Institut für Bodenkunde und Standortslehre

Permanent URI for this collectionhttps://hohpublica.uni-hohenheim.de/handle/123456789/10

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Drought impacts on plant–soil carbon allocation - integrating future mean climatic conditions
(2025) Leyrer, Vinzent; Blum, Juliette; Marhan, Sven; Kandeler, Ellen; Zimmermann, Telse; Berauer, Bernd J.; Schweiger, Andreas H.; Canarini, Alberto; Richter, Andreas; Poll, Christian
Droughts affect soil microbial abundance and functions—key parameters of plant–soil carbon (C) allocation dynamics. However, the impact of drought may be modified by the mean climatic conditions to which the soil microbiome has previously been exposed. In a future warmer and drier world, effects of drought may therefore differ from those observed in studies that simulate drought under current climatic conditions. To investigate this, we used the field experiment ‘Hohenheim Climate Change,’ an arable field where predicted drier and warmer mean climatic conditions had been simulated for 12 years. In April 2021, we exposed this agroecosystem to 8 weeks of drought with subsequent rewetting. Before drought, at peak drought, and after rewetting, we pulse‐labelled winter wheat in situ with 13CO2 to trace recently assimilated C from plants to soil microorganisms and back to the atmosphere. Severe drought decreased soil respiration (−35%) and abundance of gram‐positive bacteria (−15%) but had no effect on gram‐negative bacteria, fungi, and total microbial biomass C. This pattern was not affected by the mean precipitation regime to which the microbes had been pre‐exposed. Reduced mean precipitation had, however, a legacy effect by decreasing the proportion of recently assimilated C allocated to the microbial biomass C pool (−50%). Apart from that, continuous soil warming was an important driver of C fluxes throughout our experiment, increasing plant biomass, root sugar concentration, labile C, and respiration. Warming also shifted microorganisms toward utilizing soil organic matter as a C source instead of recently assimilated compounds. Our study found that moderate shifts in mean precipitation patterns can impose a legacy on how plant‐derived C is allocated in the microbial biomass of a temperate agroecosystem during drought. The overarching effect of soil warming, however, suggests that how temperate agroecosystems respond to drought will mainly be affected by future temperature increases.
An overall review on influence of root architecture on soil carbon sequestration potential
(2024) Srivastava, R. K.; Yetgin, Ali; Srivastava, R. K.; Institute of Soil Science and Land Evaluation, Biogeophysics, University of Hohenheim, 70599, Stuttgart, Germany; Yetgin, Ali; Toros Agri Industry, Research and Development Center, Mersin, Turkey
Soil carbon sequestration is a vital ecosystem function that mitigates climate change by absorbing atmospheric carbon dioxide (CO2). Root characteristics such as depth, diameter, length, and branching pattern affect soil carbon dynamics through root-soil interactions and organic matter breakdown. Here we review field surveys, laboratory analysis, and mathematical modeling to understand how root structures affect soil carbon storage. Further, certain root features increase soil carbon sequestration, suggesting that selective breeding and genetic engineering of plants could maximize this ecological benefit. However, more research is needed to understand the complex interactions between roots, soil biota, and soil organic matter under changing environmental conditions. In addition, the benefit of climate change mitigation methods and soil carbon models from the inclusion of root architecture was reviewed. Studies in the realm of root-soil interactions encompass a variety of academic fields, including agronomy, ecology, soil science, and plant physiology. Insights into how roots interact with their soil environment and the effects of these interactions on plant health, agricultural productivity, and environmental sustainability have been gained through this research.
Quantification of soil microbial functional genes as potential new method in environmental risk assessment of pesticides
(2025) Stache, Fabian; Ditterich, Franziska; Hochmanová, Zuzana; Hofman, Jakub; Poll, Christian; Kandeler, Ellen
Pesticides can have adverse effects on soil microorganisms, but they are underrepresented in the currently required OECD 216 test for environmental risk assessment of plant protection products (PPP). The guideline monitors soil microbial nitrogen transformation over 28 days, potentially missing long-term effects of persistent pesticides. Additionally, nitrate alone may be not sensitive enough to detect disruptions in microbial functions. We investigated whether functional gene analysis could provide a more sensitive bioindicator of pesticide impact. To compare this method with the standard test, we conducted a microcosm experiment following the OECD 216 experimental setup. To capture long-term effects beyond the typical test period, we extended the incubation duration to 56 days. Four different concentrations of the persistent fungicide boscalid were added based on predicted environmental concentration. We also assessed microbial responses to fungicide exposure by measuring classical soil microbial parameters. According to the standard test, boscalid had no harmful long-term effects on soil microbiota. In contrast, our analysis of functional genes found an overall reduction in the acid phosphatase-encoding phoN gene abundance on Day 56, and correspondingly, in acid phosphatase activity in the highest fungicide treatment. Simultaneously, we observed a tendency towards lower fungal abundance based on measured copy numbers of an ITS region of nuclear ribosomal DNA (rDNA) and increased cumulative CO2 production. These results indicate a fungicide-related response of the microbial community and impaired microbial phosphorus cycling. Extending the experimental period to 56 days revealed long-term effects that would have otherwise been undetected under the typical 28-day test duration.
Synthesis of short-range ordered aluminosilicates at ambient conditions
(2021) Lenhardt, Katharina R.; Breitzke, Hergen; Buntkowsky, Gerd; Reimhult, Erik; Willinger, Max; Rennert, Thilo
We report here on structure-related aggregation effects of short-range ordered aluminosilicates (SROAS) that have to be considered in the development of synthesis protocols and may be relevant for the properties of SROAS in the environment. We synthesized SROAS of variable composition by neutralizing aqueous aluminium chloride with sodium orthosilicate at ambient temperature and pressure. We determined elemental composition, visualized morphology by microscopic techniques, and resolved mineral structure by solid-state 29Si and 27Al nuclear magnetic resonance and Fourier-transform infrared spectroscopy. Nitrogen sorption revealed substantial surface loss of Al-rich SROAS that resembled proto-imogolite formed in soils and sediments due to aggregation upon freezing. The effect was less pronounced in Si-rich SROAS, indicating a structure-dependent effect on spatial arrangement of mass at the submicron scale. Cryomilling efficiently fractured aggregates but did not change the magnitude of specific surface area. Since accessibility of surface functional groups is a prerequisite for sequestration of substances, elucidating physical and chemical processes of aggregation as a function of composition and crystallinity may improve our understanding of the reactivity of SROAS in the environment.
Unveiling wheat’s future amidst climate change in the Central Ethiopia Region
(2024) Senbeta, Abate Feyissa; Worku, Walelign; Gayler, Sebastian; Naimi, Babak; Kuhn, Arnd Jürgen; Fenu, Giuseppe
Quantifying how climatic change affects wheat production, and accurately predicting its potential distributions in the face of future climate, are highly important for ensuring food security in Ethiopia. This study leverages advanced machine learning algorithms including Random Forest, Maxent, Boosted Regression Tree, and Generalised Linear Model alongside an ensemble approach to accurately predict shifts in wheat habitat suitability in the Central Ethiopia Region over the upcoming decades. An extensive dataset consisting of 19 bioclimatic variables (Bio1–Bio19), elevation, solar radiation, and topographic positioning index was refined by excluding collinear predictors to increase model accuracy. The analysis revealed that the precipitation of the wettest month, minimum temperature of the coldest month, temperature seasonality, and precipitation of the coldest quarter are the most influential factors, which collectively account for a significant proportion of habitat suitability changes. The future projections revealed that up to 100% of the regions currently classified as moderately or highly suitable for wheat could become unsuitable by 2050, 2070, and 2090, illustrating a dramatic potential decline in wheat production. Generally, the future of wheat cultivation will depend heavily on developing varieties that can thrive under altered conditions; thus, immediate and informed action is needed to safeguard the food security of the region.

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