Layered hydroxy double salts of copper and zinc intercalated with borate: Synthesis, characterization, and potential agricultural applications

Copper (Cu), zinc (Zn), and boron (B) are essential micronutrients for plants, and slight variations in their soil contents can cause deficiencies or toxicity, compromising productivity and food quality. Developing new fertilizer formulations that efficiently supply nutrients, minimize losses, and enhance availability is crucial for sustainable agriculture. Layered hydroxy double salts (HDSs) offer a promising alternative as slow-release fertilizers, reducing leaching and plant toxicity, while increasing plant uptake. This study aims to synthesize and characterize a Cu and Zn HDS intercalated with borate anions (CuZn-BO 3 -HDS), analyze its dynamics in the soil regarding nutrient release and leaching potential, and evaluate it as an alternative fertilizer compared to conventional sources. The synthesized materials were characterized using X-ray diffraction, Fourier-transform infrared molecular absorption spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, specific surface area, and elemental chemical analysis. A laboratory release study was conducted using both soluble and insoluble sources of each micronutrient. A soil column leaching study and a greenhouse experiment with successive crops was performed with a sandy soil. The chemical characterization confirmed the efficiency of the synthesis method, producing a material suitable for slow-release fertilization with good crystallinity and morphology. Release and leaching studies demonstrated that CuZn-BO 3 -HDS exhibited slow release and minimal leaching, indicating its potential as a highly efficient fertilizer. The agronomic performance indicated that nutrients from CuZn-BO 3 -HDS were gradually absorbed by maize and sunflower without causing toxicity, resulting in higher Cu content in plant tissue. Therefore, CuZn-BO 3 -HDS is a promising material for sustained nutrient release in sandy soils, effectively providing nutrients, reducing leaching losses, and minimizing the need for frequent applications of conventional fertilizers. • This pioneering study successfully synthesized the layered hydroxy double salts. • The application of layered hydroxy double salt in agronomic field remains unexplored. • Performance of the Cu and Zn layered hydroxy double salt intercalated with borate. • The layered hydroxy double salt demonstrated a slow release of Cu, Zn, and B. • The CuZn-BO 3 -HDS proves to be a promising slow-release fertilizer for plant growth.