Flow-Made Fertilisers for Cherry Belle Radish (Raphanus Sativus L.) Growth in Acidic and Calcareous Soils

Abstract

Phosphorus (P) availability is crucial for plant growth, yet conventional fertilisers suffer from excessive leaching and low nutrient use efficiency. Slow-controlled release P fertilisers, particularly chitosan-based formulations, offer a solution by reducing nutrient loss while ensuring sustained P supply. However, most next-generation fertilisers are produced in batch processes, limiting scalability. This study addresses this challenge by employing continuous flow technologies to develop chitosan-apatite-citrate (CAC) fertilisers for controlled P release and soil remediation. Their performance was evaluated using radish as a demonstrator crop. Growth rate, biomass yield, and P distribution across two model growing seasons were evaluated. The core-shell CAC fertiliser, prepared by utilising crosslinking reaction in a sheath flow of water/oil system (Sheath_CAC), consistently outperformed other treatments, exhibiting the highest sprouting rate and fastest early growth in both seasons. Compared with the control pots, the Sheath_CAC promotes the highest dried root yield (increase of 39% in season one, and 60% in season two), surpassing the commercial fertiliser (1% in season one, and 60% in season two); P uptake of radish treated with Sheath_CAC increased by a maximum of 46.9%. P content in biomass declined due to greater biomass accumulation, total P uptake remained stable, indicating efficient nutrient utilisation. While commercial fertiliser maintained the highest available P levels, Sheath_CAC demonstrated stable, controlled release, minimising leaching risk. These findings highlight Sheath_CAC as a high-performance fertiliser balancing steady P availability with sustained plant growth. This study underscores the potential of flow-manufactured controlled-release formulations in enhancing nutrient efficiency and reducing phosphorus loss.

Keywords: Flow chemistry, controlled release fertiliser, soil remediation, crop yield enhancement