Humic acids (HA) are widely used in agriculture because of their capability as chelator, organic matter, and soil improver and growth promoter. However, their isolation differs in terms of origin or source because of wetting and solubilisation factors. This study was conducted to determine extraction period for HA from organic sources. Standard procedures were used to extract HA from pressmud (PM) and vermicompost (VC) at different extraction periods of 4, 8, 12, 16, 20 and 24 hours and fractionation periods (3, 6, 9, 12, 15, 18, 21& 24 hrs). At the end of each extraction period, samples were centrifuged, followed by fractionation and purification. HA yield at different extraction periods was determined using standard procedures. The relationship between extraction period and HA yield was quadratic. Extraction and fraction period for PM & VC was 24 hours and purification (done in 1 h) using distilled water was effective in removing impurities. HA from PM and VC can be extracted and fractionated in 24 hours and purification can be done in one hour. | Influence of different extraction and fractionation periods on humic acid yield derived from pressmud and vermicompost
