A Systematic Review of Soil Health Restoration Pathways and Ecosystem Functionality in Bhutan’s Mountain Agro-ecosystems

Abstract

This systematic narrative review evaluated soil health restoration pathways in Bhutan using evidence synthesized from peer-reviewed literature, national datasets, and technical reports. The review examined interventions across five domains: soil regeneration, nutrient cycling, crop diversification, hydrological resilience, and ecological pest regulation within farming systems characterized by steep slopes, fragmented landholdings, and annual soil losses ranging from 3–21 t ha⁻¹. Findings showed that integrated soil and nutrient restoration practices comprising organic amendments, residue retention, reduced tillage, and diversified cropping systems substantially improved soil quality and ecosystem stability. Regenerative management increased soil organic carbon by approximately 17%, with sequestration rates ranging from 0.2–1.5 Mg C ha⁻¹ yr⁻¹ depending on management intensity and site conditions. Organically managed systems recorded higher total nitrogen (0.38%) and cation exchange capacity (22.26) compared to conventional systems (0.26% and 19.45, respectively). Between 2005 and 2023, sustainable land management initiatives established 1,347.42 ha of terracing, 2,097.02 ha of contour hedgerows, 355.17 ha of stone bunding, and 3,333.48 ha of landslide stabilization plantations, significantly contributing to erosion control and landscape restoration. However, labour shortages, limited mechanization, and weak market integration continue to constrain widespread adoption of regenerative practices in Bhutan.