Flow‐Made Fertilisers for Cherry Belle Radish ( <i>Raphanus sativus</i> L.) Growth in Acidic and Calcareous Soils

ABSTRACT Phosphorus (P) availability is strongly constrained in both acidic and calcareous soils due to fixation reactions, reducing nutrient‐use efficiency and driving excessive fertiliser inputs. This study develops and evaluates a series of chitosan–apatite–citrate ( CAC) fertilisers prepared using four continuous‐flow manufacturing strategies: a coiled‐flow inverter ( CFI_CAC ), a water/oil sheath‐flow system ( Sheath_CAC ), a Stolichem scalable agitated baffle reactor ( Stoli_CAC ), and a pilot‐scale spray dryer ( Spray_CAC ). All fertilisers were characterised for composition (phosphate, citrate, chitosan) and microstructure, and their phosphorus releasing behaviours in water were quantified. Distinct release behaviours were observed, which were impacted via citrate content, particle morphology, and the presence of a chitosan hydrogel shell. The Sheath_CAC formulation exhibited the most suitable release profile in aqueous solutions according to the chosen logistic growth model for releasing behaviour ( R 2 = 0.97 ) due to its defined capsule architecture. Radish growth experiments were conducted over two consecutive model seasons in acidic and calcareous soils to assess the functional performance of the materials. In the context of this study, Sheath_CAC consistently produced the high germination rate, leaf development, biomass accumulation, and P uptake across both soils. In acidic soil, Sheath_CAC increased dried root yield by up to 60% and total P uptake by 46.9% compared with the control, while maintaining moderate soil P levels, indicating reduced susceptibility to leaching compared with commercial soluble fertiliser. In calcareous soil, Sheath_CAC partially mitigated P fixation effects, sustaining higher biomass and P uptake relative to the untreated control. While commercial fertiliser maintained the highest available P levels, Sheath_CAC demonstrated stable and controlled release which boosts the yield of radish. These findings highlight Sheath_CAC as a high‐performance fertiliser balancing steady P availability with sustained plant growth.