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Rwanda Soil Health Trial 2019
RWA -18 -1389Last modified on November 10th, 2025 at 1:57 pm
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Abstract
One Acre Fund (OAF) is an agricultural service provider that provides support for 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.
We evaluated the effects of an SMS campaign in Rwanda that encouraged farmers to adopt recommended soil health inputs, particularly agricultural lime. We first randomized whether individuals in a farmer group received identical messages, diverse messages, or no messages. In the groups that were assigned to receive messages, we randomized individual farmers to receive no message, two messages, or four messages in a six-day time window.
We find that the SMS campaign increased lime adoption by 12% overall but did not significantly affect fertilizer use. Groups that received diverse messages saw higher lime adoption, but this difference is not statistically significant. We find that farmers who received four SMS messages were more likely to adopt recommended inputs than those who received only two messages. -
Status
Completed
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Start date
Q2 Jun 2018
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End date
Q2 Jun 2018
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Experiment Location
Rwanda
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Partner Organization
One Acre Fund (OAF)
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Agricultural season
Season A
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Experiment type
Impact Evaluation
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Sample frame / target population
OAF farmers
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Sample size
99,539
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Outcome type
Input adoption
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Mode of data collection
Partner administrative data
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Research question(s)
What is the best way to utilize SMS messages to spread information about inputs that have the potential to greatly increase agricultural productivity?
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Research theme
Communication technology, Message framing, Message timing and frequency
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Research Design
During the OAF enrollment period for the first agricultural season of 2019 in Rwanda (“A season”), we implemented an SMS campaign encouraging the adoption of recommended soil-health inputs. To test aspects of the campaign, over 80,000 farmers were assigned treatments at both the group and individual levels.
First, farmer groups were randomly assigned at equal probability to one of the following arms:
- Same message within a group (G1): All message recipients in the group received identical messages; the message type was randomly assigned at the group level.
- Diverse messages within a group (G2): Farmers were randomly assigned a message type at the individual level.
- Control group (G0): No farmers received SMS messages.
Four types of messages were used:
- M1: Feed your family
- M2: Social comparison
- M3: Basic
- M4: House metaphor
Second, individual farmers in G1 and G2 were randomly assigned to one of the following groups:
- Low message volume (25%): Farmers received two messages in a six-day time window.
- High message volume (25%): Farmers received four messages in a six-day time window.
- Control (50%): No messages.
Note that this message campaign design is different from that of the 2018 trial, in which messages were separated by three to four days over a two-week period.
For further information on the previous trial, see Rwanda Agricultural Lime Trial 2018
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Results
SMS messaging increased lime adoption by 12% (0.9 percentage points over the control group’s mean of 7.6%); such an increase is consistent with previous findings from the “Rwanda Lime 2018” trial. However, messages had no statistically significant effect on fertilizer adoption—likely because fertilizers are already widely known in the region and were not specifically mentioned in the messages—nor on total soil health input expenditure. While diversifying the message content appeared to boost input adoption, these differences were not statistically significant. We find that farmers who received four SMS messages were more likely to adopt recommended inputs than those who received only two messages. However, this may also be influenced by receiving messages closer to the deadline, or on more beneficial days of the week, in addition to message frequency.
Finally, we observe imprecise, positive spillover effects to farmers who did not receive any messages; the observed magnitudes were well-aligned with previous findings.