• Multi-site (3 regions), 4-year field validation in HLB-affected citrus. • AMF colonization increased to >60% under integrated amendment. • Microbial biomass and soil CEC significantly improved (p ≤ 0. 05) • CLas titer reduced by 37% with corresponding symptom suppression. • Yield increased by 28–35% with improved TSS/TA ratio. Huanglongbing (HLB), associated with Candidatus Liberibacter asiaticus (CLas), severely constrains citrus production in calcareous, stress-prone soils. This four-year, multi-site field study (2021–2024) evaluated a multi-component soil amendment integrating biochar, arbuscular mycorrhizal fungi (AMF), plant growth-promoting rhizobacteria (PGPR), chitosan, calcium-magnesium nitrates, fulvic acid, and brassinosteroids. The fully integrated treatment (T 6) significantly (p ≤ 0. 05) improved soil organic carbon (172%), cation exchange capacity (67%), and AMF colonization (>60%) compared with the untreated control. CLas titer decreased from 6. 2 to 3. 9 log copies g −1 leaf tissue (absolute reduction of 2. 3 log copies; ≈37% reduction), accompanied by reductions in disease severity indices (>55%). Root length density increased by 85% and fine-root biomass by 98%, while necrosis declined. Photosynthetic rate, leaf nutrient status, and relative water content improved significantly. Total yield increased by 67% (from 52. 4 to 87. 6 kg tree −1), and fruit quality (total soluble solids/titratable acidity ratio) improved from 8. 5 to 13. 8. Economic analysis indicated that despite higher input costs (1, 850 ha −1), T 6 generated the highest net return (8, 410 ha −1) with a benefit-cost ratio of 5. 54, demonstrating economic feasibility for large-scale adoption. Although CLas was not eliminated, integrated soil biological management was associated with pathogen suppression and enhanced orchard resilience. These findings support soil-centered biological integration as a complementary strategy for managing HLB-affected citrus systems
Tadayon et al. (Wed,) studied this question.