Fakultät Agrarwissenschaften

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Die Fakultät entwickelt in Lehre und Forschung nachhaltige Produktionstechniken der Agrar- und Ernährungswirtschaft. Sie erarbeitet Beiträge für den ländlichen Raum und zum Verbraucher-, Tier- und Umweltschutz.

Homepage: https://agrar.uni-hohenheim.de/

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3D-surface MALDI mass spectrometry imaging for visualising plant defensive cardiac glycosides in Asclepias curassavica
(2021) Dreisbach, Domenic; Petschenka, Georg; Spengler, Bernhard; Bhandari, Dhaka R.
Mass spectrometry–based imaging (MSI) has emerged as a promising method for spatial metabolomics in plant science. Several ionisation techniques have shown great potential for the spatially resolved analysis of metabolites in plant tissue. However, limitations in technology and methodology limited the molecular information for irregular 3D surfaces with resolutions on the micrometre scale. Here, we used atmospheric-pressure 3D-surface matrix-assisted laser desorption/ionisation mass spectrometry imaging (3D-surface MALDI MSI) to investigate plant chemical defence at the topographic molecular level for the model system Asclepias curassavica. Upon mechanical damage (simulating herbivore attacks) of native A. curassavica leaves, the surface of the leaves varies up to 700 μm, and cardiac glycosides (cardenolides) and other defence metabolites were exclusively detected in damaged leaf tissue but not in different regions of the same leaf. Our results indicated an increased latex flow rate towards the point of damage leading to an accumulation of defence substances in the affected area. While the concentration of cardiac glycosides showed no differences between 10 and 300 min after wounding, cardiac glycosides decreased after 24 h. The employed autofocusing AP-SMALDI MSI system provides a significant technological advancement for the visualisation of individual molecule species on irregular 3D surfaces such as native plant leaves. Our study demonstrates the enormous potential of this method in the field of plant science including primary metabolism and molecular mechanisms of plant responses to abiotic and biotic stress and symbiotic relationships.
A low-tech approach to mobilize nutrients from organic residues to produce bioponic stock solutions
(2024) Heintze, Sebastian; Beckett, Marc; Kriem, Lukas Simon; Germer, Jörn; Asch, Folkard; Liu, Guodong
Organic residues, as a nutrient source suitable of producing solutions for hydroponic crop production, have the potential to reduce the dependence on mineral fertilizers. Especially in remote and resource-constrained regions, organic residues might be the only option to produce hydroponic nutrient solutions. However, nutrient solutions made from organic residues, called bioponic solutions, are usually unbalanced in their nutrient composition, which leads to deficiencies and poor plant growth. This study aimed to experimentally develop a low-tech approach to produce bioponic stock solutions rich in NO3−, P, and K, to create a balanced bioponic solution. The mixed bioponic solution contained 58 mg L−1 NH4+-N, 43 mg L−1 NO3−-N, 50 mg L−1 PO43−-P, and 246 mg L−1 K+. This approach resulted in satisfactory levels of P, K and micronutrients. The solution was tested pure and spiked with Ca(NO3)2 on lettuce in comparison with a mineral Hoagland nutrient solution. Neither the bioponic nor the spiked bioponic solution achieved comparable lettuce yields to the Hoagland solution. The poor growth of the plants in the bioponic solution was attributed to an unfavorable NH4+:NO3− ratio, high microorganism load, and elevated pH levels. However, the approach of preparing bioponic stock solutions could be promising for future research into the production of balanced bioponic nutrient solutions from organic residues.
Abundance and symbiotic efficiency of indigenous rhizobia nodulating faba bean and common bean in southern Ethiopia
(2025) Geremu, Tadele; Abera, Girma; Lemma, Bekele; Rasche, Frank
The symbiotic association between legumes and indigenous rhizobia is crucial for enhancing legume productivity. However, inconsistent results and suboptimal performance of rhizobia inoculation in promoting legume production have been observed. In this regard, we assessed the abundance and symbiotic efficiency of indigenous rhizobia nodulating faba bean and common bean, as well as the soil factors affecting rhizobia abundance in southern Ethiopia. The study also compared the performance of indigenous rhizobia with commercial strains and mineral nitrogen treatment plants. A total of 132 soil samples were collected from barley, wheat, maize, potato, common bean, faba bean, intercropped common bean and maize, enset, and grazing land. Indigenous rhizobia were isolated and enumerated from these samples. Faba bean (FB) and common bean (CB) rhizobia population ranged from 0.0 to 1.7 x 10 4 and 1.7 x 10 1 to 1.7 x 10 7 cells g -1 soil, respectively. Rhizobia populations were significantly influenced by soil pH, EC, OC, TN, CEC, exchangeable acidity, aluminium, and the host crop occurrence. The isolated indigenous rhizobia demonstrated significant potential in enhancing nodulation, shoot dry weight, and TN accumulation in plants. Symbiotic efficiency indices revealed that over 95% of the indigenous rhizobia were effective in nodulation and shoot dry matter accumulation, indicating that naturally occurring rhizobia are efficient and may reduce the need for commercial inoculants in areas with abundant indigenous populations. However, in areas where rhizobia populations are low, strains isolated from faba bean (33FB, 84FB) and common bean (44CB, 102CB), which outperformed commercial strains should be further evaluated. The results suggest that soil rhizobia population levels should be assessed prior to inoculation to optimize nodulation and crop performance. To this end, it is emphasized to evaluate soil rhizobia strains to assess their stability and competitiveness relative to commercial inoculants across different agroecological conditions.
The active core microbiota of two high-yielding laying hen breeds fed with different levels of calcium and phosphorus
(2022) Roth, Christoph; Sims, Tanja; Rodehutscord, Markus; Seifert, Jana; Camarinha-Silva, Amélia
The nutrient availability and supplementation of dietary phosphorus (P) and calcium (Ca) in avian feed, especially in laying hens, plays a vital role in phytase degradation and mineral utilization during the laying phase. The required concentration of P and Ca peaks during the laying phase, and the direct interaction between Ca and P concentration shrinks the availability of both supplements in the feed. Our goal was to characterize the active microbiota of the entire gastrointestinal tract (GIT) (crop, gizzard, duodenum, ileum, caeca), including digesta- and mucosa-associated communities of two contrasting high-yielding breeds of laying hens (Lohmann Brown Classic, LB; Lohmann LSL-Classic, LSL) under different P and Ca supplementation levels. Statistical significances were observed for breed, GIT section, Ca, and the interaction of GIT section x breed, P x Ca, Ca x breed and P x Ca x breed (p < 0.05). A core microbiota of five species was detected in more than 97% of all samples. They were represented by an uncl. Lactobacillus (average relative abundance (av. abu.) 12.1%), Lactobacillus helveticus (av. abu. 10.8%), Megamonas funiformis (av. abu. 6.8%), Ligilactobacillus salivarius (av. abu. 4.5%), and an uncl. Fusicatenibacter (av. abu. 1.1%). Our findings indicated that Ca and P supplementation levels 20% below the recommendation have a minor effect on the microbiota compared to the strong impact of the bird’s genetic background. Moreover, a core active microbiota across the GIT of two high-yielding laying hen breeds was revealed for the first time.
An evaluation of the lineage of Brucella isolates in turkey by a whole-genome single-nucleotide polymorphism analysis
(2024) Akar, Kadir; Holzer, Katharina; Hoelzle, Ludwig E.; Yıldız Öz, Gülseren; Abdelmegid, Shaimaa; Baklan, Emin Ayhan; Eroğlu, Buket; Atıl, Eray; Moustafa, Shawky A.; Wareth, Gamal; Elkhayat, Manar; Pedersen, Karl
Brucellosis is a disease caused by the Brucella ( B. ) species. It is a zoonotic disease that affects farm animals and causes economic losses in many countries worldwide. Brucella has the ability to persist in the environment and infect the host at low doses. Thus, it is more important to trace brucellosis outbreaks, identify their sources of infection, and interrupt their transmission. Some countries already have initial data, but most of these data are based on a Multiple-Locus Variable-Number Tandem-Repeat Analysis (MLVA), which is completely unsuitable for studying the Brucella genome. Since brucellosis is an endemic disease in Turkey, this study aimed to examine the genome of Turkish Brucella isolates collected between 2018 and 2020, except for one isolate, which was from 2012. A total of 28 strains of B. melitensis ( n = 15) and B. abortus ( n = 13) were analyzed using a core-genome single-nucleotide polymorphism (cgSNP) analysis. A potential connection between the Turkish isolates and entries from Sweden, Israel, Syria, Austria, and India for B. melitensis was detected. For B. abortus , there may be potential associations with entries from China. This explains the tight ties found between Brucella strains from neighboring countries and isolates from Turkey. Therefore, it is recommended that strict measures be taken and the possible effects of uncontrolled animal introduction are emphasized.
Analysis of the species spectrum of the Diaporthe/Phomopsis complex in European soybean seeds
(2020) Hosseini, Behnoush; El-Hasan, Abbas; Link, Tobias; Vögele, Ralf
Phytopathogenic fungal species of the Diaporthe/Phomopsis complex (DPC) are associated with three highly destructive diseases on soybean: seed decay, pod and stem blight, and stem canker. They are responsible for poor seed quality and significant yield reduction in most soybean-producing areas. Precise identification and classification of DPC species are important in understanding the epidemiology of disease and to develop effective control measures. Although cultural and morphological characteristics of DPC-associated pathogens have been described, establishing a more accurate taxonomic framework seems necessary for a revaluation of the taxonomy and phylogeny of DPC species. In this study, we focused on morphological and molecular analyses of species from DPC-damaged European soybean seeds obtained from several locations throughout Europe. Colony characteristics, conidia dimensions, existence of α- and β-conidia, and formation of perithecia were evaluated in order to assign the isolates to a species morphologically. Phylogenetic relationships were determined based on sequences from beta-tubulin (TUB), translation elongation factor 1-alpha (TEF1), and nuclear ribosomal DNA internal transcribed spacers (ITS). All isolates were tested for pathogenicity on soybean with positive results. In this study, we present updated taxonomic data by combining morphological observations and molecular tools which placed 32 Diaporthe isolates into four DPC species: D. longicolla, D. caulivora, D. eres, and D. novem, which are well-known soybean pathogens.
Assessing functional properties of diet protein hydrolysate and oil from fish waste on canine immune parameters, cardiac biomarkers, and fecal microbiota
(2024) Cabrita, Ana R. J.; Barroso, Carolina; Fontes-Sousa, Ana Patrícia; Correia, Alexandra; Teixeira, Luzia; Maia, Margarida R. G.; Vilanova, Manuel; Yergaliyev, Timur; Camarinha-Silva, Amélia; Fonseca, António J. M.
Locally produced fish hydrolysate and oil from the agrifood sector comprises a sustainable solution both to the problem of fish waste disposal and to the petfood sector with potential benefits for the animal’s health. This study evaluated the effects of the dietary replacement of mainly imported shrimp hydrolysate (5%) and salmon oil (3%; control diet) with locally produced fish hydrolysate (5%) and oil (3.2%) obtained from fish waste (experimental diet) on systemic inflammation markers, adipokines levels, cardiac function and fecal microbiota of adult dogs. Samples and measurements were taken from a feeding trial conducted according to a crossover design with two diets (control and experimental diets), six adult Beagle dogs per diet and two periods of 6 weeks each. The experimental diet, with higher docosahexaenoic (DHA) and eicosapentaenoic (EPA) acids contents, decreased plasmatic triglycerides and the activity of angiotensin converting enzyme, also tending to decrease total cholesterol. No effects of diet were observed on serum levels of the pro-inflammatory cytokines interleukin (IL)-1β, IL-8, and IL-12/IL-23 p40, and of the serum levels of the anti-inflammatory adipokine adiponectin. Blood pressure, heart rate and echocardiographic measurements were similar between diets with the only exception of left atrial to aorta diameter ratio that was higher in dogs fed the experimental diet, but without clinical relevance. Diet did not significantly affect fecal immunoglobulin A concentration. Regarding fecal microbiome, Megasphaera was the most abundant genus, followed by Bifidobacterium , Fusobacterium , and Prevotella , being the relative abundances of Fusobacterium and Ileibacterium genera positively affected by the experimental diet. Overall, results from the performed short term trial suggest that shrimp hydrolysate and salmon oil can be replaced by protein hydrolysate and oil from fish by-products without affecting systemic inflammatory markers, cardiac structure and function, but potentially benefiting bacterial genera associated with healthy microbiome. Considering the high DHA and EPA contents and the antioxidant properties of fish oil and hydrolysate, it would be worthwhile in the future to assess their long-term effects on inflammatory markers and their role in spontaneous canine cardiac diseases and to perform metabolomic and metagenomics analysis to elucidate the relevance of microbiota changes in the gut.
Assessing impacts of crop area expansion and crop-livestock integration on ecosystem functions in African savannas using the coupled LUCIA and LIVSIM models
(2025) Gutai, Benjamin; Marohn, Carsten; Bateki, Christian Adjogo; Asch, Folkard
Large-scale land use change (LUC) of African Guinea savannas to crop fields is expected to cause negative impacts on ecosystem functions (ESF) and long term land productivity. The complex interactions of key processes in savannas evoked by LUC calls for a process-based modelling approach. We employed the dynamically coupled Land Use Change Impact Assessment (LUCIA) model and the Livestock Simulator (LIVSIM) which represent LUC impacts on soil processes, landscape-scale matter fluxes, seasonal grass and crop growth, and livestock nutrition, production and reproduction, depending on seasonal feed availability and quality on accessible pastures. For a rangeland in Borana, Ethiopia, two different LUC scenarios were evaluated in comparison to the baseline of traditional pasture-based land use. In the intensive LUC scenario 52% of grassland was converted into unfertilized maize fields, inaccessible for livestock. The integrated LUC scenario of the same grassland conversion rate allowed feeding maize straw and provided high-quality feed reserves from seasonally managed pastures. LUC in the intensive LUC scenario led to declining yields in the second year after conversion. Feed production on the remaining rangeland patches was insufficient for livestock nutrition, causing drops of herd body weight and herd size particularly in drought years. Resilience of herd performance to LUC was enhanced in the integrated LUC scenario when feeding maize straw and high-quality feed reserves. In both LUC scenarios, topsoil organic carbon storage decreased after ploughing shrub grassland for cultivation, and so did soil water storage capacity due to soil pore destruction. Soil erosion of less than one cm after 10 years occurred under cultivation. The simulation results indicated that the well validated model framework could predict impacts of LUC and simple crop-livestock integration on savanna ESFs, grass growth dynamics and livestock production during seasonal and inter-annual rainfall variation. This study lays the foundation for further land use scenario simulations to improve the understanding of benefits and risks caused by savanna grassland conversion.
Assessing the between-country genetic correlation in maize yield using German and Polish official variety trials
(2022) Malik, Waqas Ahmed; Buntaran, Harimurti; Przystalski, Marcin; Lenartowicz, Tomasz; Piepho, Hans-Peter
Official variety testing is performed in many countries by statutory agencies in order to identify the best candidates and make decisions on the addition to the national list. Neighbouring countries can have similarities in agroecological conditions, so it is worthwhile to consider a joint analysis of data from national list trials to assess the similarity in performance of those varieties tested in both countries. Here, maize yield data from official German and Poland variety trials for cultivation and use (VCU) were analysed for the period from 1987 to 2017. Several statistical models that incorporate environmental covariates were fitted. The best fitting model was used to compute estimates of genotype main effects for each country. It is demonstrated that a model with random genotype-by-country effects can be used to borrow strength across countries. The genetic correlation between cultivars from the two countries equalled 0.89. The analysis based on agroecological zones showed high correlation between zones in the two countries. The results also showed that 22 agroecological zones in Germany can be merged into five zones, whereas the six zones in Poland had very high correlation and can be considered as a single zone for maize. The 43 common varieties which were tested in both countries performed equally in both countries. The mean performances of these common varieties in both countries were highly correlated.
Assessing the capability of YOLO- and transformer-based object detectors for real-time weed detection
(2025) Allmendinger, Alicia; Saltık, Ahmet Oğuz; Peteinatos, Gerassimos G.; Stein, Anthony; Gerhards, Roland
Assessing the capability of YOLO- and transformer-based object detectors for real-time weed detection
(2025) Allmendinger, Alicia; Saltık, Ahmet Oğuz; Peteinatos, Gerassimos G.; Stein, Anthony; Gerhards, Roland
Spot spraying represents an efficient and sustainable method for reducing herbicide use in agriculture. Reliable differentiation between crops and weeds, including species-level classification, is essential for real-time application. This study compares state-of-the-art object detection models-YOLOv8, YOLOv9, YOLOv10, and RT-DETR-using 5611 images from 16 plant species. Two datasets were created, dataset 1 with training all 16 species individually and dataset 2 with grouping weeds into monocotyledonous weeds, dicotyledonous weeds, and three chosen crops. Results indicate that all models perform similarly, but YOLOv9s and YOLOv9e, exhibit strong recall (66.58 % and 72.36 %) and mAP50 (73.52 % and 79.86 %), and mAP50-95 (43.82 % and 47.00 %) in dataset 2. RT-DETR-l, excels in precision reaching 82.44 % (dataset 1) and 81.46 % (dataset 2) making it ideal for minimizing false positives. In dataset 2, YOLOv9c attains a precision of 84.76% for dicots and 78.22% recall for Zea mays L.. Inference times highlight smaller YOLO models (YOLOv8n, YOLOv9t, and YOLOv10n) as the fastest, reaching 7.64 ms (dataset 1) on an NVIDIA GeForce RTX 4090 GPU, with CPU inference times increasing significantly. These findings emphasize the trade-off between model size, accuracy, and hardware suitability for real-time agricultural applications.
Assessing the combination efficiency of some unconventional feed resources with concentrates and Chloris gayana grass in mitigating ruminal methane production in vitro
(2024) Melesse, Aberra; Steingass, Herbert; Holstein, Julia; Titze, Natascha; Rodehutscord, Markus
In a preliminary in vitro study, leaves of Acacia nilotica, Prosopis juliflora, Cajanus cajan, Leucaena leucocephala and seed kernel of Mangifera indica were identified as potential candidates in mitigating ruminal methane (CH4) production. The objective of the current study was to investigate the combination efficiency of these unconventional feeds with concentrate mix (CM) or Chloris gayana grass in CH4 reduction. Two feed combinations in different proportions were incubated in vitro with buffered rumen fluid at Hohenheim Gas test. In combination 1, C. gayana and CM were included as basal substrates, while in combination 2, A. nilotica, P. juliflora, C. cajan, L. leucocephala or M. indica seed kernel were included as CH4 reducing supplements at different proportions. The CH4 reducing potentials of feed combinations were presented as the ratio of CH4 to net gas production and expressed as percentage (pCH4). The pCH4 for CM and C. gayana was 16.7% and 16.9%, respectively, while it ranged from 3.18% in A. nilotica to 13.1% in C. cajan. The pCH4 was reduced (p < 0.05) from 14.6% to 9.39% when A. nilotica was combined with CM. In combination of L. leucocephala or C. cajan with CM, the pCH4 (p < 0.05) was reduced from 16.5% and 16.6% with the lowest proportion to 15.1% and 15.2% with the highest inclusion rate respectively. The combination of C. gayana with L. leucocephala or C. cajan reduced (p < 0.05) the pCH4 from 16.3% and 16.4% to 15.1% and 14.9% respectively. The pCH4 was reduced (p < 0.05) from 13.4% to 7.60% when A. nilotica was combined with C. gayana. Estimated digestible organic matter (dOM) and metabolizable energy (ME) increased (p < 0.05) with increasing proportions of M. indica seed kernel with CM or C. gayana. In conclusion, the combination of the basal substrates with unconventional supplements resulted in CH4 reduction without affecting the dOM and ME at lower inclusion rates. Animal‐based experiments await to validate in vitro findings.
Assessment of different methods to determine NH₃ emissions from small field plots after fertilization
(2025) Götze, Hannah; Brokötter, Julian; Frößl, Jonas; Kelsch, Alexander; Kukowski, Sina; Pacholski, Andreas Siegfried; Anderson, William A.
Ammonia (NH₃) emissions affect the environment, climate and human health and originate mainly from agricultural sources like synthetic nitrogen fertilizers. Accurate and replicable measurements of NH₃ emissions are crucial for research, inventories and evaluation of mitigation measures. There exist specific application limitations of NH₃ emission measurement techniques and a high variability in method performance between studies, in particular from small plots. Therefore, the aim of this study was the assessment of measurement methods for ammonia emissions from replicated small plots. Methods were evaluated in 18 trials on six sites in Germany (2021–2022). Urea was applied to winter wheat as an emission source. Two small-plot methods were employed: inverse dispersion modelling (IDM) with atmospheric concentrations obtained from Alpha samplers and the dynamic chamber Dräger tube method (DTM). Cumulative NH₃ losses assessed by each method were compared to the results of the integrated horizontal flux (IHF) method using Alpha samplers (Alpha IHF) as a micrometeorological reference method applied in parallel large-plot trials. For validation, Alpha IHF was also compared to IHF/ZINST with Leuning passive samplers. Cumulative NH₃ emissions assessed using Alpha IHF and DTM showed good agreement, with a relative root mean square error (rRMSE) of 11%. Cumulative emissions assessed by Leuning IHF/ZINST deviated from Alpha IHF, with an rRMSE of 21%. For low-wind-speed and high-temperature conditions, NH3 losses detected with Alpha IDM had to be corrected to give acceptable agreement (rRMSE 20%, MBE +2 kg N ha−1). The study shows that quantification of NH₃ emissions from small plots is feasible. Since DTM is constrained to specific conditions, we recommend Alpha IDM, but the approach needs further development.
Back to the roots: understanding banana below‐ground interactions is crucial for effective management of Fusarium wilt
(2022) Were, Evans; Viljoen, Altus; Rasche, Frank
Global banana production is affected by Fusarium wilt, a devastating disease caused by the soilborne root‐infecting fungus, Fusarium oxysporum f. sp. cubense (Foc). Fusarium wilt is notoriously difficult to manage because infection arises through complex below‐ground interactions between Foc, the plant, and the soil microbiome in the root–soil interface, defined as the rhizosphere. Interactions in the rhizosphere play a pivotal role in processes associated with pathogen development and plant health. Modulation of these processes through manipulation and management of the banana rhizosphere provides an auspicious prospect for management of Fusarium wilt. Yet, a fundamental understanding of interactions in the banana rhizosphere is still lacking. The objective of this review is to discuss the state‐of‐the‐art of the relatively scant data available on banana below‐ground interactions in relation to Fusarium wilt and, as a result, to highlight key research gaps. Specifically, we seek to understand (a) the biology of Foc and its interaction with banana; (b) the ecology of Foc, including the role of root‐exuded metabolites in rhizosphere interactions; and (c) soil management practices and how they modulate Fusarium wilt. A better understanding of molecular and ecological factors influencing banana below‐ground interactions has implications for the development of targeted interventions in the management of Fusarium wilt through manipulation of the banana rhizosphere.
The baobab (Adansonia digitata L.) in Southern Kenya–a study on status, distribution, use and importance in Taita–Taveta County
(2020) Fischer, Sahrah; Jäckering, Lisa; Kehlenbeck, Katja
Baobab (Adansonia digitata L.) is a multipurpose, drought resistant, wild fruit tree, endemic to arid and semi-arid lands of Sub-Saharan Africa. Baobab populations have been showing a lack of regeneration, and therefore causes concern for the species survival. This study investigated the state, distribution and use of baobabs in an under-researched population in Kenya, to identify the potential for further use and development of baobab resources. A baobab population was chosen in Taita–Taveta County, covering a sample area of 2015 km2. A systematic stratified transect survey was done to map baobab distribution using 49 transects (0.5 × 3 km each). The diameter at breast height and other indicators were measured on all baobabs in the transects to assess population status and health. A household survey (n = 46) and focus group discussions (n = 12) were done following the transect survey to gain an idea on the uses and distribution of baobab. In total, 432 baobab trees were measured and recorded in the research area of 2015 km2. The baobabs grew in two clusters (i.e., areas with a baobab density of ≥0.08 baobabs/ha). Both clusters showed rejuvenating populations. The main factors identified by the respondents, positively and negatively influencing baobab distribution were environmental factors, wildlife, human impact and commercial value. The study area shows a great potential for baobab to become an important part of the diet, due to its current use as an emergency food during food scarce times, and the relatively healthy and stable rejuvenating populations.
Bayesian inference of root architectural model parameters from synthetic field data
(2021) Morandage, Shehan; Laloy, Eric; Schnepf, Andrea; Vereecken, Harry; Vanderborght, Jan
Background and aims: Characterizing root system architectures of field-grown crops is challenging as root systems are hidden in the soil. We investigate the possibility of estimating root architecture model parameters from soil core data in a Bayesian framework. Methods: In a synthetic experiment, we simulated wheat root systems in a virtual field plot with the stochastic CRootBox model. We virtually sampled soil cores from this plot to create synthetic measurement data. We used the Markov chain Monte Carlo (MCMC) DREAM(ZS) sampler to estimate the most sensitive root system architecture parameters. To deal with the CRootBox model stochasticity and limited computational resources, we essentially added a stochastic component to the likelihood function, thereby turning the MCMC sampling into a form of approximate Bayesian computation (ABC). Results: A few zero-order root parameters: maximum length, elongation rate, insertion angles, and numbers of zero-order roots, with narrow posterior distributions centered around true parameter values were identifiable from soil core data. Yet other zero-order and higher-order root parameters were not identifiable showing a sizeable posterior uncertainty. Conclusions: Bayesian inference of root architecture parameters from root density profiles is an effective method to extract information about sensitive parameters hidden in these profiles. Equally important, this method also identifies which information about root architecture is lost when root architecture is aggregated in root density profiles.
Bayesian‐optimized experimental designs for estimating the economic optimum nitrogen rate: a model‐averaging approach
(2025) Matavel, Custódio Efraim; Meyer‐Aurich, Andreas; Piepho, Hans‐Peter
Field experiments play a crucial role in optimizing nutrient application strategies and determining the economic optimum nitrogen rate (EONR), aiding stakeholders in agricultural decision‐making. These experiments tailor agricultural input management to maximize efficiency and sustainability, ultimately improving farm economics. However, the optimal setup of field experiments remains an ongoing debate, particularly regarding economic considerations such as the selection of treatment levels (design points), their spatial arrangement, and the number of replications required for statistical validity and cost‐effectiveness. This study optimizes field experiments for estimating the EONR using a model‐averaging approach within a Bayesian framework. We employed Bayesian inference and the No‐U‐turn sampler to integrate model averaging across multiple yield response models, improving robustness in EONR estimation. Stochastic optimization, specifically simultaneous perturbation stochastic approximation, was used to optimize experimental designs, and their performance was evaluated through Monte Carlo simulations. Our results show that optimized experimental designs significantly improve the precision of EONR estimates. Designs incorporating higher number of nitrogen levels provided the best trade‐off between accuracy and efficiency, minimizing bias and mean squared error. Even with a fixed total number of plots (120), increasing the number of design points resulted in lower variance, demonstrating the efficiency of well‐structured experimental designs. This research lays the groundwork for future developments in experimental methodologies with wide‐ranging implications for agricultural economics and policymaking, ultimately supporting better‐informed decision‐making. Future work should integrate environmental constraints and account for real‐world variability in treatment replication to further refine experimental optimization strategies.
Beitragspotential silvoarabler Agroforstsysteme in Baden-Württemberg zur kosteneffizienten Erreichung der EU-Klimaneutralität
(2026) Geier, Cecilia Roxanne; Bahrs, Enno
Kohlenstoffdioxid (CO2) stellt eines der bedeutendsten anthropogenen Treibhausgase (THG) und damit einen wesentlichen Treiber der Erderwärmung dar. Zur Minderung daraus resul-tierender, schwerwiegender Folgen für das menschliche Wohlergehen ist u.a. die Reduktion der CO2-Konzentration aus der Atmosphäre unerlässlich. Dafür sieht die Europäische Union (EU) vor, bis 2050 Klimaneutralität zu erreichen, indem auch die Fähigkeit zur Kohlen-stoffentnahme natürlicher Senken des LULUCF-Sektors (Land Use, Land Use Change and Fo-restry) ausgebaut wird. Begleitend zur Verabschiedung des Europäischen Klimaschutzgeset-zes 2021 und damit Rechtsverbindlichkeit der Erreichung dieser Klimaneutralität wurden di-verse Ansätze initiiert, die dies in kosteneffizienter Weise u.a. durch die Implementierung sogenannter C-Sequestrierungsmaßnahmen ermöglichen sollen. Vorliegende Arbeit be-schäftigt sich daher mit der Evaluierung des Beitragspotentials der ausgewählten C-Sequestrierungsmaßnahme Agroforst und dessen Einflussfaktoren zur kosteneffizienten Er-höhung der Senkenwirkung des LULUCF-Sektors zur Erreichung der Klimaneutralität in der EU. Anhand eines mehrstufigen, qualitativen und quantitativen Forschungsprozesses wird untersucht, inwiefern diese Maßnahme (1) kriterienkonform, (2) effektiv und (3) effizient ist, um durch die Generierung einer Kohlenstoffentnahme einen Beitrag zur Erhöhung der Sen-kenwirkung leisten zu können. Dabei spielt insbesondere die Untersuchung von Wechsel-wirkungen zwischen diesen drei Bewertungsindikatoren und deren Beeinflussung durch die Erfüllung ausgewählter Kriterien, standortspezifische Gegebenheiten und ökonomische Rahmenbedingungen eine Rolle. Da die Ausgestaltung der finanziellen Förderung bezüglich der Kosteneffizienz einen hohen Stellenwert einnimmt, werden diese Aspekte sowohl unter einer maßnahmenbasierten, als auch ergebnisbasierten Förderung untersucht. Ziele dieser Arbeit sind es, Erkenntnisse über das Zusammenwirken dieser Einflussfaktoren und der Bewertungsindikatoren zu gewinnen und das daraus resultierende Beitragspotenti-al zu quantifizieren, sowie dieses hinsichtlich seiner Bedeutung in der kosteneffizienten Er-höhung der Senkenwirkung des LULUCF-Sektors zu evaluieren. Diese Untersuchung erfolgt anhand einer dreiteiligen qualitativen und quantitativen Analyse. Beginnend mit der Identi-fizierung landnutzungsspezifischer Standards bzw. Kriterien wie Permanenz, Zusätzlichkeit oder die Vermeidung von Leakage-Effekten zur Untersuchung der Kriterienkonformität einer C-Sequestrierungsmaßnahme, folgt die Überprüfung, ob und wie diese durch Agroforst auch vor dem Hintergrund seiner praktischen Implementierung erfüllt werden können. Die Zu-sammenstellung der Kriterien basiert auf einer umfassenden Literaturrecherche von insge-samt vier Standards zur Zertifizierung von THGE-Kompensationsmaßnahmen und ergänzen-den Quellen. Anhand einer weiteren Literaturrecherche wird die diesbezügliche Kriterien-konformität von Agroforst untersucht. Eine anschließende Recherche identifiziert Konzepte aus 26 globalen Carbon Farming Projekten zur praktischen Umsetzung dieser Anforderungen und Sicherstellung der Kriterienkonformität. Diese werden in ihrer Eignung einer Bewertung durch eine Befragung mit zehn Teilnehmer:innen und einem Gruppeninterview mit sechs Expert:innen unterzogen. Daran schließt sich die Quantifizierung der Kohlenstoffentnahme eines kriterienkonformen Agroforstsystems zur Feststellung seiner Effektivität an, wobei ein besonderer Fokus auf die Bedeutung standortspezifischer Gegebenheiten gelegt wird. Diese wird mit der Erhebung daraus resultierender Vermeidungskosten verknüpft, um die Effizienz eines kriterienkon-formen und effektiven Agroforstsystems zu messen. Die zugrundeliegende Analyse wird mit-tels des im Rahmen dieser Arbeit entwickelten ökonomisch-ökologischen Landnutzungsmo-dells PALUDAF und einer angegliederten Lebenszyklusanalyse (LCA) in der Untersuchungsre-gion Baden-Württemberg (BW) durchgeführt. Aufgrund der unterschiedlichen Ansätze zur Ausgestaltung der finanziellen Förderung erfolgt die Untersuchung von Effektivität und Effi-zienz in zwei getrennten Durchläufen. Aspekte der maßnahmenbasierten Förderung werden am Beispiel von Flächenprämien für Kurzumtriebsplantagen im Rahmen der Öko-Regelung der Gemeinsamen Agrarpolitik (GAP) 2023 evaluiert. Eine anschließende Untersuchung der ergebnisbasierten Förderung erfolgt am Beispiel eines hypothetischen Agroforstsystems zur Wertholzproduktion und eines fiktiven CO2-Preises in Anlehnung an den Zertifizierungsrah-men von Kohlenstoffentnahmen der EU (CRCF-Verordnung). Die in Kapitel 2 durchgeführte Literaturrecherche, ergänzt um eine Befragung mit zehn Teil-nehmer:innen und einem Gruppeninterview mit sechs Expert:innen zeigt, dass Agroforst ei-ne hohe Kriterienkonformität aufweist, was eine Grundvoraussetzung für die kosteneffizien-te Erhöhung der Senkenwirkung darstellt. Dies liegt darin begründet, dass weniger kriterien-konforme Agroforstsysteme zwar kosteneffizienter erscheinen können, aber nicht zu einer reellen Erhöhung der Senkenwirkung führen, wenn durch Leakage-Effekte letztlich ein nega-tiver Klimaschutznutzen entsteht. Hierbei erreicht Agroforst mit 70 % Kriterienkonformität den höchsten Wert gegenüber drei anderen C-Sequestrierungsmaßnahmen „Etablierung vielfältiger Fruchtfolgen“, „Integration von Zwischenfrüchten“ und „Umwandlung von Acker- und Dauergrünland“ (50-57 %). Besonders durch die Erfüllung der Zusätzlichkeit und der Generierung positiver Nebeneffekte weist Agroforst eine höhere Kriterienkonformität auf. Allerdings führen Aspekte wie die potentielle Reemission gebundenen Kohlenstoffs und die mögliche Verursachung von Leakage-Effekten zu einer Insuffizienz in der Kriterienkonformi-tät, da diese somit nicht vollständig erreicht werden kann. Auch die praktische Umsetzung dieser Kriterien im Rahmen der Implementierung dieser C-Sequestrierungsmaßnahme ist mit Schwierigkeiten verbunden, wie etwa die zuverlässige Quantifizierung der Kohlen-stoffentnahme. Auch wenn Agroforst somit eine vergleichsweise hohe Kriterienkonformität aufweist, müssen Limitationen in der Erfüllung zugrundeliegender Kriterien anerkannt wer-den, die dessen Beitragspotential begrenzen. Darüber hinaus weisen exemplarische Ergebnisse des Landnutzungsmodells PALUDAF auf ein signifikantes THGE-Minderungspotential und somit auf eine diesbezüglich gegebene Effekti-vität von Agroforst hin. Das Minderungspotential für Kurzumtriebsplantagen in BW wird in Kapitel 3 auf bis zu 336 kt CO2eq geschätzt, dasjenige von Agroforstsystemen zur Wert-holzproduktion in Kapitel 4 auf bis zu 350 kt CO2eq. Dabei bieten Letztere zusätzlich ein hö-heres Potential zur langfristigen Kohlenstoffentnahme und erhöhen damit deren Validität. Stand heute könnte die hier geschätzte THGE-Minderungsleistung derzeitige Emissionen aus der Bodennutzung (Stand 2023) in Höhe von 1,6 Mt CO2eq um bis zu 22 % senken, bzw. die THGE des Landwirtschaftssektors in BW in Höhe von 4,4 Mt CO2eq um bis zu 8 % reduzieren. Obwohl dieses Minderungspotential einen bedeutenden Stellenwert hinsichtlich des Klima-schutzes einnehmen könnte, muss eine Limitation dieses Beitrags aufgrund des insgesamt eher geringen Anteils an THGE anerkannt werden. Darüber hinaus ist die Effektivität eines daraus resultierenden Beitrags von Agroforst zur tatsächlichen Erreichung der Klimaneutrali-tät noch geringer. Ergebnisse aus Kapitel 4 zeigen, dass das reine Potential zur Kohlen-stoffentnahme, welches letztendlich zur effektiven Erhöhung der Senkenwirkung beitragen könnte, nur noch bei maximal 205 kt CO2eq liegt. Diese Beobachtung resultiert aus der Tat-sache, dass die Reduktion von THGE im Zuge des Agroforstanbaus einerseits nicht immer dem LULUCF-Sektor zugerechnet und andererseits auch nicht zum Ausgleich unvermeidba-rer THGE verwendet werden kann, was jedoch vor dem Hintergrund der zu erreichenden Klimaneutralität essentiell ist. Damit entspräche das tatsächliche Beitragspotential einem Anteil von 60 % des eigentlichen THGE-Minderungspotentials und könnte die derzeitige Senkenwirkung des LULUCF-Sektors in BW von 5,9 Mt CO2eq (Stand 2022) um maximal 3,5 % erhöhen. Diese limitierte Effektivität geht überdies mit einer hohen Variabilität in der Kosteneffizienz einher, wie aus modellbasierten Berechnungen von Vermeidungskosten in den Kapiteln 3 und 4 deutlich wird. Je nach alternativer Landnutzungsmöglichkeit und Standorteigenschaf-ten könnten durchschnittliche Vermeidungskosten für maßnahmenbasiert geförderte Kurz-umtriebsplantagen zwischen 70 und 454 € t CO2eq−1 liegen. Analysen aus einer Vorstudie (Geier et al. 2022) deuten sogar eine Schwankungsbreite zwischen 1.535 und -30 € t CO2eq−1 an und stützen damit die Aussage der Variabilität. Für eine ergebnisbasierte Förderung der Kohlenstoffentnahme durch Wertholzproduktion in Kapitel 4 können diese zwischen 44 und 244 € t CO2eq-1 schwanken. Verglichen mit anderen THGE-Minderungsmaßnahmen im LULUCF-Sektor wie Moorwiedervernässung weist Agroforst damit eine eher mittelmäßige Kosteneffizienz auf. Es zeigt sich aber auch, dass die Effizienz von standortspezifischen Ge-gebenheiten abhängig ist und Vermeidungskosten für Wertholzproduktion in einzelnen Landkreisen und unter sonst gleichen Bedingungen zwischen 75 und 102 € t CO2eq-1 variie-ren können. Dies legt nahe, dass Agroforst in einem regionalen Kontext durchaus kosteneffi-zient sein könnte, aber diese Kosteneffizienz sehr stark an regionsspezifische Gegebenhei-ten gebunden ist, was deren Übertragbarkeit auf einen überregionalen Kontext limitiert. Im weiteren Verlauf dieser Arbeit wird dieses grundsätzliche Beitragspotential weiter evalu-iert und kritisch reflektiert. Hierbei bildet die Interaktion zwischen Bewertungsindikatoren und Einflussfaktoren wie der Erfüllung von Kriterien, standortspezifischer Gegebenheiten und ökonomischer Rahmenbedingungen einen zentralen Aspekt der Analyse. Ergebnisse zeigen hierbei eine komplexe Interaktion zwischen Bewertungsindikatoren und Einflussfak-toren, was die Erzielung eines Beitrags zur kosteneffizienten Erhöhung der Senkenwirkung erschwert. Eine teilweise diametrale Korrelation zwischen den Indikatoren bedingt, dass de-ren Optimierung zumindest z. T. mit einem Trade-off verbunden ist. Dennoch ist zumindest eine moderate Förderung von Agroforst empfehlenswert, da dieser neben der alleinigen Kohlenstoffentnahme als Beitrag zur Klimawandelminderung auch durch weitere positive Nebeneffekte in der Klimawandelanpassung relevant sein könnte, sowie generell dem Er-halt der Senkenwirkung dienen kann und sich als gegenüber anderen Maßnahmen zur Er-höhung der Senkenwirkung effektiver erweist. In diesem Zusammenhang sollte eine EU-weite, angepasste Förderung etabliert werden, um räumliche Disparitäten vor dem Hinter-grund der regionalen Effizienzunterschiede von Agroforst ausnutzen zu können: Investitio-nen in Agroforst werden dann möglicherweise vorrangig dort getätigt, wo die regionalen Gegebenheiten die höchste Effizienz versprechen. Somit könnte eine flächendeckende und gegebenenfalls differenzierte Förderung die unterschiedlichen regionalen Potenziale nut-zen, um eine effizientere Gesamtallokation der Fördermittel zu erreichen. Dies könnte etwa im Rahmen der GAP durch die Anpassung nationaler Strategiepläne und die Aufnahme der Öko-Regelung zur EU-weit harmonisierten Förderung von Agroforst erfolgen. Wo sich Agro-forst kosteneffizient zur Generierung einer Kohlenstoffentnahme umsetzen lässt, könnte in wenigen Fällen auch eine ergebnisbasierte Förderung gerechtfertigt sein. Dies setzt jedoch voraus, dass sowohl die Generierung der Kohlenstoffentnahme selbst als auch zugrundelie-gende, administrative Rahmenbedingungen im Zuge der ergebnisbasierten Förderung mög-lichst kosteneffizient sind. Dies ist der Fall, wenn ein Anbaustandort beispielsweise aufgrund geringer ökonomischer Vorzüglichkeit alternativer Kulturen niedrige Opportunitätskosten bei Erzielung vergleichsweise hoher C-Bindungsleistung und möglichst moderaten Leakage-Effekten aufweist, wie etwa bei extensivem Getreideanbau auf Böden mittlerer Güte. Die Etablierung einer zentralen Zertifizierungsinstanz mit standardisierten Quantifizierungs- und Verifizierungsprozessen kann die Transaktionskosten dieser Förderart minimieren. Zusammenfassend kann aus der vorliegenden Arbeit geschlossen werden, dass Agroforst un-ter den passenden Rahmenbedingungen einen signifikanten Beitrag zur kosteneffizienten Erhöhung der Senkenwirkung leisten könnte. Allerdings ist der Beitrag sowohl gering als auch räumlich variabel, was die gezielte Ausnutzung dieses Potentials erschwert. Eine finan-zielle Förderung kann hierin dienlich sein, ist aber ebenso in ihrer Lenkungswirkung be-grenzt. Es sollte daher von einer großflächigen Fokussierung auf die Kohlenstoffentnahme durch Agroforst Abstand genommen und dieser stattdessen als ganzheitliche Strategie ne-ben vielen anderen Maßnahmen zur Klimawandelanpassung und Restauration des LULUCF-Sektors erachtet werden. Diese Arbeit liefert damit wichtige Erkenntnisse für die Bedeutung von Agroforst im Rahmen einer ganzheitlichen Klimaschutzpolitik. Aufgrund der Vielfältig-keit und Aussagekraft der adressierten Aspekte sind die Ergebnisse sowohl für Politi-ker:innen, als auch Praktiker:innen und Forscher:innen im Bereich der Förderung, Umset-zung und Evaluation von Agroforstsystemen und deren Auswirkungen auf die THGE-Mitigation relevant.
Biomonitoring via DNA metabarcoding and light microscopy of bee pollen in rainforest transformation landscapes of Sumatra
(2022) Carneiro de Melo Moura, Carina; Setyaningsih, Christina A.; Li, Kevin; Merk, Miryam Sarah; Schulze, Sonja; Raffiudin, Rika; Grass, Ingo; Behling, Hermann; Tscharntke, Teja; Westphal, Catrin; Gailing, Oliver
Background: Intense conversion of tropical forests into agricultural systems contributes to habitat loss and the decline of ecosystem functions. Plant-pollinator interactions buffer the process of forest fragmentation, ensuring gene flow across isolated patches of forests by pollen transfer. In this study, we identified the composition of pollen grains stored in pot-pollen of stingless bees, Tetragonula laeviceps , via dual-locus DNA metabarcoding (ITS2 and rbcL ) and light microscopy, and compared the taxonomic coverage of pollen sampled in distinct land-use systems categorized in four levels of management intensity (forest, shrub, rubber, and oil palm) for landscape characterization. Results: Plant composition differed significantly between DNA metabarcoding and light microscopy. The overlap in the plant families identified via light microscopy and DNA metabarcoding techniques was low and ranged from 22.6 to 27.8%. Taxonomic assignments showed a dominance of pollen from bee-pollinated plants, including oil-bearing crops such as the introduced species Elaeis guineensis (Arecaceae) as one of the predominant taxa in the pollen samples across all four land-use types. Native plant families Moraceae, Euphorbiaceae, and Cannabaceae appeared in high proportion in the analyzed pollen material. One-way ANOVA (p > 0.05), PERMANOVA (R² values range from 0.14003 to 0.17684, for all tests p-value > 0.5), and NMDS (stress values ranging from 0.1515 to 0.1859) indicated a lack of differentiation between the species composition and diversity of pollen type in the four distinct land-use types, supporting the influx of pollen from adjacent areas. Conclusions: Stingless bees collected pollen from a variety of agricultural crops, weeds, and wild plants. Plant composition detected at the family level from the pollen samples likely reflects the plant composition at the landscape level rather than the plot level. In our study, the plant diversity in pollen from colonies installed in land-use systems with distinct levels of forest transformation was highly homogeneous, reflecting a large influx of pollen transported by stingless bees through distinct land-use types. Dual-locus approach applied in metabarcoding studies and visual pollen identification showed great differences in the detection of the plant community, therefore a combination of both methods is recommended for performing biodiversity assessments via pollen identification.
Bird species richness and diversity responses to land use change in the Lake Victoria Basin, Kenya
(2024) Mugatha, Simon M.; Ogutu, Joseph O.; Piepho, Hans-Peter; Maitima, Joseph M.
The increasing demand for cultivated lands driven by human population growth, escalating consumption and activities, combined with the vast area of uncultivated land, highlight the pressing need to better understand the biodiversity conservation implications of land use change in Sub-Saharan Africa. Land use change alters natural wildlife habitats with fundamental consequences for biodiversity. Consequently, species richness and diversity typically decline as land use changes from natural to disturbed. We assess how richness and diversity of avian species, grouped into feeding guilds, responded to land use changes, primarily expansion of settlements and cultivation at three sites in the Lake Victoria Basin in western Kenya, following tsetse control interventions. Each site consisted of a matched pair of spatially adjacent natural/semi-natural and settled/cultivated landscapes. Significant changes occurred in bird species richness and diversity in the disturbed relative to the natural landscape. Disturbed areas had fewer guilds and all guilds in disturbed areas also occurred in natural areas. Guilds had significantly more species in natural than in disturbed areas. The insectivore/granivore and insectivore/wax feeder guilds occurred only in natural areas. Whilst species diversity was far lower, a few species of estrildid finches were more common in the disturbed landscapes and were often observed on the scrubby edges of modified habitats. In contrast, the natural and less disturbed wooded areas had relatively fewer estrildid species and were completely devoid of several other species. In aggregate, land use changes significantly reduced bird species richness and diversity on the disturbed landscapes regardless of their breeding range size or foraging style (migratory or non-migratory) and posed greater risks to non-migratory species. Accordingly, land use planning should integrate conservation principles that preserve salient habitat qualities required by different bird species, such as adequate patch size and habitat connectivity, conserve viable bird populations and restore degraded habitats to alleviate adverse impacts of land use change on avian species richness and diversity.

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