Scaling nature-based solutions for soil restoration in Malawi through adoption dynamics and soil carbon recovery

Abstract Land degradation, declining soil fertility, and increasing climate variability threaten the sustainability of Malawi’s predominantly smallholder agricultural systems. Nature-based Solutions (NbS) offer a promising pathway for restoring soil health while enhancing climate resilience; however, integrated evidence linking adoption dynamics, biophysical outcomes, and institutional readiness remains limited. This study conducted a multi-zonal assessment across five agro-ecological zones in Malawi, operationalizing the IUCN Global Standard for NbS within a mixed-methods land-health monitoring framework. Household surveys (n = 89), laboratory analysis of 72 composite soil samples, key informant interviews, and policy review were combined with multivariate, hierarchical, and nonlinear modelling approaches. Overall NbS adoption was high (85.4%) but varied significantly across districts (χ² = 12.76, p = 0.026). Education (β = 0.47 ± 0.18, p = 0.011) and extension access (β = 0.53 ± 0.21, p = 0.008) were the strongest predictors of adoption, while farm size and gender were not significant. Hierarchical modelling revealed substantial district-level heterogeneity in both baseline adoption and extension effectiveness. Soil analyses indicated multidimensional degradation pathways characterized by organic carbon depletion (mean SOC = 0.82 ± 0.27%) and emerging sodicity (ESP > 15% in 18% of samples). Principal Component Analysis identified fertility-depletion and sodicity-stress gradients explaining 69.6% of total variance. Quantile regression demonstrated heterogeneous soil carbon responses to NbS, with stronger gains among higher-performing farms. Logistic growth modelling showed nonlinear SOC recovery trajectories, with rapid early gains followed by asymptotic stabilization near agronomic thresholds. Farmers reported high perceived effectiveness of NbS (mean = 4.3/5), with significantly higher ratings among women and more experienced farmers. Policy analysis revealed strong conceptual alignment with NbS principles but limited institutional coherence, financing, and multi-scale monitoring capacity. The findings indicate that NbS adoption in Malawi is behaviourally accepted and ecologically consequential but context-dependent. Scaling success will depend on geographically adaptive extension strategies, differentiated soil-restoration pathways, sustained domestic financing, and institutionalized multi-level monitoring systems. The integrated monitoring workflow presented here provides a transferable framework for strengthening evidence-based NbS implementation across sub-Saharan Africa.