Institut für Tropische Agrarwissenschaften (Hans-Ruthenberg-Institut)

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Arbuscular mycorrhizal fungi-based bioremediation of mercury: insights from zinc and cadmium transporter studies
(2023) Guo, Yaqin; Martin, Konrad; Hrynkiewicz, Katarzyna; Rasche, Frank
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.
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; Gutai, Benjamin; Institute of Agricultural Sciences in the Tropics (Hans-Ruthenberg-Institute), University of Hohenheim, Garbenstr. 13, 70599, Stuttgart, Germany; Marohn, Carsten; Institute of Agricultural Sciences in the Tropics (Hans-Ruthenberg-Institute), University of Hohenheim, Garbenstr. 13, 70599, Stuttgart, Germany; Bateki, Christian Adjogo; Section Animal Husbandry in the Tropics and Subtropics, University of Kassel and University of Göttingen, Steinstr. 19, 37213, Witzenhausen, Germany; Asch, Folkard; Institute of Agricultural Sciences in the Tropics (Hans-Ruthenberg-Institute), University of Hohenheim, Garbenstr. 13, 70599, Stuttgart, Germany
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.
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.
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; 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.
Complementary ecosystem services from multiple land uses highlight the importance of tropical mosaic landscapes
(2023) Raveloaritiana, Estelle; Wurz, Annemarie; Osen, Kristina; Soazafy, Marie Rolande; Grass, Ingo; Martin, Dominic Andreas; Bemamy, Claudine; Ranarijaona, Hery Lisy Tiana; Borgerson, Cortni; Kreft, Holger; Hölscher, Dirk; Rakouth, Bakolimalala; Tscharntke, Teja
Tropical agricultural landscapes often consist of a mosaic of different land uses, yet little is known about the spectrum of ecosystem service bundles and materials they provide to rural households. We interviewed 320 households on the different benefits received from prevalent land-use types in north-eastern Madagascar (old-growth forests, forest fragments, vanilla agroforests, woody fallows, herbaceous fallows, and rice paddies) in terms of ecosystem services and plant uses. Old-growth forests and forest fragments were reported as important for regulating services (e.g. water regulation), whilst fallow lands and vanilla agroforests as important for provisioning services (food, medicine, fodder). Households reported the usage of 285 plant species (56% non-endemics) and collected plants from woody fallows for varying purposes, whilst plants from forest fragments, predominantly endemics, were used for construction and weaving. Multiple land-use types are thus complementary for providing ecosystem services, with fallow lands being particularly important. Hence, balancing societal needs and conservation goals should be based on diversified and comprehensive land management.
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
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.
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.; 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.
Guidelines for improved quantification and reporting of carbon stocks and additional carbon storage in agroforestry systems
(2025) Cardinael, Rémi; Cadisch, Georg; Dupraz, Christian; Lojka, Bohdan; Oelbermann, Maren
The number of scientific publications related to biomass carbon or soil organic carbon under various land management practices has globally and dramatically increased during the last two decades, the same applies to the peer reviewed Agroforestry Systems journal. However, the quality of papers on carbon sequestration in agroforestry systems is very heterogeneous, and many studies do not fulfil simple requirements that would ensure the scientific value of these studies, resulting in high rates of rejections before and after review. The aim of this paper, co-authored by the Editor-in-Chief and Associate Editors of the Agroforestry Systems journal is to provide some basic guidelines to improve the quantification and reporting of carbon stocks and additional carbon storage in agroforestry systems, and to maximize manuscript acceptance. These guidelines are also of use for any other international peer-reviewed journal publishing studies on this topic. We also provide a checklist, for both authors and reviewers, of compulsory and recommended variables to be included before submission of an original study related to soil and/or biomass carbon stocks and sequestration in agroforestry systems.
Influence of climate-smart technologies on the success of livestock donation programs for smallholder farmers in Rwanda
(2024) Kandulu, John M.; Zuo, Alec; Wheeler, Sarah; Dusingizimana, Theogene; Chagunda, Mizeck G. G.; Kandulu, John M.; School of Economics and Public Policy, The University of Adelaide, 10 Pulteney St, 5005, Adelaide, South Australia, Australia; Zuo, Alec; School of Economics and Public Policy, The University of Adelaide, 10 Pulteney St, 5005, Adelaide, South Australia, Australia; Wheeler, Sarah; School of Economics and Public Policy, The University of Adelaide, 10 Pulteney St, 5005, Adelaide, South Australia, Australia; Dusingizimana, Theogene; College of Agriculture, Animal Science and Veterinary Medicine, University of Rwanda, P.O. Box 210, Musanze, Kigali, Rwanda; Chagunda, Mizeck G. G.; Animal Breeding and Husbandry in the Tropics and Subtropics, University of Hohenheim, Garben Street, 17 Instituts- Und Hörsaalgebäude, -112, Stuttgart, Germany
Climate change threatens the livelihoods of Sub-Saharan African farmers through increased droughts. Livestock donation programs offer a potential solution, but their effectiveness under climate stress remains unclear. This study assesses the economic viability of integrating climate-smart technologies (cowsheds and biogas plants) into these programs in Rwanda. Using a stochastic benefit–cost analysis from the beneficiary perspective, we evaluate the net gains for households receiving heifers compared to the current program. Our findings reveal that integrating climate-smart technologies significantly enhances economic viability. Households with cows and climate-smart technologies can possibly realise net benefits 3.5 times higher than the current program, with benefit–cost ratios reaching 5:1. Beyond economic benefits, adopting biogas reduces deforestation, greenhouse gas emissions, and respiratory illness risks. This study demonstrates that integrating climate-smart technologies into livestock donation programs can generate positive economic, environmental, and health benefits, leading to more resilient and sustainable smallholder systems. However, overcoming implementation challenges requires tailored policy packages addressing local barriers.
Monitoring soil carbon in smallholder carbon projects: insights from Kenya
(2024) Okoli, Adaugo O.; Birkenberg, Athena; Okoli, Adaugo O.; Department of Social and Institutional Change in Agricultural Development, Hans-Ruthenberg-Institute of Agricultural Science in the Tropics, University of Hohenheim, Wollgrasweg 43, 70599, Stuttgart, Germany; Birkenberg, Athena; Department of Social and Institutional Change in Agricultural Development, Hans-Ruthenberg-Institute of Agricultural Science in the Tropics, University of Hohenheim, Wollgrasweg 43, 70599, Stuttgart, Germany
Voluntary carbon market schemes facilitate funding for projects promoting sustainable land management practices to sequester carbon in natural sinks such as biomass and soil, while also supporting agricultural production. The effectiveness of VCM schemes relies on accurate measurement mechanisms that can directly attribute carbon accumulation to project activities. However, measuring carbon sequestration in soils has proven to be difficult and costly, especially in fragmented smallholdings predominant in global agriculture. The cost and accuracy limitations of current methods to monitor soil organic carbon (SOC) limit the participation of smallholder farmers in global carbon markets, where they could potentially be compensated for adopting sustainable farming practices that provide ecosystem benefits. This study evaluates nine different approaches for SOC accounting in smallholder agricultural projects. The approaches involve the use of proximal and remote sensing, along with process models. Our evaluation centres on stakeholder requirements for the Measurement, Reporting, and Verification system, using the criteria of accuracy, level of standardisation, costs, adoptability, and the advancement of community benefits. By analysing these criteria, we highlight opportunities and challenges associated with each approach, presenting suggestions to enhance their applicability for smallholder SOC accounting. The contextual foundation of the research is a case study on the Western Kenya Soil Carbon Project. Remote sensing shows promise in reducing costs for direct and modelling-based carbon measurement. While it is already being used in certain carbon market applications, transparency is vital for broader integration. This demands collaborative work and investment in infrastructure like spectral libraries and user-friendly tools. Balancing community benefits against the detached nature of remote techniques is essential. Enhancing information access aids farmers, boosting income through improved soil and crop productivity, even with remote monitoring. Handheld sensors can involve smallholders, given consistent protocols. Engaging the community in monitoring can cut project costs, enhance agricultural capabilities, and generate extra income.
Mungbean response to regulated deficit irrigation: a trade‐off between productivity and adaptability?
(2025) Pataczek, Lisa; Hakenberg, Tim; Hilger, Thomas; Nair, Ramakrishnan M.; Schafleitner, Roland; Asch, Folkard; Cadisch, Georg
Water scarcity, elevated temperatures, as well as pests and diseases have been demonstrated to have a detrimental effect on the yield potential of mungbean ( Vigna radiata ). The cultivation of improved mungbean genotypes with regulated deficit irrigation (RDI), a water‐saving irrigation strategy, has been identified as a promising approach to enhance yield stability of the crop and ensure food security. Thus, the purpose of this study was to identify adaptation strategies and possible trade‐offs to drought of mungbean genotypes under deficit irrigation and the effect on yield by investigating in particular assimilate re‐allocation. Four genotypes (NM11, AVMU 1604, AVMU 1635, KPS2) were cultivated in a greenhouse under three treatments of RDI with depletion fractions as a percentage of total available soil water (TAW) of 0.45, 0.65, and 0.8, corresponding to a recommended irrigation schedule, moderate and severe water deficit, respectively. Samples were collected at the flowering and maturity stages, and the dry matter, dry matter partitioning, yield, harvest index, pod harvest index, water use efficiency, and carbon‐13 isotope discrimination to estimate transpiration efficiency were determined. The study found that productivity (i.e., grain yield) was not lowered as a trade‐off of adaptability to water deficit irrigation. The genotypes either did not respond to deficit irrigation (KPS2 and AVMU 1635) in terms of grain yield or exhibited increased remobilisation of assimilates, either from pod walls to seeds (NM11) or from vegetative plant parts to pods/seeds (AVMU 1604), thereby increasing yields by 38% and 52%, respectively, under water deficit. However, the genotype KPS2 demonstrated stable yields and the greatest harvest index/pod harvest index (36%/69%) across all RDI treatments, suggesting superior adaptability to fluctuating water availability and efficient resource allocation, providing a suitable choice for a range of environmental conditions.
Rainforest fragmentation decreases the robustness of plant‐frugivore interaction networks
(2025) Becker, David; Li, Wande; Gurung, Ashtha; Rodriguez Martinez, Eduardo; Rojas, Emmanuel; Rodríguez‐Herrera, Bernal; Vollstädt, Maximilian G. R.; Grass, Ingo; Hiller, Thomas; Becker, David; Ecology of Tropical Agricultural Systems, University of Hohenheim, Stuttgart, Germany; Li, Wande; Ecology of Tropical Agricultural Systems, University of Hohenheim, Stuttgart, Germany; Gurung, Ashtha; Ecology of Tropical Agricultural Systems, University of Hohenheim, Stuttgart, Germany; Rodriguez Martinez, Eduardo; Ecology of Tropical Agricultural Systems, University of Hohenheim, Stuttgart, Germany; Rojas, Emmanuel; Reserva Biológica Tirimbina, Heredia, Costa Rica; Rodríguez‐Herrera, Bernal; Escuela de Biología y Centro de Investigación en Biodiversidad y Ecología Tropical (CIBET), Universidad de Costa Rica, San José, Costa Rica; Vollstädt, Maximilian G. R.; Instituto Mediterráneo de Estudios Avanzados (CSIC‐UIB), Mallorca, Balearic Islands, Spain; Grass, Ingo; Ecology of Tropical Agricultural Systems, University of Hohenheim, Stuttgart, Germany; Hiller, Thomas; Ecology of Tropical Agricultural Systems, University of Hohenheim, Stuttgart, Germany
Tropical rainforests are biodiversity hotspots that provide a variety of ecosystem functions and services. Seed dispersal by fruit‐eating birds is an important ecosystem process in the regeneration of tropical rainforests, which is increasingly threatened by widespread deforestation. In particular, the expansion of agricultural land often leads to forest fragmentation, which can have a negative impact on the interactions between plants and frugivores and thus on seed dispersal. However, little is known about how forest fragmentation affects the structure and robustness of plant–frugivore interaction networks. Here, we examined the effects of forest fragmentation on species richness of frugivorous birds interacting with focal tree species, and the structure and robustness of plant–frugivore interaction networks in the tropical lowland forests of northern Costa Rica. Species richness of frugivorous birds at the forest edges increased with fragment size and forest cover in the surrounding landscape as well as with local fruit availability. Modularity and robustness of plant–frugivore networks increased with enhanced fragment size and forest cover, while network specialization (H2′) increased only with greater forest cover. Additionally, the three common tanager species ( Ramphocelus passerinii , Thraupis palmarum , and Thraupis episcopus ) were identified as key bird species for network functioning by promoting among‐module and within‐module connectivity. Conservation measures should therefore not only focus on threatened specialist species, but more on the key species that enhance network structure and consequently increase the robustness of these trophic interaction networks. Ultimately, our study demonstrates that tropical forest fragmentation simplifies network structure, making these interactions more vulnerable to anthropogenic disturbances.
Use of seasonal forecasts in smallholder agricultural decision-making in the Central Rift Valley of Ethiopia
(2025) Kayamo, Samuel Elias; Berger, Thomas
Smallholder farmers in Ethiopia’s Central Rift Valley face pronounced risks from climate variability and erratic rainfall, challenges that threaten agricultural productivity, food security, and rural livelihoods. Rising climate hazards have spurred the promotion of seasonal precipitation forecasts as a promising means of supporting adaptation, yet the translation of such information into tangible adaptive action depends on a complex interplay of local agro-ecological conditions, available adaptation strategies, and behavioral responses. This thesis provides a comprehensive, interdisciplinary investigation into the economic value, adoption dynamics, and policy implications of seasonal forecast information for smallholder farmers, integrating agent-based modelling, dynamic risk assessment, crop-growth simulation, and framed field experiments. A principal focus of the research is the evaluation of adaptive management strategies for smallholder farmers enabled by seasonal forecasts. Examined strategies include crop and cultivar selection in response to rainfall outlooks, optimized planting dates, forecast-driven fertilizer management, and flexible in-season adjustments (such as crop switching or tied ridging). Each option is rigorously evaluated using observational, experimental and simulated data. In assessing the practical impacts of integrating seasonal rainfall forecast information into smallholder agricultural decision making, the results of this thesis indicate that forecast-based cultivar selection has the potential to support more effective management strategies for farmers in Ethiopia’s Central Rift Valley. By enabling better alignment of cultivar choices with anticipated seasonal rainfall conditions, farmers can enhance the adaptive capacity of their management practices in the face of climate variability. While the observed financial gains under realistic forecast accuracy are modest, these findings highlight that forecast-based cultivar selection can serve as a valuable decision-support tool. However, realizing the full potential of this approach depends not only on improvements in forecast skill, but also on the availability of reliable evidence regarding cultivar performance under diverse weather conditions and on substantial changes to seed breeding and distribution systems. Only when forecast-matching cultivars are made available to farmers promptly can the benefits of high-accuracy seasonal rainfall forecasts be more fully achieved. In the subsequent analysis, this thesis applies a state-contingent embedded risk framework to systematically explore how the timing of smallholder management decisions—specifically crop choice, sowing date, tied-ridging, relay cropping, and fertilization—can be optimized in light of seasonal rainfall forecast information. Using multi-stage discrete stochastic programming, the study evaluates adaptive strategies at the whole-farm level by simulating crop yield responses to management choices across 2,400 possible weather trajectories. The results show that forecast-informed management decisions can improve farmer income, but the extent and consistency of these benefits vary across seasons. The findings further reveal that opportunities for in-season adjustment—rather than choices made solely at the start of the season—are especially critical for achieving positive results in response to forecast information. By evaluating the long-term impacts of forecast-based decision making at the whole-farm level in the Central Rift Valley, this study emphasizes the need for more tailored and effective communication and advisory services of seasonal rainfall forecasts. In addition, the analysis highlights the inherent unpredictability of agricultural outcomes under climate uncertainty and demonstrates the continuing importance of building empirical understanding of how management actions and varying weather conditions together shape farm performance. These insights suggest that policy interventions aimed at strengthening real-time advisory systems and supporting farmers’ capacity for flexible, adaptive management are essential for fully realizing the benefits of seasonal rainfall forecasting in smallholder agriculture. The third component of the thesis explores how smallholder farmers receive, interpret, and act upon seasonal precipitation forecasts, drawing on evidence from framed field experiments conducted in Ethiopia’s Central Rift Valley. The analysis demonstrates that neither improvements in forecast accuracy nor dissemination of information alone are sufficient to induce significant behavioral change among farmers. Adoption is most likely when seasonal precipitation forecasts are communicated repeatedly, presented in clear and actionable formats, and tailored to local realities through trusted channels. The results further indicate that factors such as farmers’ education levels, prior experience with seasonal forecasts, and regular engagement with extension services play a central role in facilitating effective use of such information. The findings highlight the potential of digital innovations, such as smartphone-based advisories and AI-supported tools, to improve the reach and personalization of seasonal precipitation forecasts, provided these solutions are developed through participatory and user-centered approaches. Overall, the study underscores the importance of aligning advisory services with both the informational and contextual needs of smallholder farmers in order to foster more effective and inclusive adaptation to climate variability. Overall, the results of this thesis emphasize that the benefits of seasonal rainfall forecasts can only be fully realized through an integrated approach. This requires the combination of advances in forecast technology, adaptive input systems, effective communication, and supportive policy environments. Comprehensive and locally tailored adaptation packages—linking seasonal rainfall forecast information to improved access to seed and inputs, credit, training, and extension services—emerge as the most effective strategy for strengthening resilience. Ultimately, by connecting quantitative modeling, empirical experimentation, and policy analysis, this thesis provides a robust foundation for scaling up inclusive, impactful advisory systems based on seasonal rainfall forecasts to better equip smallholder farmers for managing risks associated with increasing rainfall variability.

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