Types of Research
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In many countries in Sub-Saharan Africa and South Asia smallholder farmers are among the most vulnerable to climatic changes, and the observed shocks and stresses associated with these changes impact agricultural systems in many ways. This research brief offers findings on observed or measured changes in precipitation, temperature or both, on five biophysical pathways and systems including variable or changing growing seasons, extreme events, biotic stressors, plant species density, richness and range, impacts to streamflow, and impacts on crop yield. These findings are the result of a review of relevant documents cited in Kilroy (2015), references included in the IPCC draft Special Report on Food Security, and targeted searches from 2015 - present for South Asia and Sub-Saharan Africa.
Much literature discusses the importance of investing in human capital—or “the sum of a population’s health, skills, knowledge, experience, and habits” (World Bank, 2018, p. 42)—to a country’s economic growth. For example, the World Bank reports a “chronic underinvestment” in health and education in Nigeria, noting that investing in human capital has the potential to significantly contribute to economic growth, poverty reduction, and societal well-being (World Bank, 2018). This research brief reports on the evidence linking investment in human capital—specifically, health and education—with changes in economic growth. It reviews the literature for five topic areas: Education, Infectious Diseases, Nutrition, Primary Health Care, and Child and Maternal Health. This review gives priority focus to the countries of Bangladesh, Burkina Faso, Democratic Republic of Congo, Ethiopia, India, Kenya, Madagascar, Nigeria, Rwanda, and Tanzania. For each topic area, we report the evidence in support of a pathway from investing in human capital to economic growth.
After cereals, root and tuber crops - including sweetpotato and yam (in addition to cassava and aroids), are the second most cultivated crops in tropical countries. This literature review examines the environmental constraints to, and impacts of, sweetpotato and yam production systems in Sub-Saharan Africa (SSA) and South Asia (SA). The review highlights crop-environment interactions at three stages of the sweetpotato/yam value chain: pre-production (e.g., land clearing), production (e.g., soil, water, and input use), and post-production (e.g., waste disposal, crop storage and transport). We find that sweetpotato and yam face similar environmental stressors. In particular, because sweetpotato and yam are vegetatively propagated, the most significant (and avoidable) environmental constraints to crop yields include disease and pest infection transmitted through the use of contaminated planting materials. Published estimates suggest yield gains in the range of 30–60% can be obtained through using healthy planting material. Moreover, reducing pest damage in the field can greatly increase the storage life of root and tuber crops after harvest – currently losses from rot and desiccation can claim up to 100% of stored sweetpotato and yam on smallholder farms.
In this brief we examine the environmental constraints to, and impacts of, smallholder sorghum and millet production systems in Sub-Saharan Africa (SSA) and South Asia (SA). Millet in this paper primarily refers to pearl millet (Pennisetum glaucum), although a number of other millets of significance to smallholder production and food security are also discussed. Sorghum and millets are known for being more tolerant of major environmental stresses including drought and poor soil quality than other major cereals. But water availability is still among the greatest constraints to increased grain production, and soil fertility also significantly limits yields, especially in cases where cultivation occurs on marginal lands and where crop residues are removed for alternative uses. Ultimately sorghum and millets’ relatively higher tolerance to abiotic stresses is expected to promote an increase in global cropping area for sorghum and millets as an adaptation to climate change. Sorghum and millet exhibit relatively few of the environmental impacts commonly associated with more intensively cultivated crops such as fertilizer runoff, pesticide contamination, or water depletion, since both of these crops are overwhelmingly grown by smallholder farmers with few, if any, chemical or irrigation inputs. Nevertheless, the tendency to grow sorghum and millet on marginal and heavily sloped lands does pose some environmental risks – including soil degradation and erosion – that can be mitigated through the adoption of best practices as described in the brief.
Maize has expanded through the 20th and into the 21st century to become the principle staple food crop produced and consumed by smallholder farm households in Sub-Saharan Africa (SSA), and maize production has also expanded in South Asia (SA) farming systems. In this brief we examine the environmental constraints to, and impacts of, smallholder maize production systems in SSA and SA, noting where findings apply to only one of these regions. We highlight crop-environment interactions at three stages of the maize value chain: pre-production (e.g., land clearing), production (e.g., fertilizer, water, and other input use), and post-production (e.g., waste disposal and crop storage). At each stage we emphasize environmental constraints on maize production (such as poor soil quality, water scarcity, or crop pests) and also environmental impacts of maize production (such as soil erosion, water depletion, or chemical contamination). We then highlight best or good practices for overcoming environmental constraints and minimizing environmental impacts in smallholder maize production systems. Evidence on environmental constraints and impacts in smallholder maize production is uneven. Many environmental concerns such as biodiversity loss are commonly demonstrated more broadly for the agroecology or farming systems in which maize is grown, rather than specifically for the maize crop. And more research is available on the environmental impacts of agrochemical-based intensive cereal farming in Asia (where high-input maize is a common component) than on the low-input subsistence-scale maize cultivation more typical of SSA. Decisive constraint and impact estimates are further complicated by the fact that many crop-environment interactions in maize and other crops are a matter of both cause and effect (e.g., poor soils decrease maize yields, while repeated maize harvests degrade soils). Fully understanding maize-environment interactions thus requires recognizing instances where shortterm adaptations to environmental constraints might be exacerbating other medium- or long-term environmental problems. Conclusions on the strength of published findings on crop-environment interactions in maize systems further depend on one’s weighting of economic versus ecological perspectives, physical science versus social science, academic versus grey literature, and quantity versus quality of methods and findings.
Rice is the most important food crop of the developing world and is grown on over 155 million ha worldwide. Food security of the poor, especially in Asia, depends critically on rice availability at an affordable price. In this brief we examine the environmental constraints to, and impacts of, smallholder rice production systems in South Asia (SA) and Sub-Saharan Africa (SSA), noting where the analysis applies to only one of these regions. We highlight crop-environment interactions at three stages of the rice value chain: pre-production (e.g., land clearing), production (e.g., water and other input use), and post-production (e.g., waste disposal). At each stage we emphasize environmental constraints on production (e.g., poor soil quality, water scarcity, crop pests) and also environmental impacts of crop production (e.g., soil erosion, water depletion, pest resistance). We then highlight best or good practices for minimizing negative environmental impacts in smallholder rice production systems. Evidence on environmental issues in smallholder rice production is uneven. Far more research is available for Asian rice production systems, as compared to African rice systems. And with the possible exception of the evidence on water limits to increasing productivity, conclusions on the strength of published findings on crop-environment interactions in rice depends on one’s weighting of economic versus ecological perspectives, physical science versus social science, academic versus grey literature, and quantity versus quality of methods and findings.
This literature review examines the environmental constraints to, and impacts of, wheat production systems in South Asia (SA) and Sub-Saharan Africa (SSA). The review highlights crop-environment interactions at three stages of the wheat value chain: pre-production (e.g., land availability), production (e.g., heat, water, and soil), and post-production (e.g. storage, crop residues, and transport). At each stage we emphasize environmental constraints on production (e.g., poor soil quality, water scarcity, crop pests, etc.) and also environmental impacts of crop production (e.g., soil degradation, water depletion and pollution, greenhouse gas emissions, etc.). We then highlight published best practices for overcoming environmental constraints and minimizing environmental impacts in wheat production systems. We find that wheat is a significant crop that will need to increase production to meet increasing demand. Most land suitable for wheat production is already under cultivation. Improved production methods are needed to address the demand and avert environmental impacts of producing wheat. It should not be assumed that improved varieties alone will be able to realistically address growing demands for wheat. Improved variety seeds should be combined with best practices of improved crop management techniques: optimal planting time, zero tillage, fertilizer management, intercropping, crop residue incorporation, and improved storage techniques.
Consumer attitudes are a key component in private sector market segmentation. Knowledge about consumers’ tastes can lead to better product design and more effective communication with target markets. Similarly, evidence suggests that farmers’ attitudes influence whether they adopt productivity-increasing technologies. Using consumer insights from the private sector, agricultural intervention programs can use market research, product development, and communication strategies to better understand farmers as consumers and best target interventions. This brief provides an overview of how farmers' attitudes affect their willingness to adopt new technology, and how knowledge of farmer attitudes can improve program design and implementation.