Selection of maturity indices for compost derived from grape pomace

Abstract

Compost quality is usually determined through chemical composition and sanitary parameters; however it is necessary to determine more precise maturity indices. The objective of this work was to identify sensitive properties to measure compost maturity using a novel approach based on quality indices. Nine mature compost piles were sampled and analyzed for extractable and total elements, NH4-N/NO3-N, electrical conductivity, C/N ratio, humic and fulvic fractions, hydrolytic enzyme activities, radish germination, respiration CO2 and microbiological parameters. The results indicated that humic acid: fulvic acid ratio, total bacteria count, and hydrolytic enzyme activities were sensitive parameters to define compost maturity and more specific tools to explain microbial activity and humification degree along the curing phase. The proposed model could be used to evaluate compost maturity with good reliability.