Evans School Policy Analysis & Research Group (EPAR)

A farmer’s decision of how much land to dedicate to each crop reflects their farming options at the extensive and intensive margins. The extensive margin represents the total amount of agricultural land area that a farmer has available in a given year (referred to interchangeably as ‘farm size’ or ‘agricultural land’). A farmer increases land use on the extensive margin by planting on new agricultural land. The intensive margin represents area planted of crops as a proportion of total farm size. A farmer increases the intensive margin by increasing output within a fixed area. This analysis examines cropping patterns for households in Tanzania between 2008 and 2010 using data from the Tanzania National Panel Survey (TZNPS).  This brief describes changes in farm size, total area planted, and area planted of select annual crops to highlight the dynamic nature of farmer’s cropping choices for a sample population of 2,246 agricultural households that reported having any agricultural land in 2008 or 2010. Throughout the brief, we present summary statistics at the national level and compare them with household-level data to show how results vary depending on how the sub-population is defined and how average measures can mask household level changes. We analyze these questions in the context of smallholders (defined as households with total agricultural land area as less than two hectares) and farming systems.  

Aid donors are interested in the arguments for allocating aid via bilateral versus multilateral channels, and specifically in understanding which channel is more “effective” at supporting positive development and social outcomes. We contribute to the literature on this subject by summarizing recent OECD data on aid flows and reviewing the theoretical arguments from the aid literature on the different characteristics supporting effectiveness of bilateral versus multilateral aid. We then review the empirical literature, analyzing 40 papers that study the effectiveness of different aid channels on various outcomes. Many studies do not directly compare the effectiveness of aid channels, and the studies vary in how aid channels are defined, measured, and evaluated. Further, these studies do not directly test the hypothesized advantages of one channel of aid versus another; rather they test bilateral versus multilateral aid flows associations with development outcomes, assuming some causal mechanism is at work to explain differences in impact. We evaluate studies reporting the impacts of aid on GDP growth, governance, government investment spending, health, the HDI, poverty, and private investment, and find no consistent evidence that either bilateral or multilateral aid is more effective. The lack of conclusive evidence supporting either aid channel is likely related to differences in the methodologies of the studies included in this review, but may also be due to differences in how the theoretical arguments for the effectiveness of either channel apply in different circumstances.

This report reviews the literature on textural attributes of Root, Tuber, and Banana (RTB) crops with a focus on studies relevant for crop research and development in Sub-Saharan Africa. The texture of cooked root and tuber crops is often cited as a primary determinant of consumer acceptability of new varieties, including those produced through traditional breeding and through genetic engineering. Evidence from texture-related consumer preferences studies for the RTB crops tropical yam, sweetpotato, banana/plantain, cassava, and potato, as well as the results of physicochemical and genetic studies detailing the current scientific understanding of drivers of textural traits, is reviewed and synthesized.

As our understanding of the impacts of hidden hunger on human nutrition grows, understanding the link between fertilizer use and human nutrition becomes increasingly important. This report presents an analysis of both grey and peer-reviewed literature on the effects of fertilizer use on nutritional quality of food, particularly the staples of maize, rice, wheat, cassava and legumes. We find that some nutrient deficiencies, such as zinc, can be effectively addressed through fertilizer use while others, such as iron deficiency, are more difficult to address.  Promising breakthroughs with fortified and complete fertilizers present the opportunity to correct multiple deficiencies. Current fertilizer products exist that, when applied with the proper agronomic methods, can have a significant effect on nutrition in the developing world.  However, it is important to recognize that there are many factors in the developing world that have the potential to inhibit the benefits of fertilizer for human nutrition.  Two significant factors are poor farmers’ difficulty in procuring the correct product and the relative sophistication required to apply fertilizers at the correct amounts and time to achieve desired results.  In addition, researchers have not focused on fertilizer and nutrition studies until recently, particularly micronutrient fertilizer studies, and few studies specifically study the impacts of fertilizer on human nutrition.  More research needs to be done to understand the most effective combinations and techniques, and to understand whether these methods truly increase the amount of nutrients bioavailable to humans.