INFLUENCE OF PARTICLE SIZE DISTRIBUTION OF SOIL ON THE QUANTITY AND QUALITY OF SOIL ORGANIC MATTER

Abstract

Influence of particle size distribution of soil on the carbon and nitrogen contents and fractional composition of humus substances was studied in different soil types (Eutric Fluvisol, Haplic Chernozem, Haplic Luvisol, Eutric Regosol). Experiment includes the soils of forest ecosystem (control) and agro-ecosystem with 4 crop rotations. Particle size distribution of the soil influenced the content and quality of soil organic matter. The higher proportion of smaller fraction (<0.001 mm) was, the higher was content of soil organic matter (r = 0.794; P < 0.01) and subject to smaller changes (r = 0.551; P < 0.05). Higher content of size fraction <0.001 mm supported higher stability of humus substances (r = -0.755; P < 0.01) and humic acids (r = -0.533; P < 0.05), and the humic acids bound with mineral components and stabile R₂O₃ were dominated. Higher proportion of humic acids bound with mineral components and stabile R₂O₃ was in the size fraction of clay (0.001 mm), but fulvic acids bound with the mobile R₂O₃ and free was in fine sand size fraction (0.05-0.25 mm). Higher content of organic matter was in natural ecosystem, but its quality was better in arable land.