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The Impact of Voucher Coupons on the Uptake of Fertilizer and Improved Seeds: Evidence from a Randomized Trial in Mozambique
Last registered on March 14, 2016


Trial Information
General Information
The Impact of Voucher Coupons on the Uptake of Fertilizer and Improved Seeds: Evidence from a Randomized Trial in Mozambique
Initial registration date
March 14, 2016
Last updated
March 14, 2016 7:29 PM EDT
Primary Investigator
University of Michigan
Other Primary Investigator(s)
PI Affiliation
University of California, Davis
PI Affiliation
University of Los Andes
Additional Trial Information
Start date
End date
Secondary IDs
We investigate the impacts of subsidies for technology adoption, and how savings constraints a ect
subsidy impacts. In a theoretical model in which risk-averse households face liquidity constraints as well
as incomplete insurance, alleviating savings constraints could promote persistence of technology adop-
tion over time (dynamic enhancement), or could instead reduce technology investment by encouraging
savings accumulation for other purposes (dynamic substitution). We implemented a eld experiment in
rural Mozambique, randomly assigning households one-time subsidies for adopting modern agricultural
technology (chiefy fertilizer). Entire localities were later randomly assigned programs facilitating formal
savings. In localities with no savings program, subsidy recipients raise their fertilizer use in the subsidized
season and for two subsequent unsubsidized seasons. By contrast, in savings-program localities, subsidy
impacts on fertilizer use do not persist: households shift resources away from fertilizer, instead accumu-
lating savings in formal bank accounts. The savings programs also appear to improve household ability
to cope with risk. These patterns are consistent with the theoretical case of dynamic substitution of
subsidies; alleviating savings constraints leads households to allocate their scarce resources in ways (such
as self-insurance and perhaps other investments) that compete with continued technology investments.
Registration Citation
Carter, Michael, Rachid Laajaj and Dean Yang. 2016. "The Impact of Voucher Coupons on the Uptake of Fertilizer and Improved Seeds: Evidence from a Randomized Trial in Mozambique." AEA RCT Registry. March 14. https://doi.org/10.1257/rct.239-1.0.
Former Citation
Carter, Michael et al. 2016. "The Impact of Voucher Coupons on the Uptake of Fertilizer and Improved Seeds: Evidence from a Randomized Trial in Mozambique." AEA RCT Registry. March 14. http://www.socialscienceregistry.org/trials/239/history/7287.
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Experimental Details
In collaboration with the government of Mozambique, we randomly selected 50% of a sample of small-scale maize farmers to receive voucher coupon that entitled them to receive a 73% subsidy on a package comprised of 100 kilograms of fertilizer and 12.5 kilograms of improved maize seeds. Three treatment groups received different combinations of interventions, and the comparison group did not receive an intervention.
- Treatment group 1, farmers were offered a savings account with standard BOM interest rate.
- Treatment group 2, farmers offered “matched savings” accounts, where farmer received matched funds equal to 50 percent of his or her average savings balance (up to 3,000 MZN , or US$112 ) during a defined match period. (The match rate is the percentage of the average balance in the account that is contributed by the project at the end of the match period, not an annual percentage rate.)
- Treatment group 3, farmers were offered a savings match with a group incentive, where the match rate rises or falls in accordance to the average account balance of the entire group.
Intervention Start Date
Intervention End Date
Primary Outcomes
Primary Outcomes (end points)
Per-capita income and expenditures, maize yields, use of seed varieties and fertilizers, the creation and use of savings accounts, and sustainability of the technology uptake.
Primary Outcomes (explanation)
Secondary Outcomes
Secondary Outcomes (end points)
Secondary Outcomes (explanation)
Experimental Design
Experimental Design
Vouchers for fertilizer were distributed randomly to a sample of farmers. In partnership with Banco Oportunidade de Moçambique (BOM), researchers also randomized offers of one of several different savings accounts interventions, to see how the subsidies and savings accounts complemented one-another.

The sample comprises farmers with access to some type of agricultural extension service, either through an NGO or government entity, so that they have access information on how to use fertilizer if they choose to use it. Researchers worked with two sub-groups of farmers: those who received a voucher for fertilizer, and those who did not. The voucher randomization (VR) sample is comprised of farmers randomly distributed (or not distributed) vouchers for fertilizer. The VR sample enabled researchers to examine the interaction between voucher receipt and savings incentives.

During meetings with farmer groups, project staff discussed the importance of savings and keeping part of one’s harvest proceeds for fertilizer and other agricultural inputs for the next season. Farmers were also given specific instructions about using the fertilizer package for maize, and information on BOM savings services and locations. After farmers completed the baseline survey, savings accounts were offered, and project staff assisted interested farmers in filling out the forms to open an account. Farmers then could make their initial deposit at a BOM branch or a Bancomovil, a mobile bank that services many of the sites.
Experimental Design Details
Randomization Method
Randomization was done in office by computer.
Randomization Unit
Was the treatment clustered?
Experiment Characteristics
Sample size: planned number of clusters
Sample size: planned number of observations
25,000 farmers
Sample size (or number of clusters) by treatment arms
25,000 was the total number of beneficiaries of vouchers (of the government program), but our study included a total of 1,589 participants in the main study and about 250 participants in the pilot study.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
IRB Name
University of Wisconsin, Madison
IRB Approval Date
IRB Approval Number
Post Trial Information
Study Withdrawal
Is the intervention completed?
Is data collection complete?
Data Publication
Data Publication
Is public data available?
Program Files
Program Files
Reports, Papers & Other Materials
Relevant Paper(s)
Newest working paper.
Carter, Michael, Rachid Laajaj, and Dean Yang. "Savings and Subsidies, Separately and Together: Decomposing Effects of a Bundled Anti-Poverty Program." Working Paper, June 2015.
The use of improved seeds and fertilizer contributed to large productivity gains in many parts of the developing world over the last 50 years. And yet this green revolution largely bypassed the African continent, which, over the 1960 to 2000 period, registered the lowest yield increases of all world regions (Evenson and Gollin 2003). According to FAO statistics, African farmers in 2009 used on average only 13 kilograms of fertilizer per hectare, compared with an average of 94 kilograms per hectare in other developing countries. In response to this apparent underutilization of fertilizers, a number of African governments have recently introduced fertilizer subsidies that operate through voucher coupons. Despite the wide-spread adoption of this instrument, the effectiveness of voucher coupons in boosting input use in both the short and the medium term remains largely untested.1 In an effort to fill this evidence gap, we here report initial results from a pilot intervention in Mozambique designed to evaluate the impact of voucher coupons in both in the short and medium terms.
Carter, Michael, Rachid Laajaj, and Dean Yang. 2013. "The Impact of Voucher Coupons on the Uptake of Fertilizer and Improved Seeds: Evidence from a Randomized Trial in Mozambique." American Journal of Agricultural Economics 95(5): 1345-1351.