Humus state and effective fertility of podzo­lized chornozem under different tillage in agrocenosis

Abstract

Goal. To determine the patterns of formation of the humus state of podzolized chornozem under the influence of systematic plowing, surface tillage (10–12 cm) for 10 years (from 2016), the transition to No-till after plowing and surface tillage of the latter for 5 years, as well as the level of realization of potential fertility by the yield of grain units in 5-field grain rotation. Methods. Field (to establish the influence of different cultivation systems on the content of organic matter in podzolized chornozem), analytical (to determine the humus content by the Tiurin method), calculation (to calculate the humus balance in the 5-field crop rotation), and statistical dispersion analysis using the Statistica 10 computer program. Results. The study was conducted in 2021–2025 on the experimental basis of the Cherkasy State Agricultural Research Station of the National Scientific Centre «Institute of Agriculture of NAAS». The soil cover of the field was podzolized chornozem, strongly graded, low-humus, medium-carbonaceous on carbonate loess. During plowing, the level of natural soil fertility decreased, and the mineralization process intensified, but the potential fertility of the soil contained a significant part of the resource of effective fertility, which exceeded the required level for the implementation of the agricultural potential of the podzolized chornozem in agrocenosis. With surface tillage, the level of mineralization decreased by 15–20%, which limited the excess resource of effective fertility to obtain equivalent productivity for plowing. Due to the strengthening of the process of depositing organic matter into humus and optimizing the level of mineralization with humification, the natural fertility of chornozem was restored. Potential fertility was improved by natural efficient fertility with an optimized resource. In no-till cultivation, an active deposit of organic matter into humus occurred, which ensured the reproduction of natural fertility. Potential fertility had a 15–19% lower level of effective fertility compared to plowing. This was the «preservative» effect of the No-till system at the initial stage of implementation, which led to a decrease in the yield of grain units in the agrocenosis of the 5-field crop rotation in the conditions of the central part of the Forest-Steppe of Ukraine. Conclusions. Under these conditions, the realization of the effective fertility of podzolized chornozem in the 5-field crop rotation by the yield of grain units using systematic plowing and surface tillage was at the level of 4.67–4.82 t/ha. For No-till cultivation, the implementation of the agricultural potential of the yield of grain units decreased by 12.7–13.5%. In the case of switching to No-till after plowing in the initial period, the agricultural potential of their output decreased by 13.5%, and in the case of switching to No-till after surface tillage, by 9.9%, which was 1.35 times more effective. In the initial period, the level of effective fertility by the yield of grain units decreased by 12.7–13.5% compared to plowing and surface tillage. With the use of the latter for 10 years, the level of effective fertility was 3.1% lower than for plowing.