The Innovation Team of Fertilizer and Fertilization Technology at the Institute of Agricultural Resources and Regional Planning (IARRP) of the Chinese Academy of Agricultural Sciences (CAAS)  has recently achieved a significant breakthrough by creating a novel ethyl cellulose-coated controlled-release urea. This innovative fertilizer boasts a remarkable controlled-release performance lasting approximately two months. By using ethyl cellulose as the coating material, the team successfully overcame membrane brittleness through material modification, resolving structural defects by optimizing process conditions, and significantly enhancing the controlled-release performance through surface treatment. This development provides a solution to the degradation challenges of polymer-coated controlled-release materials. The related research findings have been published in the journal Carbohydrate Polymer Technologies and Applications. 

Under single-application conditions, controlled-release fertilizers can synchronize nutrient supply with plant nutrient uptake, thereby ensuring crop yield, minimizing nitrogen loss, and optimizing nitrogen management in farmland. This synchronization ultimately aligns environmental sustainability with economic efficiency.  However, the development of polymer-coated fertilizers has been constrained by challenges such as the difficulty in degrading the coating material. Therefore, using natural biomaterials as coating materials for controlled-release fertilizers is a key technological focus for future advancements. Ethyl cellulose, an ether derivative of natural cellulose, exhibits excellent hydrophobicity and biodegradability; however, it presents challenges such as membrane brittleness and difficulty in achieving a uniform coating. Previous studies on ethyl cellulose-coated urea have frequently reported problems with non-uniform membrane structure and suboptimal controlled-release performance. 

This study initially optimized the spray phase inversion method for preparing coated urea, identifying the temperature of the fluidizing gas as the primary factor influencing membrane integrity. By maintaining the coating temperature at 50°C, a continuous, uniform, and dense membrane was successfully formed, resulting in optimal controlled-release performance. The feed rate and concentration of the coating solution were determined  to be secondary influencing factors. Moreover, the incorporation of dibutyl sebacate for membrane modification enhanced its mechanical properties, increasing the elongation at break by 0.5%-2%. Surface treatment with paraffin further improved the membrane's hydrophobicity, raising the water contact angle from 100° to 130°, and extending the controlled-release duration to 50 days, thereby meeting the requirements of the ISO 18644:2016 standard. This research offers a feasible technical approach for the development and application of biodegradable materials in the field of controlled-release fertilizers, contributing to industrial upgrading and product innovation in coated fertilizer technology.

Zhou Yuanfang, a master's student at the IARRP, is the first author of the paper, with researchers Yang Xiangdong and Li Juan serving as co-corresponding authors. This study was supported by the National Key Laboratory for Efficient Utilization of Arid and Semi-Arid Cultivated Land in Northern China, the National Key R&D Program of China (2022YFD1700601), and the Fundamental Research Funds for Central Non-profit Scientific Institution  (No. 1610132023005).

Illustration of Ethyl Cellulose-Coated Controlled-Release Urea Preparation

Citation and Original Link:

Zhou, Y. F, Li, H., Zhao, S., Yan, S., Li, J., & Yang, X. D. (2025). Optimization of Ethyl Cellulose-Coated Urea for High-Performance Controlled Release. Carbohydrate Polymer Technologies and Applications, 100920.

Original link: 

https://doi.org/10.1016/j.carpta.2025.100920.