Productivity and quality of banana in response to chemical fertilizer reduction with bio-organic fertilizer: Insight into soil properties and microbial ecology

Understanding the responses of ecosystem functions and services (e.g., fruit productivity, carbon sequestration, and nutrient cycling) to fertilization practices and exploring the underpinning mechanisms are essential to achieve sustainable development in the banana industry. Here, a field plot experiment was conducted to explore the effects of partially substituting chemical fertilizers with different application rates of bio-organic fertilizer (BIO) and organic fertilizer (OF) in banana (Musa acuminata L. cv. ‘Baodao’) production. Accordingly, 7.65 t ha^–1 of BIO and OF was used for a field demonstration experiment to verify prior experimental results and explore the shifts in soil microbial ecology. The results showed that the greatest banana productivity was achieved at 81.6 t ha^–1 following BIO application. The reducing sugar contents, vitamin C contents, and sugar-to-acidity ratios of banana fruit following BIO application were higher than those of the control with chemical fertilizers alone, and a similar trend was observed for soil pH values, organic matter contents, available nutrients contents, and cation exchange capacity. BIO was superior to OF in improving soil microbial biomass, but their effects on the number of cultivable microbial populations were opposite. The application of BIO increased Chloroflexi and Basidiomycota abundances, while decreasing Acidobacteria and Ascomycota abundances. Acidothermus, Bradyrhizobium, Bryobacter, Mortierella, and Moesziomyces were enriched following BIO application. Linear discriminant analysis effect size identified 20 differentially abundant taxa between treatments. Variation partitioning analysis revealed that soil properties, fertilizer type, and their interaction accounted for 93.0% of the variation in banana productivity and quality. Banana productivity and quality as well as the majority of soil properties varied significantly with fertilizer application rate. Bacterial functional genes associated with carbohydrate metabolism, lipid metabolism, and biosynthesis of other secondary metabolites were upregulated by BIO application. Overall, appropriate application of BIO combined with chemical fertilizers improved soil properties and reshaped bacterial and fungal ecology, thus improving banana productivity and quality. Our results indicated that partial substitution of chemical fertilizers with BIO is a promising fertilization practice for banana production in acid soil ecosystems.