Research Topics

EPAR Technical Report #303
Publication Date: 08/10/2015
Type: Data Analysis
Abstract

Common estimates of agricultural productivity rely upon crude measures of crop yield, typically defined as the weight harvested of a crop divided by the area harvested. But this common yield measure poorly reflects performance among farm systems combining multiple crops in one area (e.g., intercropping), and also ignores the possibility that farmers might lose crop area between planting and harvest (e.g., partial crop failure). Drawing on detailed plot-level data from Tanzania’s National Panel Survey, our research contrasts measures of smallholder productivity using production per hectare harvested and production per hectare planted.

An initial analysis (Research Brief - Rice Productivity Measurement) looking at rice production finds that yield by area planted differs significantly from yield by area harvested, particularly for smaller farms and female-headed households. OLS regression further reveals different demographic and management-related drivers of variability in yield gains – and thus different implications for policy and development interventions – depending on the yield measurement used. Findings suggest a need to better specify “yield” to more effectively guide agricultural development efforts.

 

EPAR Research Brief #312
Publication Date: 07/30/2015
Type: Literature Review
Abstract

This brief reviews the evidence of realized yield gains by smallholder farmers attributable to the use of high-quality seed and/or improved seed varieties. Our analysis suggests that in most cases, use of improved varieties and/or quality seed is associated with modest yield increases.  In the sample of 395 trials reviewed, positive yield changes accompanied the use of improved variety or quality seed, on average, in 10 out of 12 crops, with rice and cassava as the two exceptions.

EPAR Technical Report #245
Publication Date: 04/10/2015
Type: Data Analysis
Abstract

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.  

EPAR Technical Report #5
Publication Date: 12/15/2008
Type: Literature Review
Abstract

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.