The State of Soil Degradation in Sub-Saharan Africa: Baselines, Trajectories, and Solutions

TLDR

Soil degradation in sub‑Saharan Africa is driven mainly by expanding agriculture, yet its extent and rate remain uncertain due to limited reliable data, threatening food production and ecosystem services. The study seeks to identify cross‑sectoral solutions and direct future research on how degradation alters ecosystem services and how soils can be managed in SSA. The authors synthesized broad‑scale studies that quantified multiple soil degradation indicators across SSA. The synthesis revealed widespread degradation, with pH and cation exchange capacity declining linearly and soil organic carbon and yields declining non‑linearly.

Abstract

The primary cause of soil degradation in sub-Saharan Africa (SSA) is expansion and intensification of agriculture in efforts to feed its growing population. Effective solutions will support resilient systems, and must cut across agricultural, environmental, and socioeconomic objectives. While many studies compare and contrast the effects of different management practices on soil properties, soil degradation can only be evaluated within a specific temporal and spatial context using multiple indicators. The extent and rate of soil degradation in SSA is still under debate as there are no reliable data, just gross estimates. Nevertheless, certain soils are losing their ability to provide food and essential ecosystem services, and we know that soil fertility depletion is the primary cause. We synthesize data from studies that examined degradation in SSA at broad spatial and temporal scales and quantified multiple soil degradation indicators, and we found clear indications of degradation across multiple indicators. However, different indicators have different trajectories—pH and cation exchange capacity tend to decline linearly, and soil organic carbon and yields non-linearly. Future research should focus on how soil degradation in SSA leads to changes in ecosystem services, and how to manage these soils now and in the future.