Agricultural landscapes are increasingly being managed with the aim of enhancing the provisioning of multiple ecosystem services and sustainability of production systems. However, agricultural ...management that maximizes provisioning ecosystem services can often reduce both regulating and maintenance services. We hypothesized that agroforestry reduces trade-offs between provisioning and regulating/maintenance services. We conducted a quantitative synthesis of studies carried out in sub-Saharan Africa focusing on crop yield (as an indicator of provisioning services), soil fertility, erosion control, and water regulation (as indicators of regulating/maintenance services). A total of 1106 observations were extracted from 126 peer-reviewed publications that fulfilled the selection criteria for meta-analysis of studies comparing agroforestry and non-agroforestry practices (hereafter control) in sub-Saharan Africa. Across ecological conditions, agroforestry significantly increased crop yield, total soil nitrogen, soil organic carbon, and available phosphorus compared to the control. Agroforestry practices also reduced runoff and soil loss and improved infiltration rates and soil moisture content. No significant differences were detected between the different ecological conditions, management regimes, and types of woody perennials for any of the ecosystem services. Main trade-offs included low available phosphorus and low soil moisture against higher crop yield. This is the first meta-analysis that shows that, on average, agroforestry systems in sub-Saharan Africa increase crop yield while maintaining delivery of regulating/maintenance ecosystem services. We also demonstrate how woody perennials have been managed in agricultural landscapes to provide multiple ecosystem services without sacrificing crop productivity. This is important in rural livelihoods where the range of ecosystem services conveys benefits in terms of food security and resilience to environmental shocks.
Africa’s need to double food production and feed the burgeoning human population, without compromising its natural resource base, has raised the momentum for sustainable agricultural intensification ...on the continent. Many studies describe agronomic practices that can increase productivity on existing agricultural land without damaging the environment and without increasing the agricultural carbon footprint. However, there is limited information on specific practices with the greatest potential to contribute to sustainable intensification on smallholder farms in sub-Saharan Africa, while simultaneously keeping the carbon footprint low. The objectives of this review were to (1) identify good agronomic practices with potential for contributing to sustainable intensification across sub-Saharan Africa, (2) synthesize available information on benefits and synergies from these technologies, and (3) discuss bottlenecks in their adoption in order to obtain insights that inform the formulation of supportive policies. Agroforestry, cereal-legume intercropping, conservation agriculture, doubled-up legume cropping, fertilizer micro-dosing, planting basins, and push-pull technology were identified as key agronomic innovations widely promoted in sub-Saharan Africa. We show that these innovations can build synergies and increase resource use efficiency while reducing agricultural carbon footprint. We outline the benefits, trade-offs, and limitations of these practices and discuss their potential role in strengthening food sovereignty and climate change adaptation and mitigation.
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•Low soil fertility and profitability affect the sustainability of households differently.•Households typology with sustainability assessment help identify relevant recommendations.•A ...poverty trap is identified along with strategies to step-up in terms of livelihood.•Sustainable intensification options are recommended with intercropping and livestock.
In low-income countries, the livelihoods of smallholders are affected to different extent by multiple issues, such as food insecurity or low soil fertility, depending on their multiple assets and farming characteristics. In this study, we aim at assessing the current sustainability of households in Tanzania to suggest potential changes in farming system to increase the household́ sustainability. Household survey data from 891 households in two regions of Tanzania (dry Dodoma and humid Morogoro) were used to build composite sustainability indices representing the three pillars of sustainability (economic, environmental and social), based on 46 basic indicators. Then, a household typology was developed through principal component analysis and hierarchical clustering analysis of descriptive variables, and regression analysis linked the sustainability of farms with household characteristics. The analysis revealed significant differences in household types that relied on different livelihood strategies including particularly a “Gathering-based” type in Dodoma and two “Crop-based” types in both regions. These livelihoods significantly influenced the level of farming system sustainability. Particularly, the households in the “Gathering-based” type performed worst on all three pillars of sustainability. By examining the level of capitals from the different household types, we identified that the “Gathering-based” type and “Crop-based” types could improve their livelihood and be better off if they adopt various upgrading solutions. Such solutions include intercropping and optimised weeding to increase productivity and resource-use efficiency, for which these households have sufficient labour resources. Additionally, livestock rearing and use of fertilisers coupled with rainwater harvesting can increase soil fertility and water use efficiency, and hence food security, without compromising the environmental component of sustainability. To facilitate the adoption of these sustainable intensification options, agricultural policies and appropriate training need to be implemented to fit the local context and diversity of household types.
Increasing frequency, intensity and duration of severe weather events are posing major challenges to global food security and livelihoods of rural people. Agriculture has evolved through adaptation ...to local circumstances for thousands of years. Local experience in responding to severe weather conditions, accumulated over generations and centuries, is valuable for developing adaptation options to current climate change. This study aimed to: (i) identify tree species that reduce vulnerability of cropping systems under climate variability; and (ii) develop a method for rapidly assessing vulnerability and exploring strategies of smallholder farmers in rural areas exposed to climate variability. Participatory Rural Appraisal methods in combination with Geographical Information Systems tools and statistical analysis of meteorological data were used to evaluate local vulnerability to climate change and to investigate local adaptation measures in two selected villages in Vietnam, one of the countries most vulnerable to climate change. The low predictability of severe weather events makes food crops, especially grain production, insecure. This study shows that while rice and rain-fed crops suffered over 40 % yield losses in years of extreme drought or flood, tree-based systems and cattle were less affected. 13 tree species performed well under the harsh local climate conditions in home and forest gardens to provide income, food, feed and other environmental benefits. Thus, this research suggests that maintenance and enhancement of locally evolved agroforestry systems, with high resilience and multiple benefits, can contribute to climate change adaptation.
Agricultural production systems are affected by complex interactions between social and ecological factors, which are often hard to integrate in a common analytical framework. We evaluated ...differences in crop production among farms by integrating components of several related research disciplines in a single socio-ecological analysis. Specifically, we evaluated spring barley (Hordeum vulgare, L.) performance on 34 farms (organic and conventional) in two agro-ecological zones to unravel the importance of ecological, crop and management factors in the performance of a standard crop. We used Projections to Latent Structures (PLS), a simple but robust analytical tool widely utilized in research disciplines dealing with complex systems (e.g. social sciences and chemometrics), but infrequently in agricultural sciences. We show that barley performance on organic farms was affected by previous management, landscape structure, and soil quality, in contrast to conventional farms where external inputs were the main factors affecting biomass and grain yield. This indicates that more complex management strategies are required in organic than in conventional farming systems. We conclude that the PLS method combining socio-ecological and biophysical factors provides improved understanding of the various interacting factors determining crop performance and can help identify where improvements in the agricultural system are most likely to be effective.
Assessing effects of climate change on agricultural systems and the potential for ecological intensification to increase food security in developing countries is essential to guide management, ...policy-making and future research. ‘Push-pull’ technology (PPT) is a poly-cropping design developed in eastern Africa that utilizes plant chemicals to mediate plant–insect interactions. PPT application yields significant increases in crop productivity, by reducing pest load and damage caused by arthropods and parasitic weeds, while also bolstering soil fertility. As climate change effects may be species- and/or context-specific, there is need to elucidate how, in interaction with biotic factors, projected climate conditions are likely to influence future functioning of PPT. Here, we first reviewed how changes in temperature, precipitation and atmospheric CO2 concentration can influence PPT components (i.e., land use, soils, crops, weeds, diseases, pests and their natural enemies) across sub-Saharan Africa (SSA). We then imposed these anticipated responses on a landscape-scale qualitative mathematical model of maize production under PPT in eastern Africa, to predict cumulative, structure-mediated impacts of climate change on maize yield. Our review suggests variable impacts of climate change on PPT components in SSA by the end of the 21st century, including reduced soil fertility, increased weed and arthropod pest pressure and increased prevalence of crop diseases, but also increased biological control by pests’ natural enemies. Extrapolating empirical evidence of climate effects to predict responses to projected climate conditions is mainly limited by a lack of mechanistic understanding regarding single and interactive effects of climate variables on PPT components. Model predictions of maize yield responses to anticipated impacts of climate change in eastern Africa suggest predominantly negative future trends. Nevertheless, maize yields can be sustained or increased by favourable changes in system components with less certain future behaviour, including higher PPT adoption, preservation of field edge density and agricultural diversification beyond cereal crops.
•Push-pull technology (PPT) improves cereal yield based on agroecological principles•We review future climate change impacts on PPT components across sub-Saharan Africa•Anticipated PPT component responses are imposed on a holistic model of maize yield•Predictions are negative, but reversible through PPT & agricultural diversification
Rainfall variability is becoming more profound in East Africa. Smallholders relying on rainfed agriculture are particularly affected and need to adapt their farming systems accordingly. This study ...examined the measures small-scale farmers use to adapt to, or cope with rainfall variability and their rated perceived effectiveness. It also explored limitations to adoption of measures and sources of learning measures. Questionnaire-based interviews were held with 80 smallholder farmers, both female and male, living in Kisumu and Trans Nzoia counties in Kenya who had regular or sporadic access to advisory services (denoted trained and non-trained farmers). Trained farmers used more adaptation measures, especially of the measures perceived to be more effective, than non-trained farmers. Female farmers felt more limited by lack of knowledge than male farmers, while money, land and labour limited the smallholder farmers equally. Few measures were used to overcome limitations, but several limitations were covered within the advisory package used for trained farmers, and therefore large differences were seen not only in numbers of measures used, but also in the choice of measures and perceived effectiveness of use. Thus advisory services and policy interventions can play important roles in future efforts to improve adoption of measures.
The study of yield gaps has become more complex, prompting the use of varied approaches to measure yields and a wider range of factors to explain these gaps. In the Global North, the focus is on ...precision farming, whereas in sub-Saharan Africa (SSA), a broader perspective is necessary due to pronounced variability in farmland conditions. While biogeophysical and management factors have been traditional focal points in yield gap analyses, socio-economic and institutional factors are increasingly recognized as significant, especially in SSA. This review synthesizes research from the past decade in SSA that integrates biogeophysical, management, farm characteristics, and institutional factors in yield gap discussions. The findings indicate a slow shift in including socio-economic factors, with management, particularly nutrient supply and crop management, remaining predominant. However, there is a growing trend towards methodological diversity, such as the adoption of remote sensing and GIS in recent years. Case studies from Kenya and Ghana, utilizing field surveys, interviews, panel data, and spatial analysis, highlight how a multifaceted approach can enhance our understanding of the various elements influencing maize yield gaps in SSA.
•Agroforestry describes a set of technologies, a landscape approach and a drive to greater policy synergy.•Synergy can evolve from coexistence and agreed boundaries towards joint programs and ...innovation.•The FEW (food, energy, water) agenda needs to include rural income as proximate driver of change.•The LER (land equivalence ratio) concept can be expanded to analyse landscape multifunctionality.•Coherent agro + forestry policies are relevant for rural-urban transitions and landscape transformations.
Among the Sustainable Development Goals (SDGs) three broad groups coexist: first, articulating demand for further human resource appropriation, second, sustaining the resource base, and third, redistributing power and benefits. Agriculture and forestry jointly interact with all three. The SDG portfolio calls for integrated land use management. Technological alternatives shift the value of various types of land use (forests, trees and agricultural practices) as source of ‘ecosystem services’. At the interface of agriculture and forestry the 40-year old term agroforestry has described technologies (AF1) and an approach to multifunctional landscape management (AF2). A broadened Land Equivalence Ratio (LER) as performance metric indicates efficiency. Agroforestry also is an opportunity to transcend barriers between agriculture and forestry as separate policy domains (AF3). Synergy between policy domains can progress from recognized tradeoffs and accepted coexistence, via common implementation frames, to space for shared innovation. Further institutional space for integral ‘all-land-uses’ approaches is needed.
Organic agriculture and organic food have expanded in recent decades but have undergone conventionalisation. Some claim that this contradicts some or all of the principles of ‘health’, ‘ecology’, ...‘fairness’ and ‘care’ established by the International Federation of Organic Agricultural Movement (IFOAM). It is currently unclear how research on organic food/agriculture is structured, whether it embraces these principles, or how key crop diversification, driving sustainability, are addressed. To fill these knowledge gaps, we conducted a bibliometric analysis of 10,030 peer-reviewed articles published from 1945 to 2021 with topic and textual analysis. Our main findings were the following: (1) research is compartmentalised into scales and disciplines, with at field-scale ‘weed’, ‘soil’, ‘pest and disease’ management and ‘livestock farming’ seldom addressed together, or with environmental assessment separated from socioeconomic studies at farm scale. (2) The proportion of publications on ‘consumers’ preferences’ and ‘product quality’ research almost tripled in 20 years, from 10 to 27%, emphasizing the consumer orientation of research on organic agriculture and organic food. (3) Only 4% of articles covered all four IFOAM principles, while associated values such as ‘resilience’, ‘integrity’, ‘equity’, ‘transparency’ and ‘justice’ were even less frequently addressed. (4) Fewer diversification practices have been tested in organic than in conventional agriculture research, with fewer articles on ‘crop mixtures’ or ‘bee-friendly crops’ and a smaller range of legumes considered. (5) Research on genetic improvement and processing of organic legumes is lacking, which could constrain adoption of legumes in organic farming even more than in conventional agriculture. These results indicate a need for increasing interdisciplinary efforts at field level, with systematic measurement of multiple processes (weed-nutrient-pest dynamics). Future studies on organic agriculture should combine several diversification practices and legumes, with relevant indicators addressing the IFOAM values explicitly, and consider the whole value chain by linking producers with consumers.
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