Enhancing soil microenvironment, bean yield, nutritional quality and flavor of Coffea arabica through synergistic inorganic-organic fertilization in Southwest China

Improper fertilization in the longitudinal ridge valley area has led to soil degradation, negatively affecting coffee yield, quality, and flavor. A field experiment (2020–2022) with 5-year-old Coffea arabica (CIFC 7963) was conducted to develop a fertilization strategy that reduced pollution and recycled coffee husk waste. Two factors were tested: split-applied fertilizer (FR) and coffee husk organic fertilizer substitution (0.7FR+O). FR involved 750 kg ha⁻¹ inorganic fertilizer applied at four ratios during three reproductive stages, while 0.7FR+O replaced 30 % of the inorganic fertilizer with coffee husk organic fertilizer. The results showed increased fertilization during the berry expansion period resulted in higher soil microbial population, yield, and cup quality. Compared to FR, 0.7FR+O increased the soil nutrient composite index by 21.9–58.9 %, microbial population by 20.6–30.4 %, enzyme activity by 14.8–30.7 %, bean yield by 4.5–6.1 %, and nutritional quality by 8.7–32.0 %. FR and medium roasting revealed higher levels of pyrazines, pyrroles, and aldehyde in specific FR treatments, while deep roasting increased pyridines, pyrroles, and furans. The 0.7FR 5:7:3 +O achieved the highest cup quality score with 82. Correlation analysis showed significant relationships between soil microenvironmental factors and yield, quality, and flavor substances (Mental r > 0.5), with total sugar positively correlated with furans and pyrroles (Pearson r > 0.5). The multi-level fuzzy comprehensive evaluation identified 0.7FR 5:7:3 +O as the most effective strategy for improving soil conditions, bean yield, and nutritional quality. This study provides a theoretical basis for optimizing Coffea arabica fertilization practices in the longitudinal ridge valley area of southwest China, aiming to prevent soil compaction caused by excessive one-time fertilization and to address nutrient loss associated with the sole use of chemical fertilizers. • Split-applied fertilizer significantly increased the volatile compounds by 0.5–73.4 % in roasted beans. • Inorganic-organic fertilization boosted bean yield by 4.0–12.2 % and nutritional quality by 2.4–32.2 %. • The 0.7FR 5:7:3 +O fertilizer strategy effectively boosted Coffea arabica production.