An adaptive framework to bridge soil health gaps in tropical smallholder farming contexts

Declining soil health threatens food security and the livelihoods of millions of smallholder farmers across the Global South, while increasing their vulnerability to climate change. Yet, existing soil health frameworks are mostly focused on the Global North and fail to guide practical decision-making that is tailored to local contexts. Here, we conceptualize soil health as a foundational pillar of agronomic performance of smallholder crop systems and present a purpose-led and adaptive soil health framework to bridge soil health gaps. Similar to the yield gap concept, we define the ‘soil health gap’ as a benchmark of the soil’s current performance relative to its potential under improved management with respect to ecological functions, including crop production, carbon storage, nutrient cycling and water regulation. Integration of soil chemical, physical, and biological indicators provides a tool to identify the specific soil health gap to be addressed in a given context, and to monitor improvement. The framework follows four iterative phases: (i) Contextualize: characterize local conditions and engage stakeholders; (ii) Diagnose: identify functional soil health constraints using context-sensitive indicators; (iii) Advise: translate diagnostics into actionable recommendations; and (iv) Monitor: track changes in soil health, agronomic and livelihood outcomes. Based on examples from Peru, Kenya and Vietnam we illustrate the applicability of the framework and draw lessons from existing experiences in contrasting smallholder contexts. Finally, we highlight priorities for further research and implementation. The proposed approach bridges scientific knowledge and smallholder realities, proposing a pathway to address soil health gaps and enhance the resilience of tropical smallholder crop systems.