Comparison of humus balance methods in relation with yields of monoculture spring barley

Long term stationary field experiments with continuous spring barley were conducted in the maize-growing region on heavy gleic fluvisol from 1974 to 2002. Two variants of straw management (straw harvested and incorporated into soil), two variants of soil tillage (conventional plough tillage to 0.22 m, shallow disc tillage to 0.12-0.15 m) and three variants of fertilization (30, 60 and 90 kg. N ha-1) were studied. The results of organic matter balance in the examinated period according to particular methods were related to trends of real humus content which is presented in Cox in particular experiment variants. The examinated method by LEITHOLD et al. (1997), used in model Repro, answers most accurate in given conditions according to hypothesys defined in scientific literature. On the base of this result we can confirm significancy of the result. Other verification of method is appropriate for its using in real conditions in context of agricultural sustainability assesment.