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Nudging Farmers to Use Fertilizer: Experimental Evidence from Kenya
Last registered on November 01, 2016

Pre-Trial

Trial Information
General Information
Title
Nudging Farmers to Use Fertilizer: Experimental Evidence from Kenya
RCT ID
AEARCTR-0001748
Initial registration date
November 01, 2016
Last updated
November 01, 2016 4:49 AM EDT
Location(s)
Region
Primary Investigator
Affiliation
University of California, Santa Cruz
Other Primary Investigator(s)
PI Affiliation
Harvard University
PI Affiliation
Massachusetts Institute of Technology
Additional Trial Information
Status
Completed
Start date
2003-01-01
End date
2005-12-31
Secondary IDs
Abstract
We model farmers as facing small fixed costs of purchasing fertilizer and assume some are stochastically present biased and not fully sophisticated about this bias. Such farmers may procrastinate, postponing fertilizer purchases until later periods, when they may be too impatient to purchase fertilizer. Consistent with the model, many farmers in Western Kenya fail to take advantage of apparently profitable fertilizer investments, but they do invest in response to small, time-limited discounts on the cost of acquiring fertilizer (free delivery) just after harvest. Calibration suggests that this policy can yield higher welfare than either laissez-faire policies or heavy subsidies.
External Link(s)
Registration Citation
Citation
Duflo, Esther, Michael Kremer and Jonathan Robinson. 2016. "Nudging Farmers to Use Fertilizer: Experimental Evidence from Kenya." AEA RCT Registry. November 01. https://doi.org/10.1257/rct.1748-1.0
Former Citation
Duflo, Esther, Michael Kremer and Jonathan Robinson. 2016. "Nudging Farmers to Use Fertilizer: Experimental Evidence from Kenya." AEA RCT Registry. November 01. https://www.socialscienceregistry.org/trials/1748/history/11575
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Experimental Details
Interventions
Intervention(s)
Basic Savings and Fertilizer Incentive (SAFI): In the first season, a field officer visited farmers immediately after the harvest and offered to sell them a voucher for fertilizer, at the regular price, with free delivery later in the season. The farmer had to decide during the visit whether or not to participate in the program, and could buy any amount of fertilizer. In the second season, a new group of farmers was selected to receive the basic SAFI treatment. The second season also included additional interventions, structured as follows:

SAFI with ex ante choice of timing: A field officer visited the farmers before the harvest and offered them the opportunity to decide when, during the next growing season, they wanted the officer to return to offer them the SAFI program. They were then visited at the specified time, and offered a chance to buy a voucher for future fertilizer use (as in the Basic SAFI program, as described above).

Free delivery visit later in the season: Same as the basic SAFI intervention, but farmers were visited later in the season. A field officer visited farmers 2-4 months after the harvest (when it is time to apply fertilizer as a top-dressing to the next crop), and offered them the opportunity to buy fertilizer, at the regular price, with free delivery.

Subsidy later in season: A field officer visited the farmers 2-4 months after the harvest (when it is time to apply fertilizer to the next crop) and offered to sell them fertilizer, at a 50 percent subsidy, with free delivery.

In each of the intervention groups, as well as in the comparison group, a random subset of farmers was offered the option to sell a set quantity of maize at a favorable price to the field officer before the program took place.
Intervention Start Date
2003-01-01
Intervention End Date
2004-12-31
Primary Outcomes
Primary Outcomes (end points)
Fertilizer use (by season)
Primary Outcomes (explanation)
Secondary Outcomes
Secondary Outcomes (end points)
Secondary Outcomes (explanation)
Experimental Design
Experimental Design
In collaboration with the NGO International Child Support (ICS), researchers designed an intervention to test if providing mechanisms to save harvest income for future fertilizer purchase could be effective in increasing usage. The intervention was called the Savings and Fertilizer Initiative (SAFI). The design of the experiment allowed researchers to test the impact of the SAFI program against various other strategies to improve usage, in particular fertilizer subsidies. The project also investigates whether difficulty in saving harvest income until the time that inputs are needed is a significant barrier to adoption. Finally, the option given to farmers to sell maize before the program took place tests the alternative hypothesis that the SAFI program was seen by the farmers just as a safer way to protect their savings than available alternatives.
Experimental Design Details
Randomization Method
STATA
Randomization Unit
Individual (farmer)
Was the treatment clustered?
No
Experiment Characteristics
Sample size: planned number of clusters
1,634 farmers
Sample size: planned number of observations
1,634 farmers
Sample size (or number of clusters) by treatment arms
Season 1 -
Basic SAFI: 204 farmers
Control: 673 farmers

Season 2 -
Basic SAFI: 179 farmers
Basic SAFI with ex ante choice: 208 farmers
Normal price fertilizer with free delivery at top dressing time: 135 farmers
Half price fertilizer with free delivery at top dressing time: 133 farmers
Control: 102 farmers
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
IRB
INSTITUTIONAL REVIEW BOARDS (IRBs)
IRB Name
IRB Approval Date
IRB Approval Number
Post-Trial
Post Trial Information
Study Withdrawal
Intervention
Is the intervention completed?
Yes
Intervention Completion Date
December 31, 2004, 12:00 AM +00:00
Is data collection complete?
Yes
Data Collection Completion Date
December 31, 2005, 12:00 AM +00:00
Final Sample Size: Number of Clusters (Unit of Randomization)
924 farmers
Was attrition correlated with treatment status?
No
Final Sample Size: Total Number of Observations
924 farmers
Final Sample Size (or Number of Clusters) by Treatment Arms
Data Publication
Data Publication
Is public data available?
Yes
Program Files
Program Files
Reports and Papers
Preliminary Reports
Relevant Papers
Abstract

Nudging Farmers to Use Fertilizer: Theory and Experimental Evidence from Kenya
Citation
Duflo, Esther, Michael Kremer and Jonathan Robinson. 2011. "Nudging Farmers to Use Fertilizer: Theory and Experimental Evidence from Kenya." American Economic Review, 101(6): 2350-90.