The potential of seaweed biochar and fly ash amendments in enhancing vermi-degradation and the fertilizer value of cow manure, wastepaper-based vermicompost

This study evaluated the potential of amending cow manure (CM) based vermicompost with fly ash (FA) and seaweed biochar (Bio) on vermidegradation, nutrient release and early crop growth. All treatments, except CM + fly ash, resulted in a C/N ratio below 20, indicating a mature compost. The CM + Biochar treatment had the highest Olsen-P of 274.75 mg/kg whilst the CM + Fly ash treatment had the lowest concentration of 239.13 mg/kg. Only Zn showed a consistent increasing trend of 51.5 %, 45.6 %, 53.6 %, and 47.8 % for the CM + fly ash, CM + FA + Bio, CM + Bio, and CM treatments, respectively. For crop germination, the CM + fly ash compost needs to be substituted at 25 % in cocopeat, whilst 50 % substitution is suitable for seedling development. Future studies need to evaluate the potential of removing salts from seaweed-biochar, and the field soil application of seaweed and fly ash amended vermicomposts.