Current Research on Geography, Earth Science and Environment Vol. 10

Soil health has become a central justification for organic farming, yet the strength of that justification varies considerably across soil functions, spatial scales and accounting conventions. This critical narrative review examines what the accessible evidence supports about the effects of certified organic and closely related low-external-input management on soil chemical, biological and physical condition, and where the literature remains inconsistent or methodologically constrained. Literature was identified through open scholarly indexes and citation tracking, with the final search conducted on 2 July 2026, and appraised for design adequacy, system-boundary treatment, sampling protocol and analytical transparency rather than aggregated quantitatively. The evidence is strongest and most internally consistent for soil biological indicators: microbial biomass, enzyme activity, mycorrhizal colonisation and earthworm populations are repeatedly higher under organic management across climates and crop types, and community composition shifts in ways that plausibly support nutrient mineralisation and disease suppression. Soil organic carbon differences are consistently positive but considerably more fragile, because the largest reported gains depend on imported organic matter whose production carries an off-site carbon cost, and because effect sizes contract sharply when analyses are restricted to systems without net external inputs. Physical benefits are real but selective, appearing chiefly in aggregate stability, infiltration and plant-available water, while compaction indicators respond weakly and are strongly confounded by tillage intensity. Three problems limit confidence across the field: the treatment of organic farming as a single undifferentiated intervention rather than a bundle of separable practices; the inconsistent handling of sampling depth, bulk density and system boundaries; and a marked geographical concentration of evidence in temperate Europe and North America. The soil health advantages of organic management are best interpreted as practice-specific and context-dependent rather than as intrinsic properties of certification, and the practices that generate them are transferable to non-certified systems.