The studies were conducted to investigate the impact of agronomic technologies (traditional, differentiated, minimum, and direct sowing), which differ in the method of primary tillage and plant protection system, on the qualitative and quantitative characteristics of humus in typical chernozem. The study focused on a powerful, heavy-loamy typical chernozem. The soil samples were analyzed for their humus content, total nitrogen, and the fractional-group composition of humus using the Tyurin method, as modified by Ponomareva and Plotnikova. The use of technologies based on minimizing soil tillage contributes to the accumulation of C in the 0…10 cm layer, which was 3.10–3.14 %. The content of humic acids bound to calcium (HA‑2) increased from 37.08 % in the traditional technology to 34.21…38.44 % in the direct sowing and differentiated technology, and to 41.47 % in the minimum tillage technology. The change in the content of humic acids, free and bound to mobile half-oxides (HA‑1), in the 0…10 cm and 10…20 cm soil layers was 0.43…0.70 % of С, and the change in the content of humic acids bound to clay minerals (HA‑3) was 0.30…2.20 % of C, in favor of the 0…10 cm layer. Traditional technology contributed to the growth of HC‑1 by 0.26…0.70 % of С, while the minimum HC‑3 contained more by 0.29…2.15 % of С, in relation to other technologies. It was noted that the optical density of humic acids in the 0…10 cm layer exceeded by 0.02–0.04 in technologies focused on minimizing soil processing. The study of the first stage of humification, which shows the intensity of the process of humic acids formation, demonstrated its activation with depth when using traditional technology, while this process weakened or faded when processing was minimized. The analysis of the second stage of humification, which characterizes the process of humate formation, showed its significant intensification in the 10…20 cm layer, which indicates the polymerization of humus structures, regardless of the applied agricultural technology.
E. V. Dubovik (Wed,) studied this question.