Vermicomposting, waste recycling and plant growth

Vermicomposting has been proposed as a sustainable technique for managing various types of organic wastes. The aims of this study were to test the feasibility of vermicomposting two of Canterbury’s problematic wastes (organic municipal waste and the used animal bedding) and to evaluate the vermicompost generated from them for use in horticultural production. The research first examined how changes in waste proportions and types affected earthworm growth and reproduction. Vermicompost quality in terms of its nutrient and agronomic values was then considered, through the use of a series of pot experiments with Pak Choi plants. These experiments investigated influencing factors such as the type of medium, source of vermicompost, application rate, application method, processing method and chemical fertiliser addition on plant growth. The results of the vermicomposting experiments showed that the two waste streams could be a valuable food source for earthworms, and it found that the ideal combination in terms of earthworm growth and reproduction and final vermicompost quality was a mix of 80% fresh shredded waste and 20% used animal bedding. The vermicompost produced from this mix generally had good agronomic value, but a low nitrogen content. Coir had high vermicompost use efficiency, and plants grown in coir with a 10% vermicompost addition grew as well as plants in a standard potting mix. Mixing chemical fertiliser and vermicompost together with coir led to further improvements in plant growth, compared with the use of vermicompost alone. These results demonstrated that it is feasible to recycle the two problematic wastes by vermicomposting, and that the vermicompost produced is beneficial as a plant fertiliser. Coir could be a promising material for use in horticultural production when combined with vermicompost. However, further research is required to investigate ways of using these resources in the most efficient manner.