Assessment of the possibility of humic acid extraction from vermicompost with urea

Abstract

The aim of this study was to introduce new possible extractants for humic acid and determination of qualitative and quantitative characteristics of humic acid that were extracted with the new extractants. In the present study, vermicompost, a plant growth promoting biofertilizer containing many humic substances, was used as initial substrate for humic acid extraction. In order to determine the optimal concentration, urea was used in three concentration levels (0.1, 0.5 and 1 mol L-1). In this regard, urea 0.1 M was incapable of extracting humic acid within 24 h, and the maximum amount of humic acid was extracted with 0.5 M urea. Thereafter, to ensure the nature of humic acid extracted with urea and its quantitative characteristics, indices such as elemental analysis, acidic functional groups content and total hydroxyls content were determined and additional spectrophotometric measurements carried out as well. Further research could be conducted with these extractants to determine the nature of extracted humic acid. Finally, more research on the use of urea as a new extractant is recommended.