1st International Conference of Soil and Agriculture:
TOWARDS SOIL SUSTAINABILITY
11–13 June 2024 • Lublin–Nałęczów, Poland

https://doi.org/10.24326/ICSA1.1.07
Published online: 4 October 2024

Soil subhorizon Ofh (organic fermentative-humic) as
a ‘natural sponge’ of selected trace elements
Agnieszka Sołtys*, Sabina Dołęgowska

Institute of Chemistry, Jan Kochanowski University, Uniwersytecka 7, 25-406 Kielce, Poland
* Corresponding author:

Abstract
Geoindicators are used to identify geological processes and to assess changes in the environment and the effects of their impacts. They include abiotic elements of the environment, such as, sediments, groundwater or topsoil. In a temperate climate zone, the upper part of the forest soil forms the organic O horizon. This horizon is made up of subhorizons, including the organic fermentative-humic subhorizon (Ofh), which resembles a tobacco mat. The specific structure makes the subhorizon Ofh a kind of ‘natural sponge’, especially in relation to selected trace elements, such as Cd, Hg, Pb, Zn, which can in fact make it a potential geoindicator with regard to these elements. The main objectives of this study were (i) to investigate the accumulative properties of the subhorizon Ofh and (ii) to answer the question whether it can be used as a useful geoindicator of temperate soil quality. To achieve these objectives, 110 soil samples (55 from the subhorizon Ofh and 55 from the horizons A (humic) or AE (humic-eluvial)) were collected from five forest areas located in the south-central Poland (Świętokrzyskie province). All samples were analysed for Ba, Ca, Cd, Cu, Fe, Hg, K, Mn, Pb, S, Ti and Zn using atomic absorption spectrometry and X-Ray fluorescence spectroscopy. Soil organic matter (SOM), C, N, pH and EC were also measured. The soil (sub)horizons studied showed significant differences in chemistry (results are presented as mean values) – pH: Ofh/A/AE 4.7/5.4/5.4, EC (µS/cm): Ofh/A/AE 415/199/107, SOM (%): Ofh/A/AE 56.2/15.9/4.08, C (%): Ofh/A/AE 32.4/9.84/3.18, N (%): Ofh/A/AE 1.01/0.34/0.11. Our results confirmed that the subhorizon Ofh acts like a sponge with regard to Cd, Hg, Zn and S. Concentrations of these elements were two to four times higher than in the lower A and AE horizons: Cd (mg/kg): Ofh/A/AE 1.38/0.839/0.255, Hg (mg/kg): Ofh/A/AE 0.203/0.187/0.055, Zn (mg/kg): Ofh/A/AE 146/90.0/43.3, and S (mg/kg): Ofh/A/AE 2077/956/534. Such a relationship was not observed for Pb, which predominated in the humic A horizon (Ofh/A/AE 60.7/112/41.4 mg/kg). These results are a step towards a better understanding of the accumulative properties of the subhorizon Ofh.
This study was supported by the Jan Kochanowski University in Kielce, Poland (a research grant SUPD.RN .24.026).

Keywords: subhorizon Ofh, geoindicator, trace and major elements, soil quality

How to cite
Sołtys A., Dołęgowska S., 2024. Soil subhorizon Ofh (organic fermentative-humic) as a ‘natural sponge’ of selected trace elements. 1st International Conference of Soil and Agriculture: Towards Soil Sustainability. https://doi.org/10.24326/ICSA1.1.07