Document Type : Research Paper

Authors

• Mahyar Ramezani Tazehabad ¹
• Elaheh Motamedi ²

¹ Department of Nanotechnology, Agricultural Biotechnology Research Institute of Iran (ABRII), Agricultural Research Education and Extension Organization (AREEO), Karaj, Iran

² Assistant Professor. Department of Nanotechnology, Agricultural Biotechnology Research Institute of Iran (ABRII), Agricultural Research Education and Extension Organization (AREEO), Karaj, Iran

Abstract

Objective: Urea is one of the most widely used fertilizers in agricultural practices; however, its high solubility in water leads to rapid leaching from the soil before plants can effectively absorb it. This issue results in significant fertilizer losses, increased agricultural costs, and various environmental concerns. A promising approach to address this challenge is the application of organic materials to coat urea granules, thereby slowing their dissolution rate in water. In this study, to mitigate fertilizer loss and enhance efficiency, carnauba wax (CW) was selected due to its biocompatibility and abundance. Additionally, urea granules were coated separately with CW combined with paraffin wax and stearic acid, polyethylene wax, and paraffin wax to evaluate the effectiveness of these materials in reducing urea dissolution.
Method: The method of dip-coating was employed as the primary technique for applying the coating onto the urea granules. To assess the release of urea over time, a specific quantity of the coated urea granules was carefully placed into 10 ml of distilled water, and the solution was monitored by collecting samples at predetermined time intervals. The concentration of urea released into the water at each interval was quantitatively determined using a UV-VIS spectrophotometer. Additionally, the diameters of the various coatings formed on the urea granules were examined and recorded on the seventh day of the experiment using a stereo microscope equipped with 40X magnification for precise measurements.
Results: The release of urea was monitored over a 41-day period, and the results revealed significant differences in the release rates based on the coating material used. Urea granules coated with carnauba wax exhibited the slowest release rate, with only 71.5% of the urea released by the end of the 41-day observation period. In contrast, granules coated with a mixture of carnauba wax and paraffin wax released their entire urea content into the water within just 7 days. Among the coatings tested, carnauba wax demonstrated the highest efficiency with a coating diameter of 0.504 mm, which also represented the smallest thickness compared to the other coating formulations.
Conclusions: The study results revealed that carnauba wax serves as an efficient coating material for urea granules, significantly prolonging their release time. This wax offers numerous benefits due to its natural origin, biocompatibility, biodegradability, and non-toxic properties. Its application enhances sustainability while ensuring safety, making it a highly suitable choice for controlled-release purposes in agricultural or similar settings. These findings highlight its potential to revolutionize fertilizer usage, reducing environmental impact and improving cost efficiency.

Keywords

• Biocompatible
• Carnauba wax
• Dip-coating
• Nitrogen fertilizer
• Polyethylene wax