• Energy Research

Drought and heat-tolerant crops, such as Pearl millet (Pennisetum glaucum), are priority crops for fighting hunger in semi-arid regions. Assessing its performance under future climate scenarios is critical for determining its resilience and sustainability. Field experiments were conducted over two consecutive seasons (2015/2016 and 2016/2017) to determine the yield responses of the crop (pearl millet variety “Okoa”) to microdose fertilizer application in a semi-arid region of Tanzania. Data from the experiment were used to calibrate and validate the DSSAT model (CERES Millet). Subsequently, the model evaluated synthetic climate change scenarios for temperature increments and precipitation changes based on historic observations (2010–2018). Temperature increases of +0.5 to +3.0 °C (from baseline), under non-fertilized (NF) and fertilizer microdose (MD) conditions were used to evaluate nine planting dates of pearl millet from early (5 December) to late planting (25 February), based on increments of 10 days. The planting date with the highest yields was subjected to 49 synthetic scenarios of climate change for temperature increments and precipitation changes (of −30% up to +30% from baseline) to simulate yield responses. Results show that the model reproduced the phenology and yield, indicating a very good performance. Model simulations indicate that temperature increases negatively affected yields for all planting dates under NF and MD. Early and late planting windows were more negatively affected than the normal planting window, implying that temperature increases reduced the length of effective planting window for achieving high yields in both NF and MD. Farmers must adjust their planting timing, while the timely availability of seeds and fertilizer is critical. Precipitation increases had a positive effect on yields under all tested temperature increments, but Okoa cultivar only has steady yield increases up to a maximum of 1.5 °C, beyond which yields decline. This informs the need for further breeding or testing of other cultivars that are more heat tolerant. However, under MD, the temperature increments and precipitation change scenarios are higher than under NF, indicating a high potential of yield improvement under MD, especially with precipitation increases. Further investigation should focus on other cropping strategies such as the use of in-field rainwater harvesting and heat-tolerant cultivars to mitigate the effects of temperature increase and change in precipitation on pearl millet yield.

The study of psychological barriers and the attribution of social meaning is a complex and subjective process, but essential for the development of strategies to adapt to climate change and land-use management. The objective of this paper is to point out and discuss aspects that comprise climate vulnerability, especially regarding the climate perceptions understood as an element for the development of community adaptation strategies. The first part presents two study cases and the second part presents propositions for developing climate adaptation strategies based on the results of these cases. The paper focuses on two aspects: the perception of climate dynamics and the relationship between vulnerability and local climate dynamics. In order to establish the relationship between climate dynamics and the level of vulnerability perceived, a qualitative approach was adopted. Field data collection consisted of observing local civil association meetings and conducting semi-structured interviews with local actors. Although both communities studied are strongly affected by climate events, their perception of climate influences is essentially different. The difference in perception arises mainly from the different context in which climate events acquire meaning, rather than any ability of assigning meaning to possible climate change. To understand the dynamics of establishing an adaptation strategy, the motivational problems would be a stimulus, a causative agent of reflections on the conditions of vulnerability to climate change and reflection about their limit-situations. The final propositions present “Adaptation learning process pre-steps framework” that emerges from the description of contrasts in perceptions/cognitions observed between the two study cases. It is a model for the visualization of different and better living conditions, the unknown-viable, which enable social actors to become aware of capacity of acting and governance.

Given the persistent poor livelihood of cocoa-farming households, future climate predictions and the worldwide demand pressure for higher cocoa quality and productivity, there is still a strong need to find new approaches that guarantee a sustainable cocoa future in cocoa-producing countries amongst which Cameroon is one of them. This exploratory research investigates potential future pathways for the cocoa sector in Cameroon by mapping the perceptions of actors involved in the socio-technical regime. Qualitative expert interviews, structured questionnaires and field observation, as well as a focus group discussion have been applied to understand how a sustainability transition can be triggered. The study shows that actors envisage a sustainability change which determines their actions; however, their perceptions towards future transitions are not actively coordinated. Actors are not finding a way of adopting new organizational structures and letting a transition occur effectively, like in the case of certification standards. An alignment of perceptions and activities, and a stronger cooperation between the private and public are strongly recommended. The study encourages to consider a coordination of actors’ perceptions towards future scenarios as a starting point to study sustainability transitions.

ABSTRACTLand degradation continues to be a major concern for agriculture in developing countries, including Tanzania. Agroforestry is one solution that benefits food production and reduces land degradation. However, various challenges hinder its widespread adoption. This study uses an integrated assessment framework, combining MESMIS (an indicator-based sustainability assessment framework) and ScalA (a scaling-up assessment tool), to evaluate sustainability and constraints to the widespread implementation of agroforestry in semi-arid Tanzania. The main goals are to: 1) identify existing agroforestry technologies adopted by smallholder farmers; 2) evaluate farmers’ perception of sustainability regarding each technology's environmental, economic, and social impact; and 3) identify constraints related to the widespread adoption. Results show that farmers consider the following four technologies as the most sustainable: (i) tied ridge + tree intercropping; (ii) contour planting + tree intercropping; (iii) Chololo pits + tree intercropping; and (iv) tree intercropping alone. The findings indicate that, although farmers perceive the technologies positively, adoption is also influenced by local climate, socio-economic status, and institutional factors. The study highlights that a positive perception alone cannot ensure widespread adoption, emphasizing the importance of considering contextual factors. Further testing and application of the proposed framework in similar and comparative settings is encouraged as it provides valuable guidance when evaluating different agroecosystems holistically.

AbstractDiverse, severe, and location-specific impacts on agricultural production are anticipated with climate change. The last IPCC report indicates that the rise of CO2 and associated “greenhouse” gases could lead to a 1.4 to 5.8 °C increase in global surface temperatures, with subsequent consequences on precipitation frequency and amounts. Temperature and water availability remain key factors in determining crop growth and productivity; predicted changes in these factors will lead to reduced crop yields. Climate-induced changes in insect pest, pathogen and weed population dynamics and invasiveness could compound such effects. Undoubtedly, climate- and weather-induced instability will affect levels of and access to food supply, altering social and economic stability and regional competiveness. Adaptation is considered a key factor that will shape the future severity of climate change impacts on food production. Changes that will not radically modify the monoculture nature of dominant agroecosystems may moderate negative impacts temporarily. The biggest and most durable benefits will likely result from more radical agroecological measures that will strengthen the resilience of farmers and rural communities, such as diversification of agroecosytems in the form of polycultures, agroforestry systems, and crop-livestock mixed systems accompanied by organic soil management, water conservation and harvesting, and general enhancement of agrobiodiversity. Traditional farming systems are repositories of a wealth of principles and measures that can help modern agricultural systems become more resilient to climatic extremes. Many of these agroecological strategies that reduce vulnerabilities to climate variability include crop diversification, maintaining local genetic diversity, animal integration, soil organic management, water conservation and harvesting, etc. Understanding the agroecological features that underlie the resilience of traditional agroecosystems is an urgent matter, as they can serve as the foundation for the design of adapted agricultural systems. Observations of agricultural performance after extreme climatic events (hurricanes and droughts) in the last two decades have revealed that resiliency to climate disasters is closely linked to farms with increased levels of biodiversity. Field surveys and results reported in the literature suggest that agroecosystems are more resilient when inserted in a complex landscape matrix, featuring adapted local germplasm deployed in diversified cropping systems managed with organic matter rich soils and water conservation-harvesting techniques. The identification of systems that have withstood climatic events recently or in the past and understanding the agroecological features of such systems that allowed them to resist and/or recover from extreme events is of increased urgency, as the derived resiliency principles and practices that underlie successful farms can be disseminated to thousands of farmers via Campesino a Campesino networks to scale up agroecological practices that enhance the resiliency of agroecosystems. The effective diffusion of agroecological technologies will largely determine how well and how fast farmers adapt to climate change.

The low agricultural productivity of key crops and food insecurity continue to be key issues in Sub-Saharan Africa (SSA) and Tanzania. The growing population, depleting resources, and changing climate further amplify these issues. Globally, many agricultural technologies (AgTs) are available as pathways for improved agricultural productivity and food security, however, they have had relatively little success in SSA and Tanzania. This is because the uptake of AgTs is a complex process, which is highly localized, involving multiple actors, stages, and spatial and time dimensions. Smallholder farmers often experience issues of sustainability, constraints for adoption, and scaling-up throughout the uptake process of AgTs, all of which vary by region. This indicates a need for a systematic and simultaneous understanding of sustainability, constraints for adoption, and scaling-up of AgTs to better guide agricultural strategy and policy interventions in SSA and Tanzania. Moreover, in order to understand the local settings better, a consideration of the perceptions of the farmers themselves, who are the primary actors in the uptake process of AgTs, is key. Acknowledging this, the study takes on a case study approach, using the scaling-up assessment (ScalA) method and three focus group discussions with a total of 44 smallholder farmers to systematically and simultaneously assess the sustainability, constraints for adoption, and scaling-up of three AgTs (use of fertilizers, improved seeds, and small-scale irrigation) in Tanzania. The study finds that the farmers perceive all three AgTs to be sustainable for the study region. Adoption rates are perceived to be medium for use of fertilizers, high for improved seeds, and low for small-scale irrigation. The most significant constraints for adoption experienced by the farmers are lack of technical physical inputs, marketing facilities, and know-how. Scaling-up is perceived to be well fulfilled for use of fertilizers and improved seeds, but only partially fulfilled for small-scale irrigation, which is the most limited of the three AgTs. The most significant constraints for scaling-up experienced by farmers are a lack of confidence in the added value of the AgTs beyond project activities, marketing facilities, and technical physical inputs. The overall success potential is high for the use of fertilizers and improved seeds, and the average for small-scale irrigation. The farmers’ perceptions partially indicate why the bundle of AgTs is lacking in the study region and provide a basis for discussing targeted agricultural and policy interventions in Tanzania.

AbstractMaize is one of the world’s most important cereals, cultivated in a wide range of environments. Besides the importance of maize and the gains in yield from selection schemes, commercial breeding drastically reduced the number of cultivars of this crop. Current common sense states that hybrids, when compared to open-pollinated cultivars, are a better adaptation strategy to cope with the impacts of climate change. However, the performance and resilience of cultivars with different levels of improvement are still not explored in this context. Four cultivars—a commercial hybrid, one commercially improved open-pollinated, one improved open-pollinated derived from participatory breeding, and one from a farmer’s selection—were tested using the CERES-Maize crop model. Field experiments conducted in Brazil were used for calibration and evaluation. Synthetic scenarios of climate change resulted from the application of the incremental method on historical series of observations (30 years), with temperature increments ranging from +0.5 up to +3.0 °C and precipitation changes from −30 up to +30%. Planting dates consisted in nine dates (August 1–December 1, each 15 days). Results demonstrate that the model could mimic the phenology and yield of two improved open-pollinated cultivars (MPA01 and Fortuna) and the hybrid (AS1548). One open-pollinated cultivar could not be validated due to its high phenotypic variability. Yield response surfaces showed distinct impacts among cultivars, with improved open-pollinated cultivar MPA01 having a higher yield stability when compared to the hybrid. Early planting dates produced lower yields with higher risk of crop failure for all cultivars. Late planting dates produced higher yields with higher failure risk. Considering risk and yield, the best planting window for all cultivars and scenarios is between September and October. Our results demonstrate, for the first time, that improved open-pollinated cultivars are equivalent or more resilient than hybrids to yield changes under different scenarios of abiotic stresses.