Comparative performance of different urea coating materials for slow release--颗粒学报PARTICUOLOGY

Mohd Ibrahim, K. R., Eghbali Babadi, F., & Yunus, R. (2014). Comparative performance of different urea coating materials for slow release. Particuology, 17, 165–172. https://doi.org/10.1016/j.partic.2014.03.009

Comparative performance of different urea coating materials for slow release

Khairul Ridzwan Mohd Ibrahim ^a, Farahnaz Eghbali Babadi ^b, Robiah Yunus^a *

a Department of Chemical and Environmental Engineering, Faculty of Engineering, Universiti Putra Malaysia, Selangor 43400, Malaysia
b Institute of Advanced Technology, Universiti Putra Malaysia, Selangor 43400, Malaysia

10.1016/j.partic.2014.03.009

Volume 17, December 2014, Pages 165-172

Received 9 November 2013, Revised 22 February 2014, Accepted 2 March 2014, Available online 24 June 2014.

E-mail: robiah@eng.upm.edu.my

Highlights

• Four types of coating materials were investigated to coat urea granules.

• A gypsum-sulfur-based material was considered to best reduce dissolution rate of urea.

• Increasing the coating thickness increased considerably the crushing strength of coated granules.

• Sieving coating materials and adding wax led to an increase in efficiency of coated urea granules.

Abstract

Approximately 70% of the applied urea fertilizer may be lost into the environment. This loss is due to leaching, decomposition and ammonium volatilization in soil, water and air. Through coating, the slow release technology can be used to reduce losses and to increase the fertilizer efficiency. Sulfur has been used as a coating material, but the coating cracks easily because of its friability, sometimes being peeled off from the urea surface. In this study, four types of materials, namely, gypsum, cement, sulfur and zeolite, were mixed and used as coating materials to search for the most effective and cheap coating materials. The primary reasons for selecting these materials were improving fruit quality and preventing plant diseases, providing a plant nutrient, increasing soil fertility and water retention. The materials were also selected based on their availability, processiblity and price. The effects of the coating materials, thickness, drying time, sieving and sealant on the crushing strength and dissolution rate of urea were investigated. Coated urea with the same proportion of gypsum–sulfur exhibited high crushing strength and lower dissolution rate. However, the performance was further enhanced by applying molten paraffin wax on the hot urea surface. SEM images demonstrated that the micro-structure of gypsum–sulfur coated urea after sieving resulted in a smoother coated layer. The efficiency of the coated urea was improved by 26% using gypsum–sulfur (20% total coating), 3% paraffin wax and sieving the coating materials before application.

Graphical abstract

Keywords

Coating; Urea; Gypsum; Sulfur; Slow release; Crushing strength

文章导读