- 1Die Universität für Bodenkultur Wien, Institut für Zoologie, Department für Integrative Biologie und Biodiversitätsforschung , Austria
- 2Die Universität für Bodenkultur Wien, Institut für Bodenforschung, Department für Wald- und Bodenwissenschaften, Austria
Soil organic carbon (SOC) is a key indicator of healthy soils. Among the sources contributing to the SOC pool, the role of microbial biomass and especially necromass is often overlooked. Microbial necromass sometimes reaches 40 times of the microbial biomass, emphasizing the role of soil microorganisms in carbon sequestration. However, overall, determining necromass in soils is not common. In this study, we aimed to examine (i) the microbial biomass and necromass in agriculturally used soils across Austria, Central Europe, and (ii) the effect of environmental factors and soil parameters on biomass-necromass contributions in arable and grassland ecosystems.
We sampled soils (soil corer with 2.5 cm diameter and 10 cm depth, 3 samples per site) from 400 sites across Austria, from 150 m a.s.l. up to 2500 m a.s.l. including croplands, grasslands, and grass strips. The cooled samples were analysed for microbial biomass using Chloroform Fumigation Extraction (CFE) and for microbial necromass using amino sugars extraction. Moreover, composite soil samples (2.5 cm diameter, 10 cm depth; 3 samples per site) were used to determine pH (CaCl2), SOC, texture, potassium, phosphorus, nitrogen, humus content. The climate data (mean annual air temperature and annual precipitation) was obtained from Geosphere Austria, the Austrian Federal Agency for Geology, Geophysics, Climatology and Meteorology, Vienna. Soil management data was obtained through questionnaires directly from the land owners or operators. Data were statistically analysed using CatBoost models.
Average microbial carbon (MC) across sites was 401 ± 256 mg g-1 and microbial nitrogen (MN) 65.0 ± 48.9 mg g-1. Both MC and MN significantly increased in the order croplands < grass strips < grasslands (HSD, p<0.001). Preliminary analyses showed specific effects of soil and environmental parameters on the proportion of microbial biomass and necromass in the soils.
Our results indicate that land use significantly impacts microbial biomass distribution, potentially affecting nutrient cycling and soil health. Understanding these dynamics could inform land management practices aimed at improving soil fertility and mitigating climate change through enhanced carbon sequestration.
How to cite: Monoshyn, D., Mittmannsgruber, M., Wiedenegger, E., Gruber, E., Murugan, R., Inselsbacher, E., and Zaller, J. G.: Microbial Biomass and Necromass in Austrian Soils, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3553, https://doi.org/10.5194/egusphere-egu25-3553, 2025.
