The effect of blood powder application on some biochemical properties of sawdust during vermicomposting

This study aimed to recycle sawdust and blood powder using Eisenia foetida earthworm and investigate some biochemical changes of these waste materials during vermicomposting. Blood powder was mixed with sawdust in proportions of 0, 5 and 10% and the mixture was allowed to pass through earthworm guts for four months. At intervals of 1, 2, 3, 4, 6, 8, 12 and 16 weeks, the biological activity (i.e. basal respiration), pH, EC, total organic carbon, total nitrogen and C:N ratio were determined. The results showed that the period of time, the concentration of blood powder and the interaction between these two significantly affected all parameters. As the incubation time increases, the cumulative amount of mineralized carbon, the total nitrogen and EC increase in all vermicompost treatments whereas organic carbon, C:N ratio and pH decreased. Adding blood powder to sawdust bed resulted in an increase in carbon mineralization rate, EC and total nitrogen while pH, organic carbon and C: N ratio decreased. At the end of incubation time, the treatment of sawdust with 10 % blood powder resulted in the highest amount of released CO2 (142.1 µg C g-1), EC (3.7 dS m-1) and total nitrogen (2.24 %) and the lowest amount of pH (6.6), organic carbon (22.5 %) and C: N ratio (12.4). According to the results, the process of vermicomposting can be used as a safe method for the disposal of sawdust and blood powder.