BOOK OF ABSTRACTS 243 IHSS&IWA26 / BRNO / CZECHIA / 23–28 August 2026 Hall A Poster Session / Environment, Agriculture, and Forestry P4.17 Oxitop-IDS Respirometry as a Tool for Assessing the Effects of soil Conditioners on Microbial Activity of Soil Michal Kalina1, Barbora Hlaváčková1, Markéta Švecová1, Martin Súkeník, Miloslav Pekař1 1 Brno University of Technology, Faculty of Chemistry, Purkyňova 464/118, 612 00, Brno, Czech Republic, kalina-m@fch.vut.cz Soil respiration is a widely used indicator of microbial activity and soil organic matter dynamics, reflecting both intrinsic biochemical processes and the effects of external disturbances or soil amendments. This contribution presents an optimised approach for measuring soil respiration using the OxiTop®-IDS respirometric system according to DIN ISO 16072, with particular emphasis on improving experimental sensitivity, reproducibility and comparability of the obtained data. Key incubation parameters, including soil moisture, temperature, sample mass and incubation time, were systematically optimised under controlled laboratory conditions. The results confirmed that soil respiration is strongly dependent on incubation conditions, particularly water-holding capacity and temperature, highlighting the need for strict experimental control. The optimised method was subsequently applied to evaluate the effects of selected soil conditioners and microbial amendments on respiration kinetics in a model experiment. Tested materials included raw, separately pre-cultivated bacterial biomass suspended in PBS (strain Azotobacter vinelandii CCM 289), a representative biochar sample (Novoterra, Novocarbo, Germany), alginate hydrogels with or without biochar and bacterial cells, and lyophilised alginate gels with or without biochar and incorporated bacterial cells. Experiments were performed under defined conditions using an artificial soil mixture (composed of garden substrate, sand and perlite in a volume ratio of 1:3:1). Automated carbon dioxide monitoring enabled continuous quantification of microbial responses to organic matter inputs and soil amendments. The data were processed using the kinetic approach described by Kolář et al. [1,2], allowing the calculation of parameters characterising the rate and extent of organic matter mineralisation, including BODmax and the mineralisation rate constant k. Significant differences in respiration kinetics were observed among soils subjected to different soil conditioner treatments; the application of biochar, alginate hydrogels, soil rhizobacteria and their combinations led to measurable increases in respiration rates, indicating altered microbial activity and organic matter turnover. The results demonstrate that the optimised OxiTop®-IDS respirometric
RkJQdWJsaXNoZXIy NDA4Mjc=