Recently, the Fertilizer and Fertilization Technology Innovation Team at the Institute of Agricultural Resources and Regional Planning (IARRP, part of the Chinese Academy of Agricultural Sciences) successfully developed a nano-SiO2-modified superhydrophobic polyurethane-coated controlled-release urea. This innovation addresses a key industry challenge: the poor hydrophobicity of polyurethane coating layers, which often results in a shortened nutrient release duration. This novel fertilizer achieves a water contact angle (WCA) of 165.44°, with a controlled-release period lasting up to 61 days. The research findings have been published in ACS Omega (IF 4.3).

Controlled-release fertilizers constitute a foundational technology for advancing precision nutrient management in modern agriculture. Through precise modulation of both the release kinetics and temporal profile of nutrients, these systems enable dynamic synchronization with crop-specific nutrient uptake trajectories across phenological stages. When deployed under single-application regimes, they substantially reduce nitrogen losses via leaching, volatilization, and denitrification—thereby safeguarding yield stability and maximizing grain or biomass output—while simultaneously enhancing field-scale nitrogen use efficiency (NUE), lowering labor inputs per unit area, and generating synergistic environmental and economic returns. However, in practical applications, polyurethane-coated fertilizers generally suffer from insufficient hydrophobicity and relatively short nutrient release durations, making it difficult to precisely match nutrient demand throughout the entire crop growth cycle. These limitations have hindered their large-scale adoption. Therefore, integrating nanotechnology with coating-based controlled-release technologies to extend nutrient release duration and achieve precise nutrient regulation has become a key direction for technological breakthroughs in this field. Nano-SiO₂, characterized by its wide availability, low cost, high chemical stability, good biocompatibility, low toxicity, large specific surface area, and strong surface adsorption and reactivity, has emerged as an optimal modification material to enhance coating hydrophobicity.

In this study, different sizes of SiO2 particles were used as core materials. First, 1H,1H,2H,2H-perfluorodecyltrimethoxysilane (FAS) was covalentlygrafted onto the surface of SiO2 via a two-step method of alcoholysis followed by condensation, effectively improving the dispersion of SiO2 and successfully producing FAS-SiO2-modified superhydrophobic materials. Subsequently, the effects of three preparation methods—surface coating, blending, and outer-layer blending—on coating surface energy, microstructure, roughness, water contact angle, and fertilizer release duration were systematically investigated. The results indicate that the surface coating method maximizes the superhydrophobic properties of FAS-SiO2, significantly reduces coating surface energy, and constructs a stable micro/nano-scale superhydrophobic structure. The resulting coating achieved a water contact angle of up to 158.24°and exhibited excellent stability, successfully addressing the key technical issue of nanoparticle coating detachment.

Further analysis revealed that the particle size of FAS-SiO2 significantly influences coating performance and nutrient release duration. Among the tested variants, polyurethane-coated fertilizer modified with 20 nm FAS-SiO2 demonstrated the best overall performance, extending the controlled-release period by 21 days compared with conventional polyurethane-coated urea. This research not only provides solid theoretical support for the development and application of nano-enabled controlled-release fertilizers, but also offers important technical guidance for accelerating industrial upgrading and product iteration in coated fertilizer technologies, thereby contributing to the green and efficient development of modern agriculture.

Zhao Sen, a master's student at the Institute of Agricultural Resources and Regional Planning, CAAS, is the first author of the paper, while researchers Li Juan and Yang Xiangdong serve as co-corresponding authors. This research was jointly supported by the National Key Laboratory for Efficient Utilization of Arid and Semi-Arid Cropland in Northern China, the National Key R&D Program during the 14th Five-Year Plan (2024YFD1700102), the National Natural Science Foundation of China (32372819), and the Fundamental Research Funds for Central Public Welfare Scientific Research Institutes (1610132023005).

Figure. Schematic diagram of the preparation mechanism of nano-SiO2-modified superhydrophobic polyurethane-coated controlled-release fertilizer.

Citation and original link

Zhao S, Gu D R, Yang X D, Li J, 2026. An in-depth study on the enhanced controlled-release performance of coated urea via the construction of a multiscale SiO₂-based superhydrophobic coating. ACS Omega, 11(10): 16612–16624. DOI: 10.1021/acsomega.5c12866.

Original link: https://pubs.acs.org/doi/10.1021/acsomega.5c12866