Evaluating the growth characteristics of lettuce in vermicompost and green waste compost

Vermicompost was produced from a green waste compost feedstock and assessed for its potential use in a high value horticultural market. Replicated plant growth trials were undertaken with lettuce using pure worm cast (vermicompost), green waste-derived compost and mixtures of the two, i.e. 50/50 (v/v) and 20/80 (v/v) of worm casts and green waste feedstock. Results showed that plant biomass production was optimal with a 20/80 (v/v) compost blend, whilst pure worm cast and green waste compost yielded poor growth. Leaf chlorophyll content indicated that pure worm cast inhibited plant growth and depressed N content, whereas plant grown with the other treatments contained similar amounts of chlorophyll. In general, the vermicomposting process did not result in an increased availability of nutrients or potentially toxic elements, the only exception being Zn.