BOOK OF ABSTRACTS 189 IHSS&IWA26 / BRNO / CZECHIA / 23–28 August 2026 Hall A Poster Session / Soil Organic Matter, Caustobiolites, and Biochar P2.1 The Impact of Soil Tillage System on the Relationships Between Humic Substances and Soil Aggregate Fractions Erika Balontayová1, Štefan Koco2, Gabriela Barančíková2, Bożena Dębska3 Slovak University of Agriculture in Nitra, Institute of Agrochemistry and Soil Science, Tr. A. Hlinku 2, 949 76 Nitra, Slovakia e-mail: Erika.Balontayova@uniag.sk NAFC - Department of Soil Science and Soil Protection, Regional Office Prešov, Malý Šariš 221, 080 01 Prešov, Slovakia e-mail: stefan.koco@nppc.sk; gabriela.barancikova@nppc.sk Bydgoszcz University of Science and Technology, Department of Biogeochemistry, Soil Science and Drainage, 6/8 Bernardyska Street, 85029 Bydgoszcz, Poland e-mail: Bozena. Debska@pbs.edu.pl Humus substances (HS) play an important role in the formation of soil aggregates. Soil type is the primary factor that determines the amount and quality of HS [1]. Soil tillage significantly influences the fractional composition of soil aggregates [2]. A combination of these factors (soil type and soil tillage) changes the relationships between HS and soil aggregates. The evaluation of the impact of the soil tillage system (STS) should be made to a depth higher than that to which mechanical operation is done [3]. The study included four soils (Mollic Fluvisol, MF; Haplic Chernozem, HC; Haplic Luvisol, HL; Eutric Regosol, ER), two STS (conventional, CT; reduced, RT), three crop proportions, and 7 repetitions. Experimental localities were located in the Danubian Lowland of central Europe. In soil samples, taken from a depth up <0.3 m, the group composition of HS (humic acids, HA; fulvic acids, FA), ratio of humic acids and fulvic acids (HA/FA), degree of humification (Dhum), colour quotients of HS and HA (QHS465/650, QHA465/650) and fraction composition of wet-sieved macroaggregates (WSA) as follows: >5; 3 – 5; 2 – 3; 1 – 2; 0.5 – 1; 0.25 – 0.5 mm, were determined. The obtained data were subjected to Principal Component Analysis to identify the relationship between HS and WSA, and to a Pearson correlation analysis (P<0.05). In the CT, differences among soil types are blurring, and the impact of HS quantity and quality on WSA is dominant. The most pronounced factor reflects the stability of HS and the proportions of the aggregate fractions (PC1 + PC2 ≈ 49.66 + 19.32 = 68.98%). At a higher proportion of HA and a higher ratio of HA/FA, the larger WSA (>3 mm) (dominantly in MF and HC) were dominant, and in the contrast at a higher proportion of FA, the smaller WSA (<0.5 mm) (dominantly in HL and ER) together with a lower condensation (QHS465/650, QHA465/650) dominated.
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