Mechanism of improved phosphate uptake efficiency in banana seedlings on acidic soils using fertigation

Fertigation improves nutrient uptake efficiency greatly, while the mechanism of increased nutrient uptake efficiency remains unclear. In this study, the effects of conventional phosphate (P) fertilization (by mixing fertilizer with soils) and fertigation (by dissolving fertilizer in water) on P uptake were compared in banana (Musa sapientum) seedlings. Results indicated that, compared with conventional fertilization, fertigation increased the concentration of available P by 108% and decreased the P sorption index by 31% in the 0–8 cm surface soil of banana roots. Fertigation enhanced the transformation of different P fractions, increased the concentrations of aluminum-bound P (Al–P), iron-bound P (Fe–P) and occluded-P (O-P), and decreased the pH value by 0.3 units. However fertigation did not influence the activity of acid phosphatase, but increased microbial biomass and root activity by 25.5–67.8%. Furthermore, fertigation increased the root distribution in the 0–8 cm soil layer by 7.8–9.4% compared with conventional fertilization. These results suggest that fertigation increases P uptake efficiency as the result of increased root activity, root distribution, microbial biomass and reduced P sorption index in the surface soil of banana seedlings.