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Erick Boy

researcher spotlight

Erick Boy

Erick Boy is the Chief Nutritionist in the HarvestPlus section of the Innovation Policy and Scaling Unit. As head of nutrition for the HarvestPlus Program since 2008, he has led research that has generated scientific evidence on biofortified staple crops as efficacious and effective interventions to help address iron, vitamin A, and zinc deficiency in sub-Saharan Africa, Latin America, and South Asia.

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experts

Innovation Policy and Scaling

Thomas Assefa

Associate Research Fellow

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Bio

Thomas Woldu Assefa is an Associate Research Fellow in the Innovation Policy and Scaling Unit. He is a development economist whose research interests include agricultural technology adoption, rural development, agricultural transformation, behavioral economics, agricultural extension and advisory services, food and nutrition security, and survey methods and measurements. Most of his research involves experimental and quasi-experimental impact evaluation methods, and he has extensive experience in designing and implementing large-scale household surveys and randomized controlled trials. In his recent work, Thomas has focused on understanding smallholder farmers’ fertilizer adoption decisions and innovative methods to minimize measurement errors in development economics research.

Before joining IFPRI, he worked as a postdoctoral research fellow at the University of Georgia, as a consultant for the World Bank and the Food and Agriculture Organization of the United Nations (FAO), and as an IMMANA postdoctoral research fellow in a program administered by Tufts University. Thomas received his MSc from the Norwegian University of Life Sciences and holds a PhD from the University of Georgia, US.

Google Scholar Citations

Publications

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Journal Article

Fertilizer demand and profitability amid global fuel-food-fertilizer crisis: Evidence from Ethiopia

2025Assefa, Thomas; Berhane, Guush; Abate, Gashaw T.; Abay, Kibrom A.
Details

Fertilizer demand and profitability amid global fuel-food-fertilizer crisis: Evidence from Ethiopia

We assess fertilizer demand and profitability in Ethiopia in the face of the recent global fuel–food–fertilizer price crisis and other domestic shocks. We first examine farmers’ response to changes in both fertilizer and food prices by estimating price elasticity of demand. We then evaluate the profitability of fertilizer by computing average value–cost ratios (AVCRs) associated with fertilizer application before and after these crises. We use detailed longitudinal household survey data collected in three rounds, covering both pre-crisis (2016 and 2019) and post-crisis (2023) production periods, focusing on three main staple crops in Ethiopia (maize, teff, and wheat). Our analysis shows that fertilizer adoption, and yield levels were increasing until the recent crises, but these trends have been halted by these crises. We also find slightly larger fertilizer price elasticity of demand estimates than previous estimates, ranging between −0.40 and −1.12, which vary across crops. We find that farmers are more responsive to fertilizer prices than to output prices. Farmers’ response to increases in staple prices was statistically insignificant and hence not as strong as theoretically perceived. Households with smaller farm sizes are relatively more responsive to changes in fertilizer prices. Finally, we show important dynamics in the profitability of chemical fertilizer. While the AVCRs show profitable trends for most crops, the share of farmers with profitable AVCRs declined following the fertilizer price surges. Our findings offer important insights for policy focusing on mitigating the adverse effects of fertilizer price shocks.

Year published

2025

Authors

Assefa, Thomas; Berhane, Guush; Abate, Gashaw T.; Abay, Kibrom A.

Citation

Assefa, Thomas; Berhane, Guush; Abate, Gashaw T.; and Abay, Kibrom A. 2025. Fertilizer demand and profitability amid global fuel-food-fertilizer crisis: Evidence from Ethiopia. Food Policy 133 (May 2025): 102785. https://doi.org/10.1016/j.foodpol.2024.102785

Country/Region

Ethiopia

Keywords

Africa; Sub-saharan Africa; Eastern Africa; Fertilizers; Prices; Farmers; Household Surveys; Maize; Teff; Wheat; Yields

Language

English

Access/Licence

Open AccessCC-BY-4.0

Links

https://doi.org/10.1016/j.foodpol.2024.102785 Source record

Project

National Policies and Strategies

Record type

Journal Article

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Journal Article

Evaluating large-scale government investments in fertilizer adoption: The Ethiopian experience

2025Assefa, Thomas; McCullough, Ellen; Berhane, Guush
Details

Evaluating large-scale government investments in fertilizer adoption: The Ethiopian experience

We evaluate the impact of a large Government of Ethiopia intervention to raise fertilizer supply by establishing five fertilizer blending facilities supplying fertilizers tailored to local soil nutrient profiles. We rely on the phased geographic rollout of blending facility establishment to identify the causal effect on fertilizer use, application rates, crop yields, gross crop revenue, and household consumption. Combining effects of multiple treatment periods, each estimated using a doubly robust difference-in-difference model, we find that the blending facilities increased the probability that farmers adopt the new blended fertilizers by 22 percentage points and increased application rates by 17 kg/ha (baseline adoption was zero). The facilities mostly induced farmers who previously used DAP to switch to NPS, and we find large decreases in DAP adoption (by 22 percentage points, 47% of the control group base mean) and application rates (16 kg/ha, 52% of the control group base mean) yet no impact on overall fertilizer adoption or application rates. Though the new blended fertilizers were expected to perform better, there is no evidence they improved crop yields, crop gross revenue, or household consumption. The effect of the intervention was more pronounced (with larger increases in NPS use and larger decreases in DAP use) for farms located near demonstration plots, which the Government used to train farmers about the agronomic response to the new fertilizers. We confirm results using three large-scale longitudinal datasets and show that they are robust to choices of specification, treatment definition, and inference assumptions. JEL classification: O12, O13, Q16, Q18

Year published

2025

Authors

Assefa, Thomas; McCullough, Ellen; Berhane, Guush

Citation

Assefa, Thomas; McCullough, Ellen; and Berhane, Guush. Evaluating large-scale government investments in fertilizer adoption: The Ethiopian experience. American Journal of Agricultural Economics. Article in press. FIrst published online July 31, 2025. https://doi.org/10.1111/ajae.70007

Country/Region

Ethiopia

Keywords

Africa; Eastern Africa; Sub-saharan Africa; Agricultural Extension; Agricultural Technology; Fertilizer; Crop Yield; Market Access; Soil Fertility

Language

English

Access/Licence

Open AccessCC-BY-4.0

Links

https://doi.org/10.1111/ajae.70007 Source record

Record type

Journal Article

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Other

The impact of site-specific soil fertility recommendations: Experimental evidence from Malawi

2024Van Campenhout, Bjorn; De Weerdt, Joachim; Assefa, Thomas; Spielman, David J.; Siyame, Edwin W. P.; Ariong, Richard M.; Atkinson, Jonathan
Details

The impact of site-specific soil fertility recommendations: Experimental evidence from Malawi

Raising agricultural productivity among smallholder farmers in Sub-Saharan Africa is widely recognized as an important component of inclusive wealth creation and structural transformation. Central to this endeavor will be the adoption of sustainable soil and land management to improve the sustainability, resilience and productivity of agriculture. As such, government advise farmers to increase soil productivity by embracing the use of fertilizers and implement proper soil health management practices. However, these recommendations mostly come in the form of blanket one-size-fits-all recommendations that ignore heterogeneity in soil characteristics that individual farmers face. Using a cluster randomize control trial, we evaluate the impact of a bundled intervention that involves offering farmers a soil test on a plot they select and, using the results of this soil test, provide them with tailored advise on soil management to attain a desired yield for a particular crop the farmer chooses to plant on the plot. Furthermore, we also explore resources constraints as a potential barrier to the adoption of site specific fertilizer blends by adding a subsidy. JEL codes: O33, Q12, Q16

Year published

2024

Authors

Van Campenhout, Bjorn; De Weerdt, Joachim; Assefa, Thomas; Spielman, David J.; Siyame, Edwin W. P.; Ariong, Richard M.; Atkinson, Jonathan

Citation

Van Campenhout, Bjorn; De Weerdt, Joachim; Assefa, Thomas; Spielman, David J.; Siyame, Edwin; Ariong, Richard; and Atkinson, Jonathan. 2024. The impact of site-specific soil fertility recommendations: Experimental evidence from Malawi. AEA RCT Registry. https://doi.org/10.1257/rct.14293-2.0

Country/Region

Malawi

Keywords

Africa; Agricultural Extension; Decision-support Systems; Inorganic Fertilizer; Soil Analysis

Language

English

Access/Licence

Limited Access

Links

https://doi.org/10.1257/rct.14293-2.0 Source record

Record type

Other

News

June 12, 2025 | Press Release

New special issue of Food Policy examines fertilizer and soil health policies in the wake of global crises

Key findings were presented and discussed during the IFPRI policy seminar on June 11.