Research Topics

EPAR Technical Report #310
Publication Date: 11/20/2015
Type: Literature Review
Abstract

Cereal yield variability is influenced by initial conditions such as suitability of the farming system for cereal cultivation, current production quantities and yields, and zone-specific potential yields limited by water availability. However, exogenous factors such as national policies, climate, and international market conditions also impact farm-level yields directly or provide incentives or disincentives for farmers to intensify production. We conduct a selective literature review of policy-related drivers of maize yields in Ethiopia, Kenya, Malawi, Rwanda, Tanzania, and Uganda and pair the findings with FAOSTAT data on yield and productivity. This report presents our cumulative findings along with contextual evidence of the hypothesized drivers behind maize yield trends over the past 20 years for the focus countries.

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 #298
Publication Date: 03/23/2015
Type: Literature Review
Abstract

Cassava production is prone to many constraints throughout the production cycle, including biotic, abiotic, and management constraints. This brief reviews the literature on the production impacts of two key cassava stressors: cassava bacterial blight (CBB) and postharvest physiological deterioration (PPD). We summarize available estimates of the frequency and magnitude of these constraints relative to other drivers of cassava production losses that affect smallholder farmers in Sub-Saharan Africa (SSA), review the control strategies proposed in the literature, report on the views of several experts in the field, and identify research gaps where relatively little appears to be known about CBB or PPD yield impacts or best practices for CBB or PPD management. 

EPAR Research Brief #228
Publication Date: 04/18/2014
Type: Literature Review
Abstract

Cassava (Manihot esculenta Crantz) is a widely-grown staple food in the tropical and subtropical regions of Africa, Asia, and Latin America. In this brief we examine the environmental constraints to, and impacts of, smallholder cassava production systems in Sub-Saharan Africa (SSA) and South Asia (SA), noting where the analysis applies to only one of these regions. We highlight crop-environment interactions at three stages of the cassava value chain: pre-production (e.g., land clearing), production (e.g., soil, water, and input use), and post-production (e.g., crop storage). At each stage we emphasize environmental constraints on production (poor soil quality, water scarcity, crop pests, etc.) and also environmental impacts of crop production (e.g., soil erosion, water depletion and pesticide contamination). We then highlight good practices for overcoming environmental constraints and minimizing environmental impacts in smallholder cassava production systems. Evidence on environmental issues in smallholder cassava production is relatively thin, and unevenly distributed across regions. The literature on cassava in South Asian smallholder systems is limited, reflecting a crop of secondary importance (though it is widely found elsewhere in Asia such as South East Asia), in comparison to cassava in much of SSA. The majority of the research summarized in this brief is from SSA. The last row of Table 1 summarizes good practices currently identified in the literature. However, the appropriate strategy in a given situation will vary widely based on contextual factors, such as local environmental conditions, market access, cultural preferences, production practices and the policy environment.

EPAR Technical Report #254
Publication Date: 03/20/2014
Type: Literature Review
Abstract

This overview introduces a series of EPAR briefs in the Agriculture-Environment Series that examine crop-environment interactions for a range of crops in smallholder food production systems in Sub-Saharan Africa (SSA) and South Asia (SA). The briefs cover the following important food crops in those regions; rice (#208), maize (#218), sorghum/millets (#213), sweet potato/yam (#225), and cassava (#228).

Drawing on the academic literature and the field expertise of crop scientists, these briefs highlight crop-environment interactions at three stages of the crop value chain: pre-production (e.g., land clearing and tilling), production (such as water, nutrient and other input use), and post-production (e.g., waste disposal and crop storage). At each stage we emphasize environmental constraints on crop yields (including poor soils, water scarcity, crop pests) and impacts of crop production on the environment (such as soil erosion, water depletion and pest resistance). We then highlight best practices from the literature and from expert experience for minimizing negative environmental impacts in smallholder crop production systems.

This overview (along with the accompanying detailed crop briefs) seeks to provide a framework for stimulating across-crop discussions and informed debates on the full range of crop-environment interactions in agricultural development initiatives.

A paper based on this research series was published in Food Security in August 2015.

EPAR Research Brief #52
Publication Date: 11/09/2009
Type: Literature Review
Abstract

Ecological farming and conventional farming are two approaches to producing food. The term “ecological farming” describes a range of agricultural systems that seek to provide food and environmental and social benefits by using natural processes and local resources rather than off-farm, purchased inputs (commonly referred to as “external inputs”). Recent debate about the merits of ecological farming over conventional methods has centered on each system’s ability to increase production in the context of numerous and varied biophysical and social constraints. A review of the literature suggests that ecological farming can offer some benefits to smallholder farmers, but that specific approaches must be tailored to local climate and soil conditions and availability of labor, training, and organic inputs.

EPAR Research Brief #78
Publication Date: 11/06/2009
Type: Literature Review
Abstract

In the decades following independence in 1960, Côte d’Ivoire stood out as a shining example of economic growth in Sub-Saharan Africa. GDP increased at an annual average of 8.1 percent from 1960 to 1979, led largely by cocoa and coffee exports.  Low export earnings from a fall in world cocoa prices and a heavy public debt burden halted this growth in the 1980s, followed by civil conflict beginning in 1999. Three decades of focus on export crops rather than food crops also left Côte d’Ivoire with a growing food deficit. This literature review examines the state of agriculture in Côte d’Ivoire and the history of government involvement in the agricultural sector. We find that while the country is poised to reemerge from a decade of economic stagnation and civil war after signing the Ouagadougou Political Accord in 2007, the political economy of Côte d’Ivoire is still heavily dependent upon and influenced by the production of cocoa. Cocoa is the top export, and cocoa export taxes provide one of the largest sources of revenue for the Government of Côte d’Ivoire (GoCI). Cocoa is not heavily dependent on fertilizer inputs and growers have increased production by expanding cropland. The small contribution of fertilizer to the production of this essential crop may help explain the GoCI’s low priority on expanding fertilizer production and use. Given that a large part of government revenue comes from the export of cocoa and coffee, the government has chosen to focus resources on crops that increase revenue. Even with the food riots in 2008, the GoCI has not made increasing domestic food production an important focus of agricultural policy.

EPAR Research Brief #76
Publication Date: 11/03/2009
Type: Literature Review
Abstract

In Mozambique, the legacies of colonial rule, socialism and civil war continue to constrain economic growth and agricultural production. Eighty percent of Mozambique’s labor force derives its livelihood from agriculture, but the nation remains a net food importer. The majority of all farmland is cultivated by smallholders whose fertilizer usage and crop yields are among the lowest in Africa. While Mozambique has experienced reasonable economic growth since the end of its civil war in 1992, it remains poor by almost any measure. In this literature review, we examine the state of agriculture in Mozambique, the country’s political history and post-war recovery, and the current fertilizer market. We find evidence that smallholder access to fertilizer in Mozambique is limited by lack of information, affordability, access to credit, a poor business environment, and limited infrastructure. The data demonstrate that increased investment in infrastructure is an important step to improve input and output market access for smallholders. The main government intervention currently impacting smallholder fertilizer use is the Agricultural Sector Public Expenditure Program (PROAGRI) initiative, however, more data is necessary to assess the impact of its policies and programs.

EPAR Research Brief #77
Publication Date: 11/03/2009
Type: Literature Review
Abstract

Agriculture is the most important sector in the Ghanaian economy. In 2008, it accounted for over 32 percent of GDP and employed over half of the labor force. Economic development in Ghana has historically been dependent on the success of agriculture, particularly the main export crop, cocoa. Despite the sector’s importance, Ghanaian farmers have one of the lowest fertilizer application rates in Sub-Saharan Africa. The combination of a dominant agricultural sector, nutrient-poor soils, low fertilizer use among smallholder farmers, and the absence of locally produced inorganic fertilizers has prompted the government of Ghana (GoG) to intervene in the fertilizer market. This literature review examines the state of agriculture in Ghana, the history of the fertilizer market, and the current market structure. We find that the GoG has been a major actor in the inorganic fertilizer market over the past 50 years, from exercising total control of the domestic supply chain in the 1960s and 1970s to more indirect interventions in later years. In recent years, agricultural growth has averaged 5.5 percent as compared to 5.2 percent growth in the rest of the economy.  However, most of this growth has been due to land expansion and favorable weather conditions rather than increased productivity.  Increased fertilizer use among smallholder farmers has the potential to contribute to future agricultural growth and continued economic success.

EPAR Research Brief #75
Publication Date: 11/02/2009
Type: Literature Review
Abstract

In Tanzania, agriculture represents approximately 50 percent of GDP, 80 percent of rural employment, and over 50 percent of the foreign exchange earnings. Yet poor soil fertility and resulting low productivity contribute to low economic growth and widespread poverty. Chemical fertilizer has the potential to contribute to crop yield increases. Yet high prices and weaknesses in the fertilizer market keep fertilizer use low. This literature review examines the history of government interventions that have intended to increase access to fertilizers, and reviews current policies, market structure, and challenges that contribute to the present conditions. We find that despite numerous strategies over the last fifty years, from heavy government involvement to liberalization, major weaknesses in Tanzania’s fertilizer market prevent efficient use of fertilizer. High transportation costs, low knowledge level of farmers and agrodealers, unavailability of improved seed, and limited access to credit all contribute to the market’s problems. The government’s current framework, the Tanzania Agriculture Input Partnership (TAIP), acknowledges this interconnectedness by targeting multiple components of the market. This model could help Tanzania tailor solutions relevant to specific road, soil, and market conditions of different areas of the country, contributing to enhanced food security and economic growth.