Linking geospatial science with local knowledge systems to support soil security in African critical zones

The soil security situation in Africa continues to worsen endangering both food production, population health and Sustainable Development Goal (SDG) achievement. While soil degradation and contamination happen in local areas, policies remain largely at national levels or beyond. This situation exists because of an organizational dependence on low-resolution top-down geospatial information which fails to detect the micro-scale mechanisms operating within African critical zones.
The study combines data from the Critical Zones Africa (CZA) project which studied five African countries including Ethiopia, Tanzania, Malawi, Zimbabwe and South Africa to understand the reasons behind different soil policies that do not match smallholder farming practices. The study evaluates the advantages and weaknesses of multiple geospatial tools through a systematic literature review framework to analyze land-use and land-cover mapping and vegetation indices and erosion models and hydrological simulations.
The study results demonstrate that geospatial methods successfully detect large-scale patterns of land deterioration and soil erosion vulnerability, but they do not solve essential soil management problems which need higher resolution at both farm and community levels. The main blind spots exist in Ethiopia where geochemical contamination occurs, and Tanzania faces groundwater contamination because of agricultural land growth and Malawi experiences soil degradation because of deforestation and Zimbabwe and South Africa struggle with water system nutrient waste. The evaluation process for all cases shows that soil investment choices and governance decisions face limitations because the available data does not match what happens in the field.
The achievement of soil security in African critical zones needs policymakers to adopt evidence-based integrated systems which operate at suitable scales. We recommend three essential measures which include: (i) providing all of Africa with access to detailed geospatial information (ii) African soil science education needs to be revitalized while laboratory facilities must be restored (iii) All fields must undergo ground-truthing assessments while local communities need to participate in the process. The study also recommends that proposed work program for AMCEN during 2026-2028 should enable UNEP to provide high-resolution data access which will help develop soil policies that fit the specific conditions of African territories.