Abstract
Phosphorus (P) is vital for plant growth, but its agricultural use is limited by soil fixation and environmental loss. This study developed an organic ligand-responsive phosphate release system by hybridizing magnesium-iron-layered double hydroxides (Mg-Fe LDH) with pectin from apple and citrus (pectin-A/C). Structural properties and phosphate (PO(4)) release of LDH hybrids with different concentrations of metal precursors (0.5LDH-A/C, 2.5LDH-A/C) were evaluated. All hybrids exhibited higher PO(4) sorption than pristine Mg-Fe LDH, with 2.5LDH-A reaching 118.2 mg g(-1). Phosphate release kinetics showed that 0.5LDH-A/C provided slow release up to 1056 h, while 2.5LDH-A/C released 87.7% PO(4) with 4 mM citrate, responding to organic ligands. Synchrotron spectroscopy revealed that Fe substitution in LDH layers and Fe(III)-P species was the key influencing PO(4) release. The slow-release behavior of 0.5LDH-A/C and the ligand responsiveness of 2.5LDH-A/C highlight their potential to enhance sustainable agriculture by improving fertilizer efficiency, ensuring food security, and minimizing environmental impact.