Quantity and quality of humic acids extracted from sandy soils fertilized with vermicomposts

Abstract

A significant increase in the amount of produced organic waste made it necessary to work out different methods of their utilization, including the vermicomposting process. Vermicomposts were produced with the Eisenia fetida Sav. on the basis of waste activated sludge with
the addition of mixed sawdust and waste from a meat processing factory. Vermicomposts were applied in a pot experiment on two soil materials: weakly loamy sand and heavy loamy sand. The Lolium multiflorum Lam. was the tested plants harvested eight times during two vegetation periods. After two years of experiment from total amount of carbon introduced into pots taken as 100%, in slightly sand there was left 56.0% and in loamy sand – 59.4%. The quantity of organic carbon compounds extracted from the soil materials with 0.1 mol NaOH dm^-3 in the 1^st fraction was 70.2% and in the 2^nd 29.8% of total carbon in which 81.4 and 55.2% were in humic acid, respectively. In the extracts from heavy loamy sand these values were 68.3 and 31.7%, including 84.2% and 57.2% in humic acids of total extracted carbon, respectively.