Polymer coated slow/ controlled release granular fertilizers: Fundamentals and research trends

Synthetic fertilizers have supported the global world agriculture and food systems since 20th century, they have contributed significantly to increase soil productivity so as to achieve higher yields and ensure the world food security. However, excessive, and inappropriate use of mineral fertilizers combined with their fast dissolution nature, have shown major issues related to the environment and low nutrients use efficiency. Accordingly, it has become crucial to adopt modern technologies in order to manage nutrients supply for an optimum and effective use by the plants, while protecting the ecosystem from negative impacts. Polymer coating technology for fertilizers has shown the potential to better provide nutrients in a slow/ controlled rate for optimal crop nutrition with minimal environmental issues. In this review, we tried to establish a fundamental understanding of why and how polymer coated fertilizers (PCFs) are developed from the past to the recent trends. Telling the story of designing PCFs, we tried also to shed light on their function mechanisms as affected by many factors, their effects on the soil components, on the plant's growth and quality as well as on the environment and economic return. We aimed also in this review to deeply understand the interactions between the physicochemical properties of the polymeric coating, the fertilizer granules, the soil environment, and the crops through multidisciplinary investigation from polymer science, soil science and agronomy perspectives. Further considerations on the challenges and perspectives for future development of fertilizers with high nutrients use efficiency were discussed in this review.