Organic carbon and humic substances fractions in soil aggregates

Abstract

The aim of this study was to determine properties of organic matter contributing in formation of soil aggregates. Soil samples were collected from the plough layer from three variants (control, manure, NPK) of the long-term (55years) static fertilizer experiment. Soil aggregates were separated from soil samples by a new method using methanol-water solutions. The stability of all aggregates decreased with increase of water content in solution. Most water-resistant aggregates were in the soil fertilized with manure and least in the soil fertilized with NPK. Organic carbon content in aggregates presented highest in manured soil. Organic carbon content was lower, and the sum of humic and fulvic acids carbon was higher in aggregates separated with methanol solutions than those in aggregates separated with water.