Composting vs. Vermicomposting: A Comparison of End Product Quality

Abstract

Composts and vermicomposts from a municipal composting plant in northwestern Patagonia, both having undergone a thermophilic phase, (with the vermicompost being inoculated with earthworms after the thermophilic stage) and a nonthermophilic backyard vermicompost were studied. Their effects on soil biological and biochemical properties and plant growth were evaluated in laboratory incubations and a greenhouse trial, using a degraded volcanic soil amended at rates of 20 and 40 g kg-1 of vermicompost or compost. Between the two municipal products, the vermicompost had significantly larger nutrient concentrations than the compost; when mixed with the soil, the vermicompost also had higher microbial populations size and activity, and produced increased ryegrass yields. Compared to the municipal compost, the backyard vermicompost had similar or higher nutrient concentrations but its effects on soil microbial biomass, soil microbial activity and ryegrass yields were lower. Our results suggest that no generalization can be made regarding the higher quality of vermicomposts vs. composts, because the product quality depends both on the original materials and the technology employed.