The Impact of Site Specific Soil Fertility Recommendations: experimental evidence from Malawi

Last registered on September 12, 2024
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Pre-Trial

Trial Information

General Information

Title
The Impact of Site Specific Soil Fertility Recommendations: experimental evidence from Malawi
RCT ID
AEARCTR-0014293
Initial registration date
September 02, 2024

Initial registration date is when the trial was registered.

It corresponds to when the registration was submitted to the Registry to be reviewed for publication.

First published
September 12, 2024, 5:24 PM EDT

First published corresponds to when the trial was first made public on the Registry after being reviewed.

Locations

Country
Malawi
Region
Kasungu, Ntchisi, Dowa, and Mchinji

Primary Investigator

Name
Bjorn Van Campenhout
Affiliation
Ifpri
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Other Primary Investigator(s)

PI Name
Joachim De Weerdt
PI Affiliation
IFPRI
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PI Name
Thomas Assefa
PI Affiliation
IFPRI
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PI Name
David Spielman
PI Affiliation
IFPRI
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PI Name
Edwin Siyame
PI Affiliation
IFPRI
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PI Name
Richard Ariong
PI Affiliation
IFPRI
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Additional Trial Information

Status
In development
Start date
2024-09-15
End date
2025-04-30
Keywords
Agriculture, Finance & Microfinance
Additional Keywords
inorganic fertilizer, soil test, decision support tools, agricultural extension, fertilizer subsidies.
JEL code(s)
O33, Q12, Q16
Secondary IDs
699017.002.006
Prior work
This trial is based on or builds upon one or more prior RCTs.
Abstract
Raising agricultural productivity among smallholder farmers in Sub-Saharan Africa is widely recognized as an important component of inclusive wealth creation and structural transformation. Central to this endeavor will be the adoption of sustainable soil and land management to improve the sustainability, resilience and productivity of agriculture. As such, government advise farmers to increase soil productivity by embracing the use of fertilizers and implement proper soil health management practices. However, these recommendations mostly come in the form of blanket one-size-fits-all recommendations that ignore heterogeneity in soil characteristics that individual farmers face. Using a cluster randomize control trial, we evaluate the impact of a bundled intervention that involves offering farmers a soil test on a plot they select and, using the results of this soil test, provide them with tailored advise on soil management to attain a desired yield for a particular crop the farmer chooses to plant on the plot. Furthermore, we also explore resources constraints as a potential barrier to the adoption of site specific fertilizer blends by adding a subsidy.
External Link(s)
link to the project github repository

Registration Citation

Citation
De Weerdt, Joachim et al. 2024. "The Impact of Site Specific Soil Fertility Recommendations: experimental evidence from Malawi." AEA RCT Registry. September 12. https://doi.org/10.1257/rct.14293-1.0
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Experimental Details

Interventions

Intervention(s)
A first treatment (T1) entails a soil report based on a soil test conducted on a plot chosen by the farmer. This report includes key characteristics of the soil, along with a customized recommendation for a fertilizer blend tailored to the specific crop selected by the farmer. The soil report is delivered to the farmer by an extension agent that explains the soil report.
A second treatment (T2) is a subsidy will be provided to farmers that can be used to purchase the recommended fertilizer blend.
Intervention Start Date
2024-09-22
Intervention End Date
2024-10-13

Primary Outcomes

Primary Outcomes (end points)
yield, profit.
Primary Outcomes (explanation)
outcomes are measured at the household level (as the treatment may affect which plot is chosen by the farmer which complicates identifying an appropriate plot in the control group). In other words, we will collect information on all plots.

Secondary Outcomes

Secondary Outcomes (end points)
crops grown by the farmer, soil health management practices used by the farmer (eg fertilizer blends used)
Secondary Outcomes (explanation)
application error (soil management practices used versus those recommended)

Experimental Design

Experimental Design
Cluster randomized control trail with incremental treatments (1 control arm, one T1 arm, and one T1+T2 arm)
Experimental Design Details
Not available
Randomization Method
randomization done in office by a computer
Randomization Unit
villages
Was the treatment clustered?
Yes

Experiment Characteristics

Sample size: planned number of clusters
113 villages
Sample size: planned number of observations
2034 (16 households in 113 villages plus 2 households in 113 villages to account for attrition)
Sample size (or number of clusters) by treatment arms
41 villages in T1, 42 villages in T2 and 30 villages in the Control
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Simulation was used to determine sample size. We simulated treatment effects by drawing samples from real data collected in April and May 2024. We model 13 percent increase over baseline yield (average yield is 2,574 kilogram per hectare with standard deviation of 1145) for both T1 and T2.
Supporting Documents and Materials
IRB

Institutional Review Boards (IRBs)

IRB Name
IRB Approval Date
IRB Approval Number
Analysis Plan