VERMICOMPOSTING OF COFFEE PULP USING THE EARTHWORM EISENIA-FETIDA - EFFECTS ON C AND N CONTENTS AND THE AVAILABILITY OF NUTRIENTS

In Colombia, more than 1 million tons of coffee pulp are produced ever y year. Its transformation into compost by means of turned piles has l ed to a final product with poor physical and chemical characteristics and vermicomposting has been suggested as an alternative method of tra nsforming these wastes into a useful organic fertilizer. The ability o f the earthworm Eisenia fetida to transform coffee pulp into a valuabl e compost was evaluated. The influence of bed depth and time on differ ent C fractions, N content and availability of nutrients was studied. The results showed that the C and N contents were not affected by the depth of the bed, whereas time affected both. An increase in the fract ionation ratio, determined by calculating the C in the fraction smalle r than 100 mu m as a percentage of C in the samples as a whole, and lo w values of humic-like substances were recorded during vermicomposting . After ingestion of the pulp by the earthworms, an increase in availa ble P, Ca, and Mg but a decrease in K were detected.