Assessment of the structural-aggregate composition of podzolized chernozem under various agrogenic impacts and post-agrogenic state

V. Bulgakov¹, I. Gadzalo², V. Kropivnyi³, O. Demydenko⁴, I. Holovach¹, Ye. Ihnatiev⁵⁶, O. Trokhaniak¹ and J. Olt⁵*

¹National University of Life and Environmental Sciences of Ukraine, 15 Heroyiv Oborony Str., UA03041 Kyiv, Ukraine
²National Academy of Agrarian Sciences of Ukraine, 9 Mykhailo Omelyanovych-Pavlenko Str., UA01010 Kyiv, Ukraine
³Central Ukrainian National Technical University, University Ave., 8, UA25006 Kropivnitskyi, Kirovograd region, Ukraine
⁴Cherkasy State Agricultural Experimental Station National Scientific Centre, Institute of Agriculture of NAAS of Ukraine, 13 Dokuchaieva Str., Kholodnianske village, Cherkassy district, UA20731 Cherkassy region, Ukraine
⁵Estonian University of Life Sciences, Institute of Forestry and Engineering, 56 Kreutzwaldi Str., EE51006 Tartu, Estonia
⁶Dmytro Motornyi Tavria State Agrotechnological University, 66 Zhukovsky Str., UA69600 Zaporizhzhia, Ukraine
*Correspondence: jyri.olt@emu.ee

Abstract:

Identify the main patterns of transformation and establish normative parameters of changes in the structural and aggregate composition of low-humus podzolized chernozem (type of soil, known as ‘chernozem’ in Ukrainian, which translates to ‘black soil’) in the Central Forest-Steppe of Ukraine in the transition period to the no-till system and minimal tillage in the agrocenosis of 5-field grain generally accepted approaches to assessing soil structure and modern statistical methods of compiling information analysis data. The generally accepted research methods were used: field, laboratory, mathematical methods, comparative and computational. The study uses fractal comparative analysis, which is a sensitive tool for assessing the distribution of structural units and water-stable aggregates in the soil. Over the past 6 years, the experimental plots have been organized with a 5-field grain-row crop rotation using three different primary tillage systems: systematic plowing, surface tillage, and transitional tillage (minimal tillage on the background of systematic plowing six years ago). It was found that the structural-aggregate state of the 0–30 cm layer of Chernozem under surface tillage was in better condition in terms of aggregate water stability over the seasonal cycle and provided better conditions for further transition to the no-till system in crop rotation compared to surface tillage after systematic plowing. According to fractal indicators, the state of water-resistant structure in the spring is assessed as unstable, although the surface treatment of qualitative and quantitative indicators of water resistance is better compared to plowing. In the summer, a fractal assessment of the state of the waterproof structure showed that regardless of the method of tillage, its condition has deteriorated to a greater extent. Thus, the fractal dimension was at the level of D > 2, which indicates the edge of the unstable state of the waterproof structure, but the Hurst index was H ≤ 0, which indicates the process of destruction of waterproof aggregates. Based on the definitions, we can say that from the systematic application of surface tillage agrophysical condition of 0–30 cm layer of chernozem in terms of structural condition and water resistance of the structure was in better condition compared to plowing and transitional tillage, which should be regarded as the end of the transition period (6 years) before the application of the No-till system in unchanged design in 5-field crop rotation.

Key words:

fractal dimension, plowing, structural condition, surface treatment, water resistance