Application of fulvic acid-modified alginate in improving the utilization efficiency of secondary and trace element fertilizers.

This study synthesized a ternary polymer material composed of alginic acid, acrylic acid, and fulvic acid (AAF). Catalytic polymerization yielded a material that effectively binds calcium ions. AAF can bind up to 8.7 times its mass in calcium ions and has multifunctional agricultural applications. Experimental results showed that the optimal mass ratio of alginic acid, acrylic acid, and fulvic acid was 3:2:0.6. When the reaction was carried out at 60 °C for 6 h, the prepared material, containing a large number of carboxyl, hydroxyl, and other groups, exhibits extremely strong binding ability towards calcium ions. FTIR and X-ray diffraction confirmed the material's successful synthesis. Atomic force microscopy and energy-dispersive X-ray spectroscopy showed its calcium ion binding and inhibition of calcium salt precipitation. The sample's structure was simulated, and reaction mechanism and calcium-binding mode analyzed via DFT. AAF application significantly raised plant levels of iron, manganese, copper, zinc and calcium. Thus, AAF can inhibit calcium salt precipitation, boost phosphorus fertilizer efficiency, and slowly release metal ions. This increases the plant's absorption of metal ions, promotes plant growth, provides a new solution for the comprehensive promotion of water and fertilizer integration facilities and fertilizer efficiency enhancement in agricultural planting, and shows broad application prospects.