Humic Substances as Indicator of Degradation Rate of Chernozems in South-Eastern Poland

Unfavourable quantitative and qualitative changes of soil organic matter result from degradation processes, such as water erosion connected with intense arable land use. In order to take adequate preventive action, the proper indicators of soil quality or degradation are urgently needed. In particular, tests considering the soil organic matter quality seem to be beneficial for soil monitoring. In this paper, we performed organic matter fractionation using the Tyurin and IHSS procedures on eight profiles of chernozemic soils (non-degraded, eroded, forest and accumulative soils). The study conducted confirmed the applicability of using humic and fulvic fractions in order to determine the pedogenesis processes and degradation rates of chernozemic soils. For example, the HA/FA ratio was higher in non-eroded and accumulative soils, compared with eroded or forest profiles. These findings were supported by statistical discrimination performed on the mid-infrared spectra of humic acids extracted from the selected profiles. Groups of samples were divided into classes depending on land usage or degradation rate. Considering the results, fractions of humic substances can be recommended as useful tools for the assessment of soil transformation.