Humus status of chernozem soils formed under deep hydrogen release and different humidification conditions

Purpose of the study: to reveal changes in some humus characteristics in chernozems under the influence of of two factors, specifically, humidification and the flow of endogenous hydrogen. Place and time of the study. Soil sampling and hydromenty were carried out on the territory of the Gryazinsky district of the Lipetsk region (Krivoborgsko-Saltykovsky trough, the territory with leached chernozems) and on the territory of the Oktyabrsky district of the Voronezh region (Khopersky deep fault, the territory with ordinary chernozems) in June 2017. Methods. The molecular hydrogen content was measured directly in the field with a portable hydrogen gas analyzer VG-3B. The total soil organic carbon (SOM) content was determined by the Tyurin method, and pH was measured potentiometrically. To assess the SOM composition, an alkaline pyrophosphate extraction was used. The luminance values of soil samples were determined using the CIELAB international chromaticity system and the LRV system on the Nix Color Sensor spectrocolorimeter. Results. The study showed that under the influence of hydrogen flow in different humidification regions, the effect of these two factors was different. Tthe establishment of the reductive regime, signs of podzolization and gleing in the morphological profile, acidification of the soil bulk and brightening of the upper humus horizon were found to be common features between the soils of these regions. However, the effect of such active reducing agent as hydrogen on the SOM and qualitative composition in these regions varied greatly. In the drier region with ordinary chernozems, SOM accumulated in hydrogen relief depressions (from 2.4 to 5.4%), and due to their sharp predominance (three times, sometimes four times) in SOM composition and predominance in the soil profiles, fulvic acids determined a sharp increase in soil acidity. The leached chernozems, on the contrary, manifested a significant SOM loss (from 3.9 to 2.2%), with humic acids predominating in SOM composition. This effect was most likely associated with the removal of more mobile SOM components outside the soil profile in the more humic climate of the Lipetsk region.