Funding Agency: DFG //  Duration: 2016 - 2023 // PI: Christoph Müller

Denitrification is the process of nitrate reduction which allows microbes to breathe under aerobic conditions, is a key process of reactive nitrogen from the soil as inert N2 returns to the atmosphere. The individual steps (NO3- -> NO2- -> NO -> N2O -> N2) are enzymatically controlled by a large number of pro- and eukaryotes. Active denitrifiers communities in soil exhibit distinct regulatory phenotypes (DRP), with characteristic control of individual reaction steps and end products. It is unclear whether DRPs are taxonomically fixed in denitrifiers and how much environmental conditions can change them. Although research on DRPs has been going on for over 100 years, denitrification rates and the emission of gaseous products still cannot be satisfactorily explained and predicted. While the influence of individual environmental conditions is already well understood, the complexity of the overall process with its complicated cellular regulation as a reaction to very variable factors in the soil matrix has not yet been clarified. Key parameters are the oxygen partial pressure in the soil, the content of organic material and its quality, the pH value and the composition of the microbial community, which in turn is determined by soil structure, soil chemistry and soil-plant interaction. In this project we aim to make quantitative predictions of denitrification rates as a function of soil microstructure, organic mass quality, DRPs and atmospheric boundary layer condition. We rely on the latest experimental and analytical methods (X-ray µCT, 15N tracing, NanoSIMS, microsensors, advanced flux detection, NMR spectroscopy, molecular methods including "next generation sequencing of functional gene transcripts") to achieve a very accurate spatial and temporal resolution of the process steps. Improved numerical methods and computer capacities will allow to integrate the results of the individual groups and to develop new denitrification models ranging from the microscale (phase 1) to the field scale (phase 2).

Funding Agency: Hessian State Agency for Nature Conservation, Environment and Geology (HLNUG) // Duration: 2017 - 2029 // PI: Prof. Christoph Müller, PhD

A strategic partnership exists between the Hessian State Agency for Nature Conservation, Environment and Geology (HLNUG) and the Justus Liebig University of Giessen, which is documented by the signing of a framework agreement. In addition, the HLNUG was an important associated partner in the LOEWE funding for the FACE2FACE project. The HLNUG significantly supports the implementation of the scientific results of the climate impact research carried out at the Environmental Monitoring and Climate Impact Research Station Linden (UKL) since 1998. A further 3-year grant is intended to continue the work that has been carried out together since 1998. In addition to the continuation of long-term observations (phenology, permanent observation plots) and experiments (Giessen FACE, Biochar), the factors increased CO2 concentrations and increased air temperature will be considered within the framework of the newly constructed Giessen T-FACE facility. The surveys include the continuation of existing data series as well as the inclusion of new integrative analyses, which above all form the basis for the application for further collaborative research projects.

Link to report on permanent observation plots

Moser G, Müller C (2017) Results of the passive biomonitoring from 1998-2014 on Hessian permanent observation plots in extensively cultivated grasslands.

Project report: https://www.hlnug.de/themen/fachzentrum-klimawandel/publikationen.html

The first work on the study "Climate Change and Plant Phenology in Hesse" was carried out within the framework of INKLIM (Integrated Climate Protection Programme Hesse 2012) in the years 2004-2009.

Since 2009, the study "Climate Change and Plant Phenology in Hesse" has been continued as part of the research activities at the Environmental Observatory and Climate Impact Research Station Linden (UKL), which is jointly run by the Institute for Plant Ecology of the JLU Giessen and the Hessian State Agency for Nature Conservation, Environment and Geology.

Funding Agency : LOEWE / Duration: 2022 - 2025 // PI: Dr. Gerald Moser

The industrialization of agriculture offers several fundamental problems. Decoupled material cycles with high nitrogen surpluses, greenhouse gas emissions, soil degradation and problems regarding animal welfare result. The "GreenDairy" project aims to optimize agricultural structures and to enable ecologically and economically sustainable farming. By the use of integrated animal-plant agricultural ecosystems gaps of decoupled material cycles are expected to be closed. Additionally, effects of different farming systems (low-input vs. high-input) are to be investigated.

The project draws on the research infrastructure of the organically managed Gladbacherhof, where a digitalized dairy farming system has been established. The digital animal recording, grazing control, feeding and milking robotics, which is enabled by this system, helps to compare low-input systems (mainly roughage) with high-input systems (high proportion of corn silage and concentrated feed). In addition, the project incorporates research in animal, plant, soil, and environmental sciences, as well as agricultural and food economics, to provide a comprehensive picture of the impacts of different systems.

The Institute of Plant Ecology participates in the project area "Environment" with the investigation of greenhouse gas emissions in arable and grassland areas. At this, the climate-relevant gases CO₂, CH₄ and N₂O are recorded using soil air probes and static chambers and are quantified subsequently. The measurements will be carried out over three years so that each crop in the project's crop rotation and the respective previous crops can be taken into account. Both cropland and grassland are analyzed, comparing high- and low-input areas. Thus, the aim is to minimize the emission of climate-relevant gases by an optimized agricultural system.

Funding Agency : DLR // Duration: 2022 - 2024 // PI: Prof. Christoph Mueller, PhD

Negative emission technologies that use biomass and biogenic CO2 (biobased NETs) play a central role in net-zero policy strategies. Embedded in agricultural and forestry supply chains, biobased NETs offer numerous options, but they also compete with biomass material and energy use and therefore face large uncertainties about the feasibility of their deployment. However, the deployment of bio-based NETs in Germany has not yet been evaluated in a coherent and integrated manner, especially from the perspective of local and regional deployment.
The aim of the BioNET (Multi-level assessment of biomass-based NETs) project is to create a comprehensive knowledge base for and assess biobased NETs in Germany by combining novel social science research with state-of-the-art biomass competition modeling and trade-off analysis to support local and national decision makers: (1) we compile transparent and accessible information and data on biobased NET concepts tailored to the information needs of different stakeholders, such as energy utilities or public authorities, (2) we develop novel participatory approaches to explore societal and institutional feasibility, (3) we elaborate and evaluate national biobased NET scenarios, including techno-economic modeling and an assessment of trade-offs with respect to the different Sustainable Development Goals.
As a result, the project identifies the window of opportunity for biobased NETs in Germany and enables decision makers from local to national level as well as researchers to include and prioritize the implementation of biobased NETs in their scenarios and strategies, using appropriate dissemination formats (open data, guidelines, policy briefs, etc.).

What are the consequences of climate change for Central European agriculture?

It is getting warmer - also in Hesse. What does climate change mean for Central European agriculture? In order to investigate the complex effects of carbon dioxide on plants, soils, microorganisms and insects, LOEWE's focus "FACE2FACE" combines two large open-air experimental facilities to form a research platform: the "Free Air Carbon Dioxide Enrichment" systems - FACE for short - at Justus Liebig University in Giessen and Geisenheim University of Applied Sciences. The FACE systems make it possible to regulate the carbon dioxide concentration on defined surfaces and thus simulate the expected state in the middle of the century. Based on their findings, the scientists hope to develop strategies for adapting to climate change and reducing its consequences. They will concentrate on the agricultural ecosystems of grassland, viticulture and vegetable growing, horticulture and fruit growing.

 

All information about Face2Face can be found here

To make Europe a climate-neutral continent by 2050 while ensuring food security, sustainable agricultural soil management practices must be introduced. Improved soil organic carbon (SOC) storage (sequestration) could reduce the increase in atmospheric CO₂ concentration. The long-term sequestration of SOC depends on many factors, especially interactions with other nutrients. The coupled Carbon-Nitrogen-Phosphorus cycles mediate soil organic matter formation and turnover. Soil phosphorus (P) is a key nutrient for plant growth. Limiting P content can reduce plant and microbial biomass in the soil and affect the sequestration of SOC. Altered soil P content affects microbial composition and activity, which are thought to control certain transformation pathways in the soil carbon and nitrogen cycles and influence the stabilization of GHG emissions, SOC, and nutrients.

The "ICONICA" project (ICONICA: Impact of long-term phosphorus additions on Carbon sequestration and Nitrogen Cycling in Agricultural soils) is using a series of long-term experiments on phosphorus fertilization in the EU and New Zealand to investigate the impact of varying soil P availability on SOC sequestration and GHG emissions, as well as on the carbon-nitrogen cycle in soils. Soil microbial processes associated with varying P availability in managed grassland and cropland systems will be quantified to identify mechanisms for SOC and nitrogen sequestration.

At the Institute of Plant Ecology, stable isotope techniques (labeling with ¹³C and ¹⁵N) are being applied in laboratory experiments to determine how long-term management of P fertilizers at different intensities controls soil C and N cycling and associated greenhouse gas emissions. The climate-relevant fluxes of the greenhouse gases N₂O and CO₂ from soils are measured. C and N dynamics will be assessed as a function of long-term P fertilization at different intensities. Results of ¹⁵N tracing will be matched with associated N₂O emissions and C transformations to determine soil C losses and potential C stabilization affected by long-term P fertilization. Data generated by ICONICA will be used to determine optimal soil P levels and corresponding fertilizer recommendations for farmers that include optimal SOC sequestration and minimization of GHG emissions while maintaining crop yields of various agricultural soils.

Designing agroecosystems that effectively minimize nitrogen (N) losses to the atmosphere and water, and thereby improve nitrogen use efficiency (NUE) for crop production, remains a pressing challenge for sustainable agriculture and environmental protection. Biological nitrification inhibition (BNI), a capacity first observed in certain tropical grasses, shows promise for reducing N losses in a sustainable manner. Research suggests that ribwort plantain (Plantago lanceolata) may also possess significant BNI potential, making it a promising candidate for minimizing N losses in temperate agroecosystems. However, while P. lanceolata has shown potential as a BNI plant, the scientific evidence for its effects remains inconsistent, highlighting gaps in our understanding of its mechanisms and the factors that influence its efficiency.

The PlantaGo project ("Biological nitrification inhibition by Plantago lanceolata to reduce nitrogen losses from agroecosystems") focuses on reducing N losses from agricultural soils using Plantago lanceolata, a plant well suited to temperate climates. The project investigates the extent to which P. lanceolata can influence soil N transformations by naturally producing nitrification inhibitors, with the aim of reducing harmful N₂O emissions and nitrate leaching losses. This basic research project aims to decipher the biochemical and microbial processes associated with BNI in P. lanceolata and to develop a mechanistic model that explains its mode of action within the soil-plant-atmosphere system. The knowledge gained is expected to guide the incorporation of P. lanceolata into crop rotations to minimize N losses while maintaining agricultural productivity. The project is executed in cooperation with the Research Institute for Organic Agriculture (FiBL), Switzerland, University of Bruxelles, Belgium and University of Liège, Belgium and is funded by the Swiss and Belgium National Science Foundations (SNSF and FNRS).

At Justus Liebig University Giessen, Institute for Plant Ecology, soil incubation studies using ¹⁵N-labeled fertilizers will be conducted. The aim of these experiments is to assess the effects of BNI-active metabolites from P. lanceolata and the plant itself on N dynamics. Using the Ntrace model, data on simultaneous gross N transformation rates in different N pools will be calculated. This approach will allow to distinguish between direct effects of BNI compounds on nitrification and indirect effects within the plant-soil system.  This will help to elucidate the mode of action of the BNI properties of P. lanceolata.

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• Chen, Z., J. Zhang, Z. Xiong, G. Pan, and C. Müller. 2016. Enhanced gross nitrogen transformation rates and nitrogen supply in paddy field under elevated atmospheric carbon dioxide and temperature. Soil Biology & Biochemistry 94:80-87.