Messaging Approaches to Promote Nutritious Vegetables
KEN -19 -1359Last modified on October 29th, 2025 at 12:03 pm
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Abstract
One Acre Fund (OAF) is an agricultural service provider that provides support for smallholder farmers in Africa to access agricultural inputs, training, and markets, to help the farmers increase their harvests and income. PAD and OAF began collaborating in 2016 on efforts to increase adoption of agricultural inputs and improve OAF operations in Kenya and Rwanda.
Micronutrient deficiencies are widespread in rural Kenya. According to the Kenya National Micronutrient Survey conducted in 2011, 83.3% of preschool-age children in rural areas suffered from zinc deficiency, and 26.3% from anemia. Deficiencies in key micronutrients like iron and zinc can hinder growth and cognitive function and are major contributors to child and maternal mortality in the developing world, particularly in sub-Saharan Africa. In partnership with OAF, we evaluate one approach to addressing this issue: an SMS campaign informing OAF farmers about the agronomic and nutritional benefits of zinc-fortified beans and nutritious vegetables. OAF offers the opportunity for farmers to buy these seed varieties on credit.
We find that SMS messages increased adoption of zinc-fortified beans and recommended vegetables by 1.8 and 1.0 percentage points (pp), respectively. These increases constitute increases over the control group of 89.3% (control mean 2%) and 3.4% (control mean 29.2%) in each recommended input. Based on the cost of SMS dissemination at OAF, we estimate that the intervention increased adoption at a cost of $0.57 and $0.97 per additional farmer adopting zinc-fortified beans and recommended vegetables, respectively.
Furthermore, we find significant differences in adoption outcomes between different message framings: Content that emphasized agronomic properties and yield-potential was particularly effective at encouraging bean adoption, while messaging that focused on preventing anemia was particularly effective at encouraging vegetable adoption. We also tested if varying messages, both over time and across neighboring farmers, could facilitate social learning and increase adoption, but we find no evidence that message variation increased adoption. Lastly, we explore heterogeneity by gender, and find that, while adoption of zinc-fortified beans was significantly higher among women in the control group, men increased their adoption more than women did as a result of the treatment; we do not find significant gender heterogeneity in vegetable adoption. -
Status
Completed
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Start date
Q3 Sep 2019
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End date
Q1 Mar 2020
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Experiment Location
Kenya
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Partner Organization
One Acre Fund (OAF)
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Agricultural season
Long Rains
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Experiment type
Impact Evaluation
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Sample frame / target population
OAF farmers
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Sample size
386,467
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Outcome type
Input adoption
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Mode of data collection
Partner administrative data, Phone survey
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Research question(s)/hypotheses
1. Will SMS messages increase the adoption of zinc-fortified beans (KMR 13) and nutritious vegetables by OAF farmers?
2. Which messages are most effective?
3. Does varying messages over time or across OAF group-members increase adoption?
4. Is there heterogeneity in effects by gender? -
Research theme
Communication technology, Gender, Message framing, Message timing and frequency, Social learning
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Research design notes
The sample of 386,467 farmers, from 53,891 OAF farmer groups, was randomized into treatment (80%) or control (20%). Treated farmers received two messages, one about zinc-fortified beans (KMR 13) and one about vegetables, each week for three weeks. Messages were varied in two dimensions.
First, we randomly assigned farmers to receive either identical messages about each crop over three weeks or differently framed messages about each crop emphasizing, for example, anemia prevention, availability of training, or benefits for children during the message campaign. Second, we randomized message variation at the group level: In some groups, each farmer in a group received the identical message in any given week; in other farmer groups, the message content was randomized across members. This created four experimental groups.
At the individual level, we tested which is more effective: sending different messages or focusing on reiterating and reinforcing the same content by repeating the same message. Additionally, we used a phone survey to measure whether message variation within groups led to information-sharing and discussion about the recommended products between group members, and ultimately to adoption of input from OAF. Lastly, in order to increase conversation within groups and increase the likelihood that farmers in different-message groups would realize that their group members had received different content, we sent a social-nudge message to half of all treated farmer groups. The message encouraged farmers to share the messages with their group members, and we evaluated its effect.
Message text as follows:
Beans 1 Nutrition: “Hello [Name]! FAIDA (NUTRITIOUS) BEANS have important vitamins and minerals for everyone’s health. Try 1/4 acre from OAF this season for only KES 1250!”
Beans 2 Trainings: “Hello [Name]! Order FAIDA (NUTRITIOUS) BEANS from OAF, and we will train you how to get good yields! Try 1/4 acre this season for only KES 1250!”
Beans 3 Agronomic: “Hello [Name]! FAIDA (NUTRITIOUS) BEANS are suitable for your area, mature in 80-85 days and yield 6-13 bags per acre! Try 1/4 acre from OAF for KES 1250!Vegetables 1 Nutrition: “Hi [Name]! Many Kenyans are at risk of anemia! OAF is offering sukuma, spinach, saga and managu, which prevent anemia and add strength, for a low price.”
Vegetables 2 Trainings: “Hi [Name]! OAF is offering sukuma, spinach, saga and managu. We have certified seeds and will train you on these crops so you get good yields!”
Vegetables 3 Children: “Hi [Name]! Children who eat leafy vegetables grow strong and perform better at school! OAF is offering sukuma, spinach, saga and managu for a low price!” -
Results
The SMS campaign increased the adoption of KMR 13 beans and recommended vegetables by 1.8 pp (89.3% over the control mean of 2%) and 1.0 pp (3% over the control mean of 29%), respectively.
Across our sample, these effects imply that the program led to an estimated 4,965 additional KMR 13 adopters and an additional 2,923 adopters of the recommended vegetable varieties, at an estimated cost of US$5,654 to send the messages. With simple back-of-the envelope calculations, we estimate that the cost per additional KMR 13 adopter was $0.57 and the cost per additional vegetable adopter was $0.97.
With the bean messages, the agronomic message led to significantly higher bean adoption than either of the other messages, and receiving the same message three times was marginally better than receiving three different bean messages over the course of the campaign. With the vegetable content, the message emphasizing that “children who eat leafy vegetables grow strong and perform better at school” had no effect on vegetable adoption. We do not find any evidence that varying message content, either within groups or over time, increased input adoption. Regarding KMR 13 bean adoption, all four groups are very similar, ranging by no more than 0.1 pp. Results for individual-level message variation were also insignificant. Furthermore, we find no evidence that the messages affected the amount of information sharing, which was an upstream indicator measured in several different ways in our phone survey. We do not find any significant heterogeneous effects by gender in vegetable adoption.