PROBES snapshot: Low-cost portable soil fertility sensors – myth or reality?

This one-page brief, developed by the Digital Transformation Accelerator (DTA) team at the Alliance of Bioversity International and CIAT, is based on a probe led by Oscar Hernán Estrada, Senior Research Associate at the Alliance Bioversity–CIAT. The probe investigates whether emerging low-cost, portable soil fertility sensors can provide sufficiently accurate and reliable nutrient measurements to support fertilizer decision-making for smallholder farmers. Through controlled testing in Guatemala and Colombia, the probe evaluates the performance of handheld Frequency Domain Reflectometry sensors against laboratory benchmarks. Implemented as a safe-to-fail, early-stage experiment, the probe generated important learning by revealing current limitations in accuracy and sensitivity to soil moisture. The brief synthesizes these findings to inform evidence-based decisions on the feasibility, risks, and future research needs of low-cost soil diagnostics before wider investment or deployment.