases was developed. A total of 12 from 42 strains isolated from the none-inoculated Experiment 1 composting system were selected as microorganismal agents in Experiment 2 according to their species, prevalence and cultural temperature. 200 mL of each microorganism enrichment broth was mixed to the inoculation group at the beginning of composting. A total of 2400 mL of sterilize distilled water was added to the control group. The parameters of temperature, moisture, pH, C/N ratio, organic matter degradation, and germination index were investigated for both inoculation and control composting groups. Results showed that inoculation did not significantly shorten composting time. However, the pile temperature was increased with the maximum temperatures of 64.6 °C and 60.3 °C for the inoculation and control groups, respectively. The degradation of organic matter was accelerated (P < 0.05), and significantly higher GI value (P < 0.05) indicated that the maturity was promoted by the inoculation microorganism. This suggests that the final composting product would provide value as alternative source of nutrients for plants. Conclusively, we suggested a multiple microorganism inoculation method to increase the efficiency and promote maturity in cattle manure composting. © King Abdulaziz City for Science and Technology 2020.