Pulse Brain · Growing Health Evidence Index
Tier 3 — Observational / field trialPeer-reviewed

Designing on-farm trials: an example with interventions to improve micronutrient status of grain crops

R. M. Lark, Muneta G. Manzeke‐Kangara, Job Kihara, Martin R. Broadley

npj Sustainable Agriculture · 2025

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Summary

This paper systematically addresses the methodological challenge of designing effective on-farm experimental networks by evaluating design options for a regional trial assessing micronutrient-biofortification interventions in Ethiopian cereal crops. The authors identified that sufficient farm-scale replication (treating each farm as a complete block) is critical for detecting plausible treatment effects, whilst regional replication at the scale of farm clusters is necessary for precise estimation of treatment means. The study provides a practical framework that could be generalised to design other on-farm experimental networks.

UK applicability

The methodological approach and design principles may be transferable to UK on-farm trial networks, particularly for cereal biofortification or other interventions requiring spatially distributed replication. However, the specific spatial coverage and logistical constraints described are contextual to the Ethiopian setting and would require local adaptation for UK farming conditions.

Key measures

Statistical power (≥0.8), precision of treatment effect estimates, spatial coverage (median distance from random points to experimental sites), farm-scale replication requirements, farm-cluster replication requirements

Outcomes reported

The study assessed design options for on-farm experimental networks to evaluate micronutrient-biofortification interventions in cereal crops, identifying feasible designs to detect treatment effects with statistical power ≥0.8. It examined the spatial coverage and replication requirements needed for both detecting treatment effects and estimating treatment means with precision across a regional network.

Theme
Measurement & metrics
Subject
Micronutrient biofortification
Study type
Research
Study design
Field trial design methodology
Source type
Peer-reviewed study
Status
Published
Geography
Ethiopia
System type
Arable cereals
DOI
10.1038/s44264-025-00101-0
Catalogue ID
SNmozbmdh9-ziwo1r

Topic tags

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