Types of Research
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.
This report investigates the potential environmental and socio-economic benefits and costs of glyphosate resistant cassava. Glyphosate resistant crops (also referred to as glyphosate tolerant) have been rapidly adopted by a number of crop producers because they simplify and/or reduce the cost of weed management. Glyphosate resistant crops also provide external environmental benefits by promoting reduced tillage agriculture, decreasing erosion and increasing soil health. However, glyphosate resistant crops also have some environmental costs, potentially leading to increased use of herbicides and environmental contamination. Because transgenic glyphosate resistant cassava is not currently in use, literature on its potential environmental and socioeconomic costs and benefits is limited. Therefore, this report draws on the literature for glyphosate resistant crops that are in current use, including maize, soybeans, sugar beets and canola (rapeseed). We find that socioeconomic and environmental impacts of glyphosate resistant crops differ by crop-type, agroecological conditions, production systems and local regulatory structure. Therefore, some benefits and costs associated with other glyphosate resistant crops may not be applicable to glyphosate resistant cassava.
This literature review examines the environmental impacts of water buffalo in pastoral and mixed farming systems in Sub-Saharan Africa, South Asia, and South America). The environmental impacts of water buffalo are less widely studied than those of the other livestock species included in this series; typically, the environmental impacts of water buffalo are incorporated into discussions of cattle without more detailed impacts being broken down by bovine type. In Asia and India, where the majority of buffalo are raised, buffalo are typically kept in small herds of only a few animals, which may minimize the local impacts of their grazing on vegetation, soil erosion and water pollution. Some aspects of buffalo feeding and life cycle patterns, as observed in the Amazon, may cause their greenhouse gas emissions to differ from those of cattle: buffalo can fatten on a wider range of grasses, reach market size in a shorter time, transition better from dry to wet seasons, and are more resistant to bovine diseases. While buffalo grazing and trampling can lead to land degradation, buffalo can contribute to nutrient and resource cycling in farming systems because their manure is considered good fertilizer and they can remove and utilize biomass grown on agricultural plots. Mitigation strategies vary by category of environmental impact, but largely suggest improved productivity to reduce land conversion, modified management systems (e.g., biodiversity, water use and consumption, farm and pastures, and waste), and the reduction of livestock numbers altogether.
This literature review examines the environmental impacts of cattle in pastoral and mixed farming systems in Sub-Saharan Africa and South Asia. Cattle are frequently cited as having the most severe overall environmental impacts among livestock species due to: methane and nitrous oxide released from digestion and manure; land use and conversion; desertification; inefficient ratio of weight of feed and water consumed to weight of meat and dairy produced; conflicts between livestock herders and wildlife; the large volume of wastewater produced in meat and hide processing; and overgrazing of riparian areas. However, cattle have also been found to provide several environmental benefits such as keeping wildlife corridors open, preventing the spread of noxious weeds, and promoting the growth of local vegetative species. Mitigation strategies vary by category of environmental impact, but largely suggest improved productivity to reduce land conversion, modified management systems (e.g., biodiversity, water use and consumption, farm and pastures, grain and other feed, and waste), and the reduction of livestock numbers altogether.
This literature review examines the environmental impacts of goats in pastoral and mixed farming systems in Sub-Saharan Africa and South Asia. We find that the most notable environmental implications of goats stem from their ability to graze on a wide variety of biomass sources in frequently marginal environments; while this intensive grazing stimulates biodiversity loss and may be more severe than grazing by other livestock species, goats are not a major driver of forest clearing due to their low economic value. Environmental benefits of goat production include keeping wildlife corridors open, preventing the spread of noxious weeds, and promoting the growth of local vegetative species through moderate grazing. Goats are also more water-efficient than large ruminants such as cattle. Mitigation strategies vary by category of environmental impact, but largely suggest improved productivity to reduce land conversion, modified management systems (e.g., biodiversity, water use and consumption, grazing intensity and frequency, and waste), and the reduction of livestock numbers altogether.
This literature review examines the environmental impacts of chickens in pastoral and mixed farming systems in Sub-Saharan Africa and South Asia. Compared to ruminant species (cattle, water buffalo, and goats), chickens produce lower carbon dioxide, methane, and nitrous oxide emissions, are a less significant driver of human expansion into natural habitat or of overgrazing, have lower impacts on the water cycle, and cause less destruction of natural habitats. Poultry’s major impacts on land degradation result from the production of their grain-intensive feed. Chicken production also poses a threat to avian biodiversity, as chickens are susceptible to viruses and act as vectors of disease transmission to avian wildlife. Chicken manure is widely viewed as a valuable fertilizer in developing countries, although transportation costs limit manure sales in local markets and the high nitrogen-phosphorous ratio can impact certain soils and water. Mitigation strategies vary by category of environmental impact, but largely suggest modified management systems (e.g., biodiversity, health, livestock feed efficiency, and waste).
This report combines analyses from four previous EPAR briefs on the effects of climate change on maize, rice, wheat, sorghum, and millet production in Sub-Saharan Africa (SSA). In addition, this brief presents new analysis of the projected impact of climate changes in SSA. We include comparisons of the importance of each crop, of their vulnerability to climate change, and of the research and policy resources dedicated to each. Especially with respect to climatic susceptibility, these rankings provide a comparative summary based upon the analysis conducted in the four previous EPAR briefs, statistical analyses of historical yield and climate data, and future climate model predictions. According to the indicators analyzed, our research suggests that maize leads the cereal crops in terms of importance within SSA and in terms of research and policy attention. Our analysis of climate conditions and the crop’s physical requirements suggests that many maize-growing areas are likely to move outside the range of ideal temperature and precipitation conditions for maize production. Rice is the third most important crop in terms of consumption dependency, fourth in terms of production, but second only to maize in terms of research funding and FTEs. Sorghum and millet rank second and third in production importance and second and fifth in consumption importance, but rank below maize and rice in terms of FTE researchers. Their role is complicated by the fact that they are often considered inferior goods; SSA consumers often substitute away from sorghum and millet consumption if they are able to do so. Wheat is the least-produced crop of the five, and the second to last in terms of consumption importance. However, it still ranks above millet in terms of FTE researchers.
This brief reviews the literature and empirical evidence on waste extraction and treatment in the developing world. The brief assesses the quantity and quality of research supporting key components of program theory related to the extraction of sludge from on-site sanitation facilities and pre-disposal transport. In general, we find few empirical studies that directly evaluate the assertions of the program theory. Most of the evidence in the literature that addresses the target components of program theory is based upon case studies or general observational and experiential assertions by sanitation experts. Where appropriate, we have identified evidence in the literature according to whether case studies or informal observations formed the basis of the conclusion.
The purpose of this literature review is to provide qualitative and quantitative examples of technologies, constraints and incentives for efficient waste treatment and reuse in Sub-Saharan Africa and Southeast Asia. We present relevant case studies and expert observations and experiences on the nutrient content in urine and feces, contaminants frequently found in untreated sludge and wastewater, waste treatment technologies that may be relevant for low-income countries, risks associated with waste reuse, benefits to resource recovery in agriculture. We further discuss reasons for waste treatment failures, including urbanization, observations on challenges with market-driven reuse in less developed countries, and examples of net-positive energy facilities in Europe and the United States. Much of the evidence presented in the literature relates to wastewater treatment processes or the sludge produced from wastewater treatment as opposed to untreated fecal sludge. However, examples of risks, failures, and opportunities for raw sludge treatment and reuse are discussed when available. In some cases, empirical evidence or case studies were not available for developing countries and alternatives are presented. Overall we found the empirical evidence on waste treatment and reuse in developing countries is quite thin.