Institut für Tropische Agrarwissenschaften (Hans-Ruthenberg-Institut)

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Single-strain inoculation of Bacillus subtilis and Rhizobium phaseoli affects nitrogen acquisition of an improved mungbean cultivar
(2024) Pataczek, Lisa; Armas, Juan Carlos Barroso; Petsch, Theresa; Hilger, Thomas; Ahmad, Maqshoof; Schafleitner, Roland; Zahir, Zahir Ahmad; Cadisch, Georg; Pataczek, Lisa; Institute of Agricultural Sciences in the Tropics (Hans-Ruthenberg-Institute), University of Hohenheim, Garbenstr. 13, 70599, Stuttgart, Germany; Armas, Juan Carlos Barroso; Institute of Agricultural Sciences in the Tropics (Hans-Ruthenberg-Institute), University of Hohenheim, Garbenstr. 13, 70599, Stuttgart, Germany; Petsch, Theresa; Institute of Agricultural Sciences in the Tropics (Hans-Ruthenberg-Institute), University of Hohenheim, Garbenstr. 13, 70599, Stuttgart, Germany; Hilger, Thomas; Institute of Agricultural Sciences in the Tropics (Hans-Ruthenberg-Institute), University of Hohenheim, Garbenstr. 13, 70599, Stuttgart, Germany; Ahmad, Maqshoof; Department of Soil Science, The Islamia University of Bahawalpur, 63100, Bahawalpur, Pakistan; Schafleitner, Roland; Biotechnology, World Vegetable Center, Headquarters, 60 Yi-Min Liao, 74151, Shanhua, Tainan, Taiwan; Zahir, Zahir Ahmad; Institute of Soil and Environmental Sciences, University of Agriculture, Faisalabad, Pakistan; Cadisch, Georg; Institute of Agricultural Sciences in the Tropics (Hans-Ruthenberg-Institute), University of Hohenheim, Garbenstr. 13, 70599, Stuttgart, Germany
Plant growth-promoting rhizobacteria (PGPR) increase plant root growth, potentially improving soil nitrogen (N) uptake, and productivity. Legumes, for instance mungbean, could also benefit from a rise in potential infection sites for nodulation, thereby increasing rates of biological N2 fixation (BNF). Consequently, the objectives of this study were (i) to assess whether PGPR had an effect on mungbean root biomass and if that was linked to N accumulation and productivity; (ii) to identify whether multi-strain inoculation showed greater efficacy in increasing N accumulation and overall productivity than single-strain inoculation; (iii) to test whether N acquisition was based on BNF rather than on soil N uptake. Field trials were conducted in two seasons at the University of Agriculture, Faisalabad with mungbean cultivar NM11 and multi-strain inoculation consisting of Rhizobium phaseoli, Bacillus subtilis, and Pseudomonas fluorescens. The strains were tested additionally in the second season as single-strain inoculation. Multi-strain and inoculation with P. fluorescens alone had no effect on root biomass, total plant-N, BNF or soil N uptake. Inoculation with B. subtilis, however, resulted in significantly increased root dry matter (+ 211 kg ha− 1), total dry matter (+ 1.7 t ha− 1), and total plant-N (+ 36 kg ha− 1). Only inoculation with R. phaseoli enhanced BNF (+ 24%). Yield was not affected by any inoculation. The results suggested that total plant-N was based on soil N uptake rather than on BNF and demonstrated that only single strains affected total N accumulation, pointing to antagonistic mechanisms of the strains in a mixed inoculum.
Climate on the edge: impacts and adaptation in Ethiopia’s agriculture
(2025) Feleke, Hirut Getachew; Amdie, Tesfaye Abebe; Rasche, Frank; Mersha, Sintayehu Yigrem; Brandt, Christian; Feleke, Hirut Getachew; School of Agriculture, Department of Plant Sciences, Ambo University, Ambo P.O. Box 19, Ethiopia; Amdie, Tesfaye Abebe; School of Plant and Horticultural Sciences, Hawassa University, Hawassa P.O. Box 5, Ethiopia;; Rasche, Frank; International Institute of Tropical Agriculture (IITA), Nairobi P.O. Box 30772-00100, Kenya;; Mersha, Sintayehu Yigrem; School of Animal and Range Sciences, Hawassa University, Hawassa P.O. Box 5, Ethiopia;; Brandt, Christian; Institute of Farm Management, University of Hohenheim, 70599 Stuttgart, Germany;; Younos, Tamim; Lee, Juneseok; Parece, Tammy E.
Climate change poses a significant threat to Ethiopian agriculture, impacting both cereal and livestock production through rising temperatures, erratic rainfall, prolonged droughts, and increased pest and disease outbreaks. These challenges intensify food insecurity, particularly for smallholder farmers and pastoralists who rely on climate-sensitive agricultural systems. This systematic review aims to synthesize the impacts of climate change on Ethiopian agriculture, with a specific focus on cereal production and livestock feed quality, while exploring effective adaptation strategies that can support resilience in the sector. The review synthesizes 50 peer-reviewed publications (2020–2024) from the Climate Change Effects on Food Security project, which supports young African academics and Higher Education Institutions (HEIs) in addressing Sustainable Development Goals (SDGs). Using PRISMA guidelines, the review assesses climate change impacts on major cereal crops and livestock feed in Ethiopia and explores adaptation strategies. Over the past 30 years, Ethiopia has experienced rising temperatures (0.3–0.66 °C), with future projections indicating increases of 0.6–0.8 °C per decade resulting in more frequent and severe droughts, floods, and landslides. These shifts have led to declining yields of wheat, maize, and barley, shrinking arable land, and deteriorating feed quality and water availability, severely affecting livestock health and productivity. The study identifies key on-the-ground adaptation strategies, including adjusted planting dates, crop diversification, drought-tolerant varieties, soil and water conservation, agroforestry, supplemental irrigation, and integrated fertilizer use. Livestock adaptations include improved breeding practices, fodder enhancement using legumes and local browse species, and seasonal climate forecasting. These results have significant practical implications: they offer a robust evidence base for policymakers, extension agents, and development practitioners to design and implement targeted, context-specific adaptation strategies. Moreover, the findings support the integration of climate resilience into national agricultural policies and food security planning. The Climate Change Effects on Food Security project’s role in generating scientific knowledge and fostering interdisciplinary collaboration is vital for building institutional and human capacity to confront climate challenges. Ultimately, this review contributes actionable insights for promoting sustainable, climate-resilient agriculture across Ethiopia.
Genotypic responses to combined effects of VPD and salinity in hydroponically grown tomato and cucumber
(2025) Puppala, Hemanth Kumar; Germer, Jörn; Asch, Folkard; Puppala, Hemanth Kumar; Hans‐Ruthenberg‐Institute for Tropical Agricultural Sciences, Universität Hohenheim, Stuttgart, Germany; Germer, Jörn; Hans‐Ruthenberg‐Institute for Tropical Agricultural Sciences, Universität Hohenheim, Stuttgart, Germany; Asch, Folkard; Hans‐Ruthenberg‐Institute for Tropical Agricultural Sciences, Universität Hohenheim, Stuttgart, Germany
To reduce pressure on arable land and water resources, crops can be grown in controlled environments that allow one to recuperate water transpired by plants. This would reduce water demand and potentially allow the use of saline water. However, condensing atmospheric water affects the vapor pressure deficit (VPD), which will affect plant transpiration, nutrient transport, salt uptake, and ultimate growth. This study examined responses of two genotypes of tomato and cucumber during the vegetative phase to varying VPD levels (3.1 and 1.9 kPa) and NaCl concentrations (0 and 30 mM) grown in hydroponic solutions. Under higher VPD (3.1 kPa), transpiration significantly increased in both tomato and cucumber, driving higher water loss. In tomatoes, higher VPD (3.1 kPa) increased the total dry biomass of the Saluoso genotype from 4.3 to 7.1 g and of the Sweeterno genotype from 4.9 to 7.3 g. Root zone salinity diminished the differences in biomass induced by VPD, with little effect on biomass accumulation in both tomato genotypes. Root zone salinity consistently reduced dry weight in cucumber, lowering Addison's from 15.5 to 9.5 g and Proloog's from 13.5 to 10.0 g, regardless of VPD. Unlike tomato, cucumber did not respond to VPD and was more sensitive to salinity. These findings indicate that in hydroponic cultivation, particularly in protected environments, the possibility of producing clean water alongside crop production depends on species‐specific responses. In tomatoes, high VPD enhanced growth and demonstrated compatibility with the use of saline water, supporting the dual goal of productivity and water recovery. However, in cucumbers, the sensitivity to salinity and lack of response to VPD highlight the need for careful species selection and management to achieve sustainable water use and crop production.
A multifaceted analysis of Myanmar’s rice sector: gender perspectives, international competitiveness, and farmers’ emotional well-being
(2025) Chan, Nandar Aye; Zeller, Manfred
The agricultural sector is vital to Myanmar’s economic development, food security, and poverty reduction. However, recent global shifts in commodity markets, combined with local crises such as climate change, the COVID-19 pandemic, conflicts, economic instability, and rising fertilizer prices and operational costs, have significantly affected Myanmar’s agri-food sector. These challenges threaten the performance of the agricultural sector, particularly the rice sector, which is essential for many livelihoods, rural employment, and export earnings. The sector faces declining productivity, reduced incomes, rising debt burdens, and increased vulnerability, especially among smallholder farmers, including women. Therefore, the Ministry of Agriculture, Livestock, and Irrigation (MOALI) is dedicated to strengthening the rice sector through promoting inclusive gender roles, enhancing competitiveness in the domestic and international rice markets, and safeguarding the socio-economic well-being of all farmers. Addressing Myanmar’s key agricultural challenges and aligning with the objectives of MOALI, this dissertation investigates three critical areas (Chapters 2 to 4) to make a modest knowledge contribution to the sustainability and long-term development of the country’s rice sector. Despite government initiatives and extensive research on Myanmar’s rice sector, three important aspects remain underexplored: the gender gap in productivity, cost competitiveness, and the role of productivity in mediating shocks to farmers’ well-being. Specifically, this dissertation has three main objectives: 1) to estimate the magnitude of the gender gap in rice productivity and identify the factors contributing to this gap; 2) to analyze the cost competitiveness of rice production by examining production costs, cost efficiency, and the potential effect of improving cost efficiency on the country’s global competitiveness; and 3) to examine the effects of shocks on farmers’ well-being and explore how rice productivity mediates this relationship. Understanding these issues is crucial for designing policies that improve the performance of Myanmar’s rice sector and strengthen farmers’ resilience. The dissertation employs a quantitative approach, using household survey data and other secondary data sources. Particularly, data for Chapters 2 and 3 originate from the 2014 Area-Based Farm Household Survey in the Ayeyarwady Delta Region, administered by the International Rice Research Institute (IRRI) under the Metrics and Indicators for Tracking in the Global Rice Science Partnership project. Chapter 3 also incorporates nationwide phone survey datasets, including the Myanmar Household Welfare Survey (MHWS) and the Myanmar Agricultural Performance Survey (MAPS), conducted by the International Food Policy Research Institute (IFPRI) during 2021-2022. This cumulative dissertation consists of five chapters. Chapter 1 presents the introduction. Chapter 2 examines the gender gap. Chapter 3 focuses on the cost competitiveness of Myanmar’s rice sector. Then, Chapter 4 investigates the mediating role of rice productivity in the shocks-happiness relationship, and Chapter 5 concludes the dissertation and provides policy recommendations. Chapter 2 presents an analysis of the gender productivity gap in Myanmar’s rice sector. The analysis focuses on the Ayeyarwady Delta region, one of the three major agroecological zones for rice cultivation in Myanmar, using IRRI regional plot-level data. The study addresses seasonal variation and assesses jointly managed plots. The Oaxaca-Blinder mean decomposition approach is used to identify the causes of gender differences in monsoon and summer paddy productivity. The empirical findings show that women managers are 7 percent less productive than men in monsoon paddy production, with 95 percent of this gap explained by structural effects. Plots jointly managed by women and men outperform those managed by either women or men alone in summer paddy production. The results show that seasonality affects the disparity in gender productivity. Divorced women account for a large portion of the productivity differential among non-married women managers. Initiatives to eliminate the gender yield gap in Myanmar should pay attention to the unique requirements and obstacles that women encounter throughout different seasons and tailor their interventions accordingly. Chapter 3 conducts a comparative analysis of production costs among major rice-producing countries and estimates the cost efficiency of rice farming in Myanmar using a stochastic frontier cost function model. Moreover, this study examines the link between cost efficiency and domestic resource costs (DRC), a key indicator of global competitiveness in rice production. The study also considers the seasonal variations in Myanmar during both the dry and wet seasons. The findings show that Myanmar ranks as the second least expensive rice-producing country among selected Asian countries. The mean cost efficiencies are 89% and 86% for the dry and wet seasons, respectively. Both dry and wet seasons of rice production demonstrate a comparative advantage. The results also show that cost efficiency positively contributes to global competitiveness in both seasons. Focusing on education, farm size, seed procurement strategies, and training programs can increase cost efficiency, thereby further improving global competitiveness in rice production. Chapter 4 examines the effects of shocks on farmers’ happiness in Myanmar and explores the mediation role of rice productivity in this relationship. The study uses nationwide phone survey datasets from Myanmar, provided by the IFPRI, specifically focusing on the rice sector to assess productivity. The study applies the mediation analysis outlined by Acharya et al. (2016) and estimates the average controlled direct effect (ACDE) of shocks while accounting for rice productivity as a mediator. To ensure robustness, additional causal mediation analysis is employed. The results indicate that rice productivity partially mediates the shock-happiness relationship. This suggests that shocks influence happiness through additional pathways beyond productivity. Moreover, farmers’ happiness is more directly influenced by recent productivity than by past agricultural performance. However, past shocks continue to have a significant and lingering effect on their happiness. These findings highlight the need for policymakers to mitigate the impact of shocks on well-being not only by improving rice productivity but also by addressing other factors that influence farmers’ happiness. The findings of this dissertation contribute to the literature on the development of Myanmar’s rice sector. Firstly, providing the first empirical evidence of the gender gap in productivity can help inform targeted policy interventions to increase rice productivity while addressing the specific needs of men and women in rice production. Secondly, it provides scalable insights to promote the competitiveness, sustainability, and efficiency of rice production, which not only benefits Myanmar but also contributes to the broader global rice market. Finally, given the importance of understanding the relationship between shocks and well-being through rice productivity, this insight provides valuable guidance for designing interventions to strengthen productivity and improve well-being in vulnerable agrarian communities facing climate-related shocks. All these chapters contribute to the understanding of seasonality, which is vital for highlighting the importance of seasonal production dynamics in Myanmar’s rice sector. Overall, Myanmar’s rice sector can achieve greater sustainability and development by promoting gender equality, enhancing competitiveness, and supporting resilience-building measures for rice-farming communities, ultimately improving farmers’ well-being.
Development of highly digestible fish feeds from locally available resources in Iran
(2025) Salehi, Hamed; Focken, Ulfert
In 2012, global aquaculture production (excluding aquatic plants) was 63.5 million tons, increasing to 94.4 million tons by 2022—a growth of 48%. In Iran, production rose by 62% during the same period, from 296,514 to 480,624 tons. Iran is a leading producer of rainbow trout (Oncorhynchus mykiss W.), contributing 15-21% of the global supply from 2012 to 2022. However, aquafeed, which accounts for 70% of production costs and 80% of environmental effluents, has been impacted by a decline in fish meal production in 2023. This may increase costs, especially for carnivorous species like rainbow trout, necessitating alternative protein sources. Currently, canola meal, a potential plant-based protein, is not widely used in Iran due to poor utilization by fish. Furthermore, local poultry by-products are viewed as low-quality protein sources compared to those in countries like Germany, due to a lack of processing technologies, which restricts their utilization in aquafeed industry. Therefore, some of these products like blood and feather meals are realised not comparable to fish meal in feeding rainbow trout for the aquafeed industry in Iran. Nutrient eutrophication in water bodies necessitates development of environmentally friendly aquafeed out of highly-digestible feed components, as well. Therefore, this research was conducted to assess the digestibility of various feed components, including poultry by-products such as PBM, BM, FeM, PPCon and plant-based proteins like CM and SBM, in rainbow trout. The test ingredients were incorporated into a semi-purified casein-based diet at a 30:70 ratio, with TiO₂ used as a marker, and then fed to the experimental fish. Feces were collected using the settling method in 57-liter aquaria. The apparent protein digestibility coefficients for PBM, FeM, PPCon, BM, CM, and SBM were 73%–93%, 73%–96%, 100%, 87%, 94%, and 97%, respectively. The most digestible feed components in terms of CP were chosen to create five fish-meal-free diets, with increasing levels of CM ranging from 20% to 40%, to compare with a casein-based diet in terms of growth performance and apparent digestibility in juvenile rainbow trout. Subsequently, the 35% CM diet, which achieved the least cost FCR, was slightly modified and extruded to feed fattening rainbow trout in tanks. This diet was then compared to a pelleted caseinbased diet to assess growth performance and nutrient effluents in tanks and simultaneously, the assessment of CP, CL,OMdigestibility as well as the availability of P in juvenile rainbow trout in aquaria set-up using the settling method. This extruded grow-out feed, which included 35% CM and approximately 32% highly digestible poultry by-products, proved to be comparable to the highly digestible semi-purified casein-based diet in terms of supporting growth performance and body criteria in rainbow trout. The utilization of macronutrients like CL, CP, and OM in this extruded feed was remarkably similar to that of the control feed (p>0.05). However, the P load from this practical diet was higher in the water compared to the control feed (p<0.05). This issue could potentially be addressed by lowering the phosphorus concentration in the feed for fish of that size and considering the phosphorus availability of each component used in the diet. This investigation showed that when terrestrial protein sources are properly combined to provide all essential nutrients to the fish, feeds without FM can not only promote high growth performance but also enable efficient nutrient utilization in rainbow trout. Lastly, properly processed poultry by-products can serve as valuable protein sources for the growing aquafeed industry in developing countries like Iran.
Towards transdisciplinary identification of suitable woody perennials for resilient agro-silvopastoral systems in the Sudano-Sahelian zone of West Africa
(2025) Roessler, Regina; Cicek, Harun; Cournac, Laurent; Gnissien, Moussa; Männle, Julia; Koomson, Eric; Founoune-Mboup, Hassna; Coulibaly, Kalifa; Diouf, Abdoul Aziz; Sanon, Hadja Oumou; Cadisch, Georg; Graefe, Sophie; Roessler, Regina; Animal Husbandry in the Tropics and Subtropics, University of Kassel, Steinstr. 19, 37213, Witzenhausen, Germany; Cicek, Harun; Department of International Cooperation, Research Institute of Organic Agriculture, Ackerstrasse 113, 5070, Frick, Switzerland; Cournac, Laurent; Eco&Sols, CIRAD, INRAE, IRD, Institut Agro, Université de Montpellier, Montpellier, France; Gnissien, Moussa; Laboratoire d’étude Et de Recherche Sur La Fertilité Des Sols Et Les Systèmes de Production (LERF-SP), Institut du Développement Rural, Université Nazi BONI, Bobo-Dioulasso, Burkina Faso; Männle, Julia; Institute of Development Research, BOKU University, Peter-Jordan-Straße 76/I 1190, Vienna, Austria; Koomson, Eric; Institute of Agricultural Sciences in the Tropics (Hans-Ruthenberg-Institute), University of Hohenheim, Garbenstr. 13, 70593, Stuttgart, Germany; Founoune-Mboup, Hassna; Institut Sénégalais de Recherches Agricoles (ISRA), BP 15532, Fann Residence, Dakar, Senegal; Coulibaly, Kalifa; Laboratoire d’étude Et de Recherche Sur La Fertilité Des Sols Et Les Systèmes de Production (LERF-SP), Institut du Développement Rural, Université Nazi BONI, Bobo-Dioulasso, Burkina Faso; Diouf, Abdoul Aziz; Centre de Suivi Ecologique (CSE), Dakar, Senegal; Sanon, Hadja Oumou; Department of Animal Production, Institut de L’Environment Et de Recherches Agricoles (INERA), BP 8645, 1973 Boulevard Tansoba Wam-Godi, 04, Ouagadougou 04, Burkina Faso; Cadisch, Georg; Institute of Agricultural Sciences in the Tropics (Hans-Ruthenberg-Institute), University of Hohenheim, Garbenstr. 13, 70593, Stuttgart, Germany; Graefe, Sophie; International Climate Initiative (IKI), Zukunft – Umwelt – Gesellschaft (ZUG) gGmbH, Stresemannstraße 69-71, Berlin, Germany
Parkland systems in the Sudano-Sahelian zone of West Africa are commonly perceived as a resilient agroforestry practice well adapted to the semi-arid climatic conditions of the region. However, there exist several knowledge gaps regarding the interplay between the different components of this agro-silvopastoral land use system. A literature review with subsequent meta-analysis was conducted to analyze the effects of woody perennials on soil, crops and livestock, for which our study found very context-specific responses. A scoring of tree and shrub species indicated a general trend of trade-off between positive impact on crops and livestock vs. impact on soil organic carbon content. The study further confirmed that Faidherbia albida (Del.) Chev. is one of the most promising parkland species, but also revealed that there are no multipurpose single species that should be promoted exclusively. The focus should rather shift to species mixtures that satisfy multiple human and environmental needs. The study also pointed out that information on the nutritional properties of the majority of browse species is particularly limited. Transdisciplinary modelling is suggested as a tool to assess the complex interactions between the different components that shape this agro-silvopastoral system at different scales.
Mineral-ecological cropping systems mitigate biodiversity-productivity trade-offs of the organic vs. conventional farming dichotomy
(2024) Kasten, Marit Kinga; Witte, Felix; Sponagel, Christian; Bahrs, Enno; Köhler, Thomas; Morinière, Jérôme; Grass, Ingo; Kasten, Marit Kinga; Ecology of Tropical Agricultural Systems, University of Hohenheim, Garbenstrasse 13, Stuttgart, Germany; Witte, Felix; Department of Farm Management, University of Hohenheim, Schwerzstrasse 44, Stuttgart, Germany; Sponagel, Christian; Department of Farm Management, University of Hohenheim, Schwerzstrasse 44, Stuttgart, Germany; Bahrs, Enno; Department of Farm Management, University of Hohenheim, Schwerzstrasse 44, Stuttgart, Germany; Köhler, Thomas; Ecology of Tropical Agricultural Systems, University of Hohenheim, Garbenstrasse 13, Stuttgart, Germany; Morinière, Jérôme; AIM – Advanced Identification Methods GmbH, Niemeyerstr.1, Leipzig, Germany; Grass, Ingo; Ecology of Tropical Agricultural Systems, University of Hohenheim, Garbenstrasse 13, Stuttgart, Germany
Conventional agriculture significantly reduces biodiversity, while organic farming promotes it, but often yields half as much. Addressing this biodiversity-productivity trade-off is crucial for future agriculture. Mineral-ecological cropping systems (MECS) have been suggested as an alternative, blending organic and conventional methods by avoiding chemical-synthetic pesticides and using mineral fertilizers. In a German experiment with 168 parcels, we compared MECS, conventional, and organic systems in terms of ecological and economic performance. Arthropod diversity was measured through standardized species collections and DNA-metabarcoding. Productivity was assessed via yields and economic profits. MECS showed similar arthropod diversity to other farming systems, achieved 90% of conventional crop yields, and produced 1.8 times of the organic yield. Profits from MECS were on average 37% higher than the conventional system with a short wheat-maize-soy crop rotation. Further farm-level studies are needed, but MECS could be a reasonable alternative to both organic and conventional farming and can mitigate biodiversity-productivity trade-offs.
Enhanced crop diversity but not smaller field size benefit bats in agricultural landscapes
(2025) Hiller, Thomas; Gall, Friederike; Grass, Ingo; Hiller, Thomas; Ecology of Tropical Agricultural Systems, University of Hohenheim, Stuttgart, Germany; Gall, Friederike; Ecology of Tropical Agricultural Systems, University of Hohenheim, Stuttgart, Germany; Grass, Ingo; Ecology of Tropical Agricultural Systems, University of Hohenheim, Stuttgart, Germany
Context: Farmland biodiversity continues to decline due to the expansion and intensification of agriculture. Historically, efforts to conserve farmland biodiversity have focused on conserving habitats outside agricultural production areas. More recently, attention has turned to the conservation potential of the cropland matrix, where reducing field size and increasing crop diversity to promote crop heterogeneity can significantly benefit farmland biodiversity. Bats are one group of farmland species that have experienced dramatic declines over recent decades. Objectives: Here we investigated the effects of crop heterogeneity (crop diversity, field size) and landscape structural elements (e.g. length of linear structures, distance to forest, proportion of semi-natural habitat) on the activity of bat functional groups. Results: Increasing crop diversity led to greater bat activity, especially for open space foraging bats. However, contrary expectations, bat activity was not affected by heterogeneity in crop configuration, i.e. field edge density. Furthermore, structural landscape elements, including hedgerows and distance to forest, were important predictors of bat activity, especially for species that hunt in highly cluttered spaces. While crop diversity clearly benefited bat activity, the lack of effect of crop configurational heterogeneity on bat foraging activity may suggest heterogeneityarea trade-offs and intensive pesticide use in small-scale vegetable production. Conclusions: Therefore, in addition to maintaining high levels of crop diversity, promoting hedgerows and tree lines between farmland and woodland may facilitate bat activity across the agricultural landscape matrix. The combination of high crop heterogeneity and structural elements provides favorable hunting grounds for bats and may promote their conservation in agricultural landscapes.
Governance of land rehabilitation and remediation: case studies of Ghana’s small-scale mining sector
(2024) Adu-Baffour, Ferdinand Ababio; Birner, Regina
The artisanal and small-scale mining (ASM) sector is a complex and evolving industry that presents unique challenges within the global resource landscape. Despite its traditional labeling as artisanal, ASM operations are increasingly becoming mechanized, utilizing heavy machinery and hazardous chemicals such as mercury and cyanide for mineral extraction. Concurrently, the informal nature of most ASM operations limits effective top-down regulatory enforcements due to governance challenges. These developments have led to wide spreads of degraded, contaminated and abandoned rural community lands which also serve as valuable agricultural and forest lands for inhabitants of affected mining communities. While the existing literature has extensively analyzed the impacts of these developments on local, national, and global economies, ecologies, health, and welfare, there remains a notable gap in understanding the governance of rehabilitating and remediating affected environments post-mineral extraction. Furthermore, phytoremediation – a biological innovation which can help remediate contaminated sites and address the problem of soil degradation and erosion, with reported economic and environmental benefits – has only seen very limited global commercial adoption. In regions where traditional remediation approaches are financially untenable, like in the Global South, however, phytoremediation is argued to be a suitable and viable solution towards a greener future for remediation and environmental restoration. This thesis aims to address the knowledge gaps pertaining to the governance of rehabilitating and remediating affected environments affected by mineral extraction in the artisanal and small-scale mining (ASM) sector. Specifically, it focuses on systematically investigating the governance challenges in ASM, exploring community-based solutions for sustainable land restoration, and proposing a framework for the broader-based application of phytoremediation to address land contamination in the small-scale gold mining sector in Ghana. These research objectives are structured around three chapters, with the first two focusing on empirical case studies and the last chapter serving as a review of scientific and grey literature, as well as project reports on land rehabilitation and phytoremediation. Chapter 2, which addresses the first objective, delves into the obstacles hindering the implementation of the legal framework for artisanal small-scale mining (ASM) in Ghana. The first part conducts an institutional analysis of the legal and political framework governing Ghana’s small scale mining sector, with a particular focus on its implications for post-mined land rehabilitation efforts. This is followed by an assessment of the practical application of the legal framework in the context of small-scale gold mining (ASGM) value chain, using the Process Net-Mapping tool along with stakeholder interviews. The study reveals outdated legislation, formal licensing bureaucracies, land tenure issues, and ineffective collaboration among stakeholders as major bottlenecks. Drawing on these insights, the chapter discusses the broader implications of the findings for the effective running of the ASGM value chain and recommends, among other things, the adoption of collaborative governance systems, like co-management, to ensure sustainability. Chapter 3, which addresses the second objective, examines community-based solutions for sustainable mined land restoration through a case study of an NGO-initiated project in five active mining communities in Ghana's Amansie West district. The chapter utilizes a combination of qualitative methods including the participatory Net-Mapping tool to explore conditions under which local communities would engage in restoration efforts without financial incentives, revealing community support, using communal labor, dependent on factors like land tenure arrangements and local leadership influence. The study underscores the potential of community-led efforts for land rehabilitation, emphasizing the role of social networks, norms, and land tenure structures. Chapter 4, which addresses the third objective, introduces a conceptual framework for the effective and sustainable application of phytoremediation to clean contaminated lands resulting from mining activities. This is the result of insights drawn from existing phytoremediation literature, including case studies where the field application or/and commercialization of phytoremediation has been successful, and lessons gleaned from other real-world applications of the technology. The framework encompasses technical considerations across the phytoremediation process and identifies the socio-cultural, economic, political, and institutional conditions necessary for successful large-scale implementation. The paper provides valuable guidance for regions seeking to leverage phytoremediation to benefit society and the environment. In conclusion, this thesis contributes to understanding the challenges facing the ASM sector and proposes innovative solutions to address governance issues, promote community-based land restoration, and facilitate the scaling of phytoremediation initiatives for sustainable development in the mining sector, particularly in developing regions. The holistic approach advocated in this thesis underscores the importance of legal reforms tailored to the constantly evolving ASM sector, stakeholder collaboration, adaptive governance systems, and community engagement to effectively navigate the intricate ASM landscape and maximize its beneficial effects on local livelihoods and development worldwide.
Do regional-specific differences influence smallholder farmers’ climate information use? Evidence from Ghana
(2025) Owusu, Victor; Asravor, Jacob
Mounting evidence underscores the importance of improving smallholder farmers’ use of reliable climate information (CI) in sub-Saharan Africa (SSA). Previous studies have not examined the differences in region-specific climate information use, as well as predictors of the source, type and timing of climate information use. In this study, we provide empirical evidence on how location-specific differences influence the source, type and timing of CI use. Integrating cross-sectional data from 503 households in the Upper West Region (UWR) and Brong-Ahafo Region (BAR) of Ghana into a multivariate probit model, our results indicate that farm households in the two regions exhibit different preferences regarding the source, type and timing of CI use. We find that while households in the BAR are more interested in CI ahead of the season – given that rainfall is relatively secure in that region, CI use ahead of the season is of less interest to those in the UWR where rainfall is more erratic. Our results further show that while CI source, type and timing are considerably influenced by education, distance to the farm, access to credit and extension in the UWR, gender, farm size, education and tractor access tend to drive the source, type and timing of CI use in BAR. These findings underscore the need for a more downscaled and context-specific strategy in disseminating CI services in the various regions of SSA. Practical implications: Notwithstanding evidence that the adverse impacts of the changing climate on smallholder livelihoods continue to vary within and across communities, districts, regions and agro-ecological zones (Abbam et al., 2018) in sub-Saharan Africa, little is known about how location-specific distinctions in climate change impact, infrastructural endowments as well as socioeconomic and plot-level attributes of smallholder farmers influence farm households’ use of climate information (CI). Given that these location-specific distinctions can considerably influence the generation and dissemination of CI, and its subsequent uptake by farm households in various regions, the empirical findings from this study are relevant for policy formulation towards boosting the use of CI. Evidence from this study strongly suggests that the diverse locations of smallholder farmers tend to significantly influence the source, type and period of CI use; for example, farm households in the Brong-Ahafo Region, a relatively more infrastructurally developed region, have better prospects of accessing different types of CI from diverse sources. We further find that the period of the cropping season in which CI is used is considerably influenced by the location of the farmers; and we identify disparities in the plot-level, institutional and socioeconomic characteristics of rural households in these two study regions that significantly influence the types, sources and times of CI used by farm households. Consequently, there is a need to take into account the unique regional, agro-ecological, plot-level, institutional and socioeconomic attributes of farm households. Policy recommendations on CI use should be tailored to the needs of these specific locations rather than being wholesale. Investment in rural infrastructure may trigger economic opportunities in deprived regions such as the Upper West Region. This may motivate rural households in such regions to invest in different CI types and sources for enhanced uptake of climate information.
Legume-derived phenolic acids influence Fusarium oxysporum f.sp. strigae compatibility and biocontrol potential in a Striga push–pull system
(2025) Assena, Mekuria Wolde; Schöne, Jochen; Rasche, Frank
Biological control of Striga hermonthica (Del.) Benth. includes push–pull, intercropping using legumes, and soil-borne fungi such as Fusarium oxysporum f.sp. strigae (FOS). Efficacy of both technologies is compromised by various environmental factors. Combining them could potentially overcome their limitations and enhance control of S. hermonthica. It was hypothesized that FOS inoculation is compatible with push–pull intercropping, allowing consistent S. hermonthica suppression. Effects of selected phenolic acids and crude root exudates from three legume species (Mucuna pruriens, Desmodium uncinatum, Crotalaria juncea) on FOS mycelial growth and spore germination were studied. Bioassays showed that most phenolic acids (e.g., caffeic, p-hydroxybenzoic, syringic) had no effect on FOS development, except for piperonylic (80 %, 38 %) and t-cinnamic (53 %, 33 %) acids, which strongly inhibited growth at concentrations of 1 and 0.5 mM, respectively. Crude root exudates from Crotalaria inhibited FOS mycelial growth at 1 (44 %) and 0.5 (32 %) mg ml-1. Desmodium and Mucuna exudates showed no inhibition. Greenhouse results showed that legume intercropping and FOS inoculation reduced S. hermonthica emergence, with their integration achieving over 95 % suppression and boosting maize biomass. Legume presence enhanced FOS proliferation, with Mucuna and Desmodium increasing FOS gene copy numbers by over 44 %. LC-MS analysis identified nine phenolic acids, with p-coumaric (85–128 µg g−1) and p-hydroxybenzoic (50–97 µg g−1) acid being most abundant; the latter positively correlated with FOS abundance. In this setting, legume intercropping with maize did not impair FOS proliferation in rhizosphere soil and effectively suppressed S. hermonthica, demonstrating compatibility of FOS inoculation with push–pull for effective S. hermonthica management.
Diacetoxyscirpenol, a Fusarium exometabolite, prevents efficiently the incidence of the parasitic weed Striga hermonthica
(2022) Anteyi, Williams Oyifioda; Klaiber, Iris; Rasche, Frank; Anteyi, Williams Oyifioda; Institute of Agricultural Sciences in the Tropics (Hans-Ruthenberg-Institute), University of Hohenheim, Stuttgart, Germany; Klaiber, Iris; Core Facility Hohenheim, University of Hohenheim, Stuttgart, Germany; Rasche, Frank; Institute of Agricultural Sciences in the Tropics (Hans-Ruthenberg-Institute), University of Hohenheim, Stuttgart, Germany
Background: Certain Fusarium exometabolites have been reported to inhibit seed germination of the cereal-parasitizing witchweed, Striga hermonthica , in vitro . However, it is unknown if these exometabolites will consistently prevent S. hermonthica incidence in planta . The study screened a selection of known, highly phytotoxic Fusarium exometabolites, in identifying the most potent/efficient candidate (i.e., having the greatest effect at minimal concentration) to completely hinder S. hermonthica seed germination in vitro and incidence in planta , without affecting the host crop development and yield. Results: In vitro germination assays of the tested Fusarium exometabolites (i.e., 1,4-naphthoquinone, equisetin, fusaric acid, hymeglusin, neosolaniol (Neo), T-2 toxin (T-2) and diacetoxyscirpenol (DAS)) as pre- Striga seed conditioning treatments at 1, 5, 10, 20, 50 and 100 µM, revealed that only DAS, out of all tested exometabolites, completely inhibited S. hermonthica seed germination at each concentration. It was followed by T-2 and Neo, as from 10 to 20 µM respectively. The remaining exometabolites reduced S. hermonthica seed germination as from 20 µM ( P < 0. 0001). In planta assessment (in a S. hermonthica -sorghum parasitic system) of the exometabolites at 20 µM showed that, although, none of the tested exometabolites affected sorghum aboveground dry biomass ( P > 0.05), only DAS completely prevented S. hermonthica incidence. Following a 14-d incubation of DAS in the planting soil substrate, bacterial 16S ribosomal RNA (rRNA) and fungal 18S rRNA gene copy numbers of the soil microbial community were enhanced; which coincided with complete degradation of DAS in the substrate. Metabolic footprinting revealed that the S. hermonthica mycoherbicidal agent, Fusarium oxysporum f. sp. strigae (isolates Foxy-2, FK3), did not produce DAS; a discovery that corresponded with underexpression of key genes (Tri5, Tri4) necessary for Fusarium trichothecene biosynthesis ( P < 0.0001). Conclusions: Among the tested Fusarium exometabolites, DAS exhibited the most promising herbicidal potential against S. hermonthica . Thus, it could serve as a new biocontrol agent for efficient S. hermonthica management. Further examination of DAS specific mode of action against the target weed S. hermonthica at low concentrations (≤ 20 µM), as opposed to non-target soil organisms, is required.
Arbuscular mycorrhizal fungi-based bioremediation of mercury: insights from zinc and cadmium transporter studies
(2023) Guo, Yaqin; Martin, Konrad; Hrynkiewicz, Katarzyna; Rasche, Frank; Guo, Y.; Faculty of Agricultural Sciences, Institute of Agricultural Sciences in the Tropics (Hans-Ruthenberg-Institute), University of Hohenheim, 70593, Stuttgart, Germany; Martin, K.; Faculty of Agricultural Sciences, Institute of Agricultural Sciences in the Tropics (Hans-Ruthenberg-Institute), University of Hohenheim, 70593, Stuttgart, Germany; Hrynkiewicz, K.; Department of Microbiology, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University, 87-100, Torun, Poland; Rasche, F.; Faculty of Agricultural Sciences, Institute of Agricultural Sciences in the Tropics (Hans-Ruthenberg-Institute), University of Hohenheim, 70593, Stuttgart, Germany
Phytoremediation, a sustainable approach for rehabilitating mercury (Hg)-contaminated soils, can be enhanced by arbuscular mycorrhizal (AM) fungi, which promote plant growth and metal uptake, including Hg, in contaminated soils. Hg, despite lacking a biological function in plants, can be absorbed and translocated using Zn and/or Cd transporters, as these elements belong to the same group in the periodic table (12/2B). In fact, the specific transporters of Hg in plant roots remain unknown. This study is therefore to provide fundamental insights into the prospect to remediate Hg-contaminated soils, with a focus on the role of AM fungi. The hypothesis posits that Hg uptake in plants may be facilitated by transporters responsible for Zn/Cd, affected by AM fungi. The Scopus database was used to collect studies between 2000 and 2022 with a focus on the ecological role of AM fungi in environments contaminated with Zn and Cd. Particular emphasis was laid on the molecular mechanisms involved in metal uptake and partitioning. The study revealed that AM fungi indeed regulated Zn and/or Cd transporters, influencing Zn and/or Cd uptake in plants. However, these effects vary significantly based on environmental factors, such as plant and AM fungi species and soil conditions (e.g., pH, phosphorus levels). Given the limited understanding of Hg remediation, insights gained from Zn and Cd transporter systems can guide future Hg research. In conclusion, this study underscores the importance of considering environmental factors and provides fundamental insights into the potential of Hg phytoremediation with the assistance of AM fungi.
Do we need post-tree thinning management? Prescribed fire and goat browsing to control woody encroacher species in an Ethiopian savanna
(2024) Abate, Teshome; Abebe, Tesfaye; Treydte, Anna; Abate, Teshome; College of Agriculture, Hawassa University, Hawassa, Ethiopia; Abebe, Tesfaye; College of Agriculture, Hawassa University, Hawassa, Ethiopia; Treydte, Anna; Department of Sustainable Agriculture and Biodiversity Conservation, The Nelson Mandela African Institution of Science and Technology, Arusha, Tanzania
Worldwide, bush encroachment threatens rangeland ecosystem services, including plant biodiversity and forage for livestock. Various control methods for encroaching woody species and restoring herbaceous vegetation exist but have rarely been explored experimentally. We assessed the impact of post-tree thinning management on tree mortality, the herbaceous community, and overall rangeland condition in Borana, an Ethiopian savanna ecosystem. At two 1.4 ha areas of encroached mono-specific Vachellia drepanolobium (whistling thorn) stands, we set up twenty-four 20 × 10 m experimental plots with four post-tree-thinning treatments (goat browsing only (1), prescribed fire (2), fire and goat browsing (3), and control (4) (i.e., no management after tree cutting), with three replications in a complete block design. Over two growing periods, we monitored resulting tree mortality, coppicing, seedling mortality and recruitment, as well as herbaceous layer attributes (diversity, biomass) and overall rangeland condition. All three post-tree thinning management scenarios significantly enhanced tree mortalities, reduced seedling recruitment and increased the abundance of the dominant desirable grass species. Prescribed fire and fire and goat-browsing treatments resulted in significantly greater grass and forb species richness, forb diversity, and biomass, as well as the overall rangeland condition compared to goat browsing only and the control treatment. However, grass species diversity did not respond to treatments. Post-tree management significantly increased tree mortality, reduced seedling recruitment, and increased the abundance of desirable grass species. Our findings strongly suggest that post-thinning management, particularly prescribed fire or a combination of fire and browsing, is highly effective in suppressing woody encroachment and improving biomass and overall rangeland condition.
Modelling nitrogen use and excretion in dairy cattle herds grazing temperate, semi-natural grasslands
(2025) Perdana-Decker, Sari; Dickhöfer, Uta
Grazing-based dairy cattle systems exhibit several benefits, such as preserving biodiverse grassland habitats, improving animal welfare, or turning grassland protein into human-edible protein. However, grazing-based diets are prone to greater nitrogen (N) losses via urine than balanced stall-fed diets, leading to a greater risk for N emissions. Strategies for improving the N use in grazing-based systems are predominantly investigated on homogenous clover-ryegrass pastures with high yields and nutritional quality. In contrast, grazing-based systems reliant on less external inputs (e.g., synthetic fertilisers or concentrates) using semi-natural grassland as main feed source received less attention. The present thesis addressed the knowledge gap on the N use of such low-input grazing-based systems by adapting an existing dynamic, process-based herd model (i.e., the LIVestock SIMulator, LIVSIM) for simulating animal performance and N use and excretion of dairy herds. For this, a broad dataset was gathered on nine commercial organic dairy cattle farms in Baden-Württemberg during two grazing periods (2019, 2020). This dataset fulfilled two purposes: firstly, to get a basic understanding on N use and excretion of dairy cows under low-input grazing conditions (study 1); secondly, to serve as reference dataset for adapting and evaluating LIVSIM for such production systems (studies 2 and 3). The reference dataset represented the wide range of grazing and production factors found on commercial farms in South Germany using semi-natural grasslands for grazing. The dataset applied for study 1 covered n = 323 individual animal observations with mean (± one standard deviation) milk production, dry matter intake (DMI), and pasture DMI (PDMI) of 23.9 (± 5.35), 21.0 (± 3.21), and 11.3 (± 4.83) kg/d, respectively. Milk N use efficiency (MNE) averaged 24.7 g/100 g N intake (± 5.91), which is greater than observations in temperate, high-input grazing-based systems but lower than in cows receiving balanced stall-fed diets. Nevertheless, MNE and other indicators of N use and excretion varied greatly among farms and seasons, highlighting the need to identify the drivers for this variation. Supplement feeding had the greatest potential for manipulating the N use and excretion. Increasing shares of fresh forages as well as of hay of total supplement DMI increased N use (e.g., MNE) and decreased urinary N excretion (e.g., urinary N to creatinine ratio), while increasing shares of concentrates of supplement DMI were related to lower N losses via urine. Study 1 highlighted that using semi-natural grasslands for grazing can potentially reduce environmentally harmful N losses compared to high-input grazing systems. For future research endeavours, a modelling approach may simplify the investigation of more feeding scenarios, their interactions, different local conditions, and considering the spatial and temporal variation of pasture herbage quality and yield. Hence, studies 2 and 3 focused on adaptating LIVSIM for low-input grazing-based dairy farms. The DMI and N intake are among the most decisive factors for determining animal performance and N excretion. Therefore, a module for predicting the PDMI of cows grazing semi-natural grassland was identified in study 2, using a subset of the reference dataset (n = 233 individual animal observations). Among the thirteen tested models, behaviour-based and semi-mechanistic models specifically developed for grazing animals had the lowest prediction adequacy. Their underlying empirical equations likely did not fit the grazing and production conditions of farms employing semi-natural grasslands. Modelling performance of a semi-mechanistic model developed for stall-based feeding situations (Mertens II) with slight modifications was best (relative prediction error = 13.4%) when evaluated based on the mean observed PDMI (i.e., averaged across animals per farm and period (n = 28)). Consequently, the modified Mertens II model was integrated in LIVSIM in study 3. Additionally, the modules for energy requirements, lactation, N excretion, and herd management were adopted, and breed-specific model coefficients added to represent Simmental, Brown Swiss, and Holstein-Friesian cattle breeds. Dairy cow characteristics, herd composition, annual milk yield, and DMI were predicted accurately (i.e., with a relative difference ≤ 10 % between observed and predicted outputs for the majority of outputs). The absolute total N excretion (g/d) was underpredicted by 23 % (= relative difference between observed and predicted values) mainly due to the underprediction of urinary N excretion by 43 %. The relative differences in N excretion between farming systems, in contrast, were predicted reliably. The observed faecal, urinary, and total N excretion (in % of N intake) differed by 30, -23, and -7 %, respectively, between the two reference herds, which is similar to the respective relative differences for the predicted faecal, urinary, and total N excretion of 32, -36, and -4 %. Further model improvements should focus on increasing the prediction accuracy of N excretion and its partitioning due to the varying degree of susceptibility of faecal or urinary N to volatilisation and leaching. The scenario and sensitivity analyses further confirmed that the adapted LIVSIM plausibly simulated differences in animal performance and nutrient excretions based on differences in supplement feeds and pasture herbage. Core input and model coefficients are the dietary ME, CP, and rumen-undegradable CP concentrations, as well as the available herbage biomass on pastures, for which precise measurements are thus needed. The findings of studies 2 and 3 demonstrate that existing models can be adopted for low-input grazing-based dairy production systems. There is further potential for adapting LIVSIM for production systems beyond the ones investigated in the present study, and/or for adding more outputs (e.g., enteric methane) and scales (e.g., grassland) to better capture the multifaceted aspects determining farm sustainability.
Exploring the plausibility of inoculated cowpeas as a climate adaptation strategy for Namibian smallholder farmers
(2025) Rasche, Livia; Katjana, Johannes; Jantke, Kerstin; Uchezuba, David; Schneider, Uwe A.; Rasche, Livia; Research Unit Sustainability and Climate Risks, Center for Earth System Research and Sustainability (CEN), Universität Hamburg, 20144 Hamburg, Germany; Katjana, Johannes; School of Agriculture and Natural Resource Sciences, Namibia University of Science and Technology, Windhoek 10005, Namibia; Jantke, Kerstin; Research Unit Sustainability and Climate Risks, Center for Earth System Research and Sustainability (CEN), Universität Hamburg, 20144 Hamburg, Germany; Uchezuba, David; School of Agriculture and Natural Resource Sciences, Namibia University of Science and Technology, Windhoek 10005, Namibia; Schneider, Uwe A.; Research Unit Sustainability and Climate Risks, Center for Earth System Research and Sustainability (CEN), Universität Hamburg, 20144 Hamburg, Germany; Lombardi, Mariarosaria
Increased cultivation of cowpeas is a possible adaptation option for Namibian farmers under changing climatic conditions. Using inoculated cowpeas can potentially double the yields under favorable climate conditions. But is such a potentially beneficial agricultural adaptation technique likely to be adopted? We surveyed 90 cowpea farmers from 30 villages in the Kavango region of northern Namibia on their households and farms, access to institutions and services, food consumption and preferences, and perceptions of climate change. Our survey reveals that smallholder farmers will not readily adopt the new technology. At most, about 50% of farmers can be convinced by new information to change their agricultural activities. When specifically asked about their willingness to grow inoculated cowpeas, almost all farmers responded that they would be willing to do so. However, the farmers are reluctant to allocate more land for cowpea cultivation, mainly because harvesting is very time and labor-intensive. The study shows that technology assessments should be conducted in combination with socio-economic assessments to realistically assess the potential success of proposed adaptation measures, as the extent to which a new technology may be adopted is an essential indicator for justifying funding of new technologies or adaptation programs.
Scenario analysis of global food security within CGE models: The role of caloric equivalents
(2023) Korovin, Vladimir; Boysen-Urban, Kirsten
In the last decade, the topic of food security attracted significant attention from the research community, politicians, and the general public. This is not surprising, as every person should have a guaranteed physical and economic access to safe, nutritious and a sufficient amount of food all year round. Including the aim to eradicate all forms of malnutrition, each of these food security elements is an integral part of the agenda for Sustainable Development defined by the UN in 2015. Nonetheless, full achievement of the agenda’s ambitious goals is far from being easy in the near future. On the contrary, recent years have shown an increasing number of undernourished people around the globe. This is certainly a worrying sign. The future socio-economic development, rising population, resource scarcity, changing demand patterns, diminishing increase of agricultural yields; each of these aspects further exacerbate the uncertainty of food security. They underline how important it is to assess the prospect challenges to feeding the world. Within the broad spectrum of methodological approaches used for projection studies, the computable general equilibrium (CGE) models occupy a strong position. However, as CGE models are essentially economic models and use monetary indexes by default, the direct application of CGE models for the evaluation as well as communicating results on dietary and food security issues remains fundamentally challenging. With this in mind, this thesis provides a state-of-the-art overview on the design and implementation of the forward-looking exercises within the CGE modeling framework with an explicit focus on food and nutrition security. As a part of this work, the author elaborates whether and how caloric equivalents can be included in CGE models, underlining their relevance for the modeling framework in general, as well as defining plausible scenarios for the future global and regional food security trajectories in particular. The centerpiece of this thesis is a comprehensive modeling framework that is capable of analyzing the development of future regional food security and facilitating discussions on various aspects of long-term projections within CGE models. An important element of this framework is the integrated calorie module that contributes to the reporting as well as the validation of the model’s results. The empirical analysis conducted with the help of this extended modeling framework underlines the importance of such caloric metrics and identifies benefits of their application in scenario analysis. It also shows the advantages for intercomparison of modeling outcomes at the stage of sensitivity analysis as well as across different studies. The simulation results reveal the potential for further elevation of the average consumer’s energy intake in all regions under the central scenarios. However, the expected increase in calorie availability is neither regionally uniform nor scenario specific. Some regions do not show a substantial improvement in energy intake though, indicating that a substantial share of their population could remain food insecure. Both central scenarios emphasize a tendency in emerging and industrialized countries toward more energy-dense diets, containing more animal-based products, sugars, and oils. This, in turn, imposes the risk of unbalanced diets and overconsumption. This thesis and the presented method of integrating caloric information into the CGE model provides a solid basis for further research. It makes a substantial contribution to the discussion of scenario analyses and application of CGE models in the area of food security modeling. In this regard, the calorie module has proven itself to be a valuable diagnostic tool and a central element for food security assessment. The approach of integrating caloric equivalents presented in this work is very general and can easily be extended to include other macronutrients, such as fats, proteins, and carbohydrates. The free accessibility of the data sources used and the transparent implementation process are evident strengths of the approach that might further motivate its use. Moreover, the proposed modeling framework offers an interesting and effective tool for analyzing various research questions concerning dietary trajectories and food security policies in long-term scenario analyses. The study of policy mechanisms targeting the adverse developments of dietary shifts might be one such interesting research direction.
Win-win opportunities combining high yields with high multi-taxa biodiversity in tropical agroforestry
(2022) Wurz, Annemarie; Tscharntke, Teja; Martin, Dominic Andreas; Osen, Kristina; Rakotomalala, Anjaharinony A. N. A.; Raveloaritiana, Estelle; Andrianisaina, Fanilo; Dröge, Saskia; Fulgence, Thio Rosin; Soazafy, Marie Rolande; Andriafanomezantsoa, Rouvah; Andrianarimisa, Aristide; Babarezoto, Fenohaja Soavita; Barkmann, Jan; Hänke, Hendrik; Hölscher, Dirk; Kreft, Holger; Rakouth, Bakolimalala; Guerrero-Ramírez, Nathaly R.; Ranarijaona, Hery Lisy Tiana; Randriamanantena, Romual; Ratsoavina, Fanomezana Mihaja; Raveloson Ravaomanarivo, Lala Harivelo; Grass, Ingo; Wurz, Annemarie; Conservation Ecology, Department of Biology, Philipps-University Marburg, Marburg, Germany; Tscharntke, Teja; Centre for Biodiversity and Sustainable Land Use (CBL), University of Göttingen, Göttingen, Germany; Martin, Dominic Andreas; Department of Geography, University of Zurich, Zürich, Switzerland; Osen, Kristina; Tropical Silviculture and Forest Ecology, University of Göttingen, Göttingen, Germany; Rakotomalala, Anjaharinony A. N. A.; Entomology Department Faculty of Science, University of Antananarivo, Antananarivo, Madagascar; Raveloaritiana, Estelle; Plant Biology and Ecology Department, University of Antananarivo, University of Antananarivo, Antananarivo, Madagascar; Andrianisaina, Fanilo; Department of Tropical Agriculture and Sustainable Development, Higher School of Agronomic Science,University of Antananarivo, Antananarivo, Madagascar; Dröge, Saskia; Division of Forest, Nature and Landscape, KU Leuven, Leuven, Belgium; Fulgence, Thio Rosin; Natural and Environmental Sciences, Regional University Centre of the SAVA Region (CURSA), Antalaha, Madagascar; Soazafy, Marie Rolande; Doctoral School of Natural Ecosystems (EDEN), University of Mahajanga, Mahajanga, Madagascar; Andriafanomezantsoa, Rouvah; Zoology and Animal Biodiversity, Faculty of Sciences, University of Antananarivo, Antananarivo, Madagascar; Andrianarimisa, Aristide; Zoology and Animal Biodiversity, Faculty of Sciences, University of Antananarivo, Antananarivo, Madagascar; Babarezoto, Fenohaja Soavita; Diversity Turn in Land Use Science, coordination office, Sambava, Madagascar; Barkmann, Jan; Department of Agricultural Economics and Rural Development, Research Unit Environmental- and Resource Economics, University of Göttingen, Göttingen, Germany; Hänke, Hendrik; Department of Agricultural Economics and Rural Development, Research Unit Environmental- and Resource Economics, University of Göttingen, Göttingen, Germany; Hölscher, Dirk; Tropical Silviculture and Forest Ecology, University of Göttingen, Göttingen, Germany; Kreft, Holger; Biodiversity, Macroecology and Biogeography, University of Göttingen, Göttingen, Germany; Rakouth, Bakolimalala; Plant Biology and Ecology Department, University of Antananarivo, University of Antananarivo, Antananarivo, Madagascar; Guerrero-Ramírez, Nathaly R.; Biodiversity, Macroecology and Biogeography, University of Göttingen, Göttingen, Germany; Ranarijaona, Hery Lisy Tiana; Doctoral School of Natural Ecosystems (EDEN), University of Mahajanga, Mahajanga, Madagascar; Randriamanantena, Romual; Natural and Environmental Sciences, Regional University Centre of the SAVA Region (CURSA), Antalaha, Madagascar; Ratsoavina, Fanomezana Mihaja; Zoology and Animal Biodiversity, Faculty of Sciences, University of Antananarivo, Antananarivo, Madagascar; Raveloson Ravaomanarivo, Lala Harivelo; Entomology Department Faculty of Science, University of Antananarivo, Antananarivo, Madagascar; Grass, Ingo; Ecology of Tropical Agricultural Systems, University of Hohenheim, Stuttgart, Germany
Resolving ecological-economic trade-offs between biodiversity and yields is a key challenge when addressing the biodiversity crisis in tropical agricultural landscapes. Here, we focused on the relation between seven different taxa (trees, herbaceous plants, birds, amphibians, reptiles, butterflies, and ants) and yields in vanilla agroforests in Madagascar. Agroforests established in forests supported overall 23% fewer species and 47% fewer endemic species than old-growth forests, and 14% fewer endemic species than forest fragments. In contrast, agroforests established on fallows had overall 12% more species and 38% more endemic species than fallows. While yields increased with vanilla vine density and length, non-yield related variables largely determined biodiversity. Nonetheless, trade-offs existed between yields and butterflies as well as reptiles. Vanilla yields were generally unrelated to richness of trees, herbaceous plants, birds, amphibians, reptiles, and ants, opening up possibilities for conservation outside of protected areas and restoring degraded land to benefit farmers and biodiversity alike.
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; Heintze, Sebastian; Fraunhofer Institute for Interfacial Engineering and Biotechnology, Nobelstr. 12, 70569 Stuttgart, Germany; (S.H.); (L.S.K.); Beckett, Marc; Fraunhofer Institute for Interfacial Engineering and Biotechnology, Nobelstr. 12, 70569 Stuttgart, Germany; (S.H.); (L.S.K.); Kriem, Lukas Simon; Fraunhofer Institute for Interfacial Engineering and Biotechnology, Nobelstr. 12, 70569 Stuttgart, Germany; (S.H.); (L.S.K.); Germer, Jörn; Hans-Ruthenberg Institute for Tropical Agricultural Sciences, University of Hohenheim, Garbenstr. 13, 70599 Stuttgart, Germany; (J.G.); (F.A.); Asch, Folkard; Hans-Ruthenberg Institute for Tropical Agricultural Sciences, University of Hohenheim, Garbenstr. 13, 70599 Stuttgart, Germany; (J.G.); (F.A.); 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.
Made in Africa – how to make local agricultural machinery manufacturing thrive
(2024) Daum, Thomas; Adegbola, Ygué Patrice; Kamau, Geoffrey; Kergna, Alpha Oumar; Daudu, Christogonus; Adebowale, Wahab Akeem; Adegbola, Carine; Bett, Charles; Mulinge, Wellington; Zossou, Roch Cedrique; Nientao, Abdoulaye; Kirui, Oliver; Oluwole, Fatunbi Abiodun
Manufacturing has the potential to drive economic growth, job creation and poverty reduction, but African manufacturers face challenges in competing with global markets. Agricultural machinery manufacturing may be one niche where African manufacturers can succeed. This paper examines the challenges and opportunities facing local agricultural manufacturers in Africa based on a survey of 386 manufacturers in four countries and qualitative methods. Results show that small, dedicated entrepreneurs have created vibrant local machinery markets. These manufacturers have several comparative advantages, in particular, the ability to develop machinery adapted to local agroecological conditions but face challenges related to financing, human resources, utilities, raw materials, production equipment and the regulatory environment. The paper offers recommendations on how to support local manufacturers to make “Made in Africa” the first choice for African farmers and agro-food processors.

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