THE INFLUENCE OF SHORT-LIVED LEGUME SWARDS AND STRAW ON SOIL HUMIC SUBSTANCES IN A CLAY LOAM CAMBISOL

摘要

The experiments were designed to estimate the effects of short-lived legume swards. Therefore, the mass of Trifolium pratense L., a mixture of Trifolium repens L. and Lolium multiflorum Lamk. and straw of Triticum aestivum L. were incorporated into the soil, and the effects of changes of soil humic substances and their quality in 0–25 cm soil layer were monitored in a clay loam Cambisol, in two years. In the first year, it was found that incorporation of T. repens and L. multiflorum mass increased the content of mobile humic acids, total humic acids and extractable humic substances (sum of humic and fulvic acids), compared with the respective values before the trial establishment. T. pratense mass increased only the content of mobile humic acids. Conditionally stable humic acid fractions were formed more intensively in the second year of legume mass and straw effect. The best quality of humus was observed using the mass of T. pratense, in combination with cereal straw. Based on our findings, we conclude that the mass of legume swards used as green manure influenced the increase of humic substances only for one year after incorporation. Increases of stable humic substances were determined using the mass of legume swards, in combination with cereal straw.