2018 Rwanda Fertilizer Experiment
RWA -18 -1535Last modified on December 19th, 2025 at 10:39 am
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Abstract
One Acre Fund (OAF) is an agricultural service provider that supports smallholder farmers in Africa in accessing agricultural inputs, training, and markets, to help the farmers increase their harvests and income. PxD and OAF began collaborating in 2016 on efforts to increase adoption of agricultural inputs and improve OAF operations in Kenya and Rwanda.
Rwanda’s Ministry of Agriculture (MINAGRI), the Rwandan Agriculture Board (RAB), and OAF conducted a national radio campaign at the end of 2018 to address smallholder farmers’ misconceptions about chemical fertilizer. MINAGRI, RAB, and OAF observed that misconceptions impeded farmers’ adoption of fertilizers, which likely suppressed the yields and income of the farmers.
OAF and PxD conducted a complementary phone-based intervention to send SMS messages to Farmer Promoters (FPs—model farmers elected by other farmers in their village to serve as volunteer extension workers). The SMS messages encouraged FPs to: (i) themselves adopt best practices associated with fertilizer use, and (ii) teach other farmers to do the same. We find that the intervention had a positive and statistically significant effect on the index of the six recommendations for fertilizer use and training we made to FPs in the treatment arms. SMS messages are a low-cost way of making recommendations, and this promising result shows they can effectively modify FP behavior. -
Status
Completed
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Start date
Q4 Oct 2018
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Experiment Location
Rwanda
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Partner Organization
One Acre Fund (OAF)
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Agricultural season
_Multiple seasons
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Experiment type
Impact Evaluation
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Sample frame / target population
Farmer promoters (FPs)
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Sample size
1,828
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Outcome type
Agent performance, Farming practices, Knowledge
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Mode of data collection
In-person survey
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Research question(s)
Can non-financial incentives, in the form of messages of encouragement and appreciation, improve FPs’ farming practices and performance as volunteer extension workers?
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Research theme
Extension agents, Message framing
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Research Design
We randomly assigned FPs to treatment and control experimental arms. FPs in treatment arms received motivational messages whose content was designed to reinforce the content of a national radio campaign that was ongoing at the time. FPs in the control arm did not receive the messages. The experiment was implemented over 40 days.
We randomly assigned our total sample of 3,000 FPs into one of five experimental arms of equal size (n = 600):
Group 0: Control—Received no messages.
Group 1: Basic message (BM)—Received one message every 10 days for a total of four messages over the 40 days. The message contained basic information about fertilizer use and was derived from the radio campaign during that 10-day period.
Group 2: BM + nudge—Received two messages every 10 days for a total of eight messages over the 40 days. The first message was the same BM that Group 1 received. The second message was sent later in the 10-day period as a simple “nudge” message to remind the FPs about the content of the BM.
Group 3: BM + “be a visible leader”—Received two messages every 10 days for a total of eight messages over the 40 days. First, the FPs received the same BM, and subsequently they received a message that encouraged them to “be a visible leader” in their community.
Group 4: BM + “farmer appreciation”—Received two messages every 10 days for a total of eight messages over the 40 days. First, the FPs received the same BM, and subsequently they received a message of encouragement that emphasized that other farmers appreciate the FPs’ work and the role they play in the community.
By comparing Group 0 to Group 1, we estimated the causal effect of receiving a single message on our outcomes of interest: (i) FP adoption of best practices, and (ii) the number of farmers the FP taught to adopt similar practices. By comparing Group 1 to Group 2, we estimated the effect of receiving a single message versus two messages, when the second message was a nudge reminder about the content of the first message. Finally, by comparing groups 3 and 4 to Group 2, we identified whether specific message-framing mattered.
We used a follow-up survey to collect data on FPs’ farming practices and performance as volunteer extension workers, and 1,828 FPs completed the survey.
Our behavior index comprised six outcomes measures:
1. Whether the FP in question used fertilizer on their demonstration plot,
2. Whether the FP in question used fertilizer on their personal plot,
3. Whether the FP in question used both DAP (diammonium phosphate) and urea fertilizers as recommended,
4. The number of farmers the FP trained on the use of fertilizer,
5. The number of farmers the FP trained on their demonstration plot, and
6. Whether the FP correctly answered a question testing their knowledge about fertilizer. -
Results
SMS messages influenced farmer promoter (FP) behavior. Overall, FPs who received SMS messages were more likely to follow our recommendations—both adopting practices on their own plots and training other farmers—compared to the control group. Across all treatment groups, compliance increased by 0.1 standard deviations on our behavior index of six recommended behaviors.
Receiving two messages instead of one may have an effect. FPs who received only the basic message (BM group) showed essentially no change in the behavior index. However, FPs who received the basic message plus additional messages (Groups 2, 3, and 4) showed effects larger than 0.1 standard deviations, though these weren't statistically significant. The different message framings we tested (across Groups 2, 3, and 4) didn't produce meaningfully different outcomes from each other.
For individual outcomes, FPs in Groups 2, 3, and 4, who received BM + additional messages, were more likely to adopt fertilizer for their personal use (p < 0.01, p < 0.1, p < 0.05, respectively). On average, FPs in all treatment groups trained more farmers on fertilizer use than control group FPs did. However, this effect was not statistically significant.