New coating formulation for the slow release of urea using a mixture of gypsum and dolomitic limestone--颗粒学报PARTICUOLOGY

Eghbali Babadi, F., Yunus, R., Abdul Rashid, S., Mohd Salleh, M. A., & Ali, S. (2015). New coating formulation for the slow release of urea using a mixture of gypsum and dolomitic limestone. Particuology, 23, 62-67. https://doi.org/10.1016/j.partic.2014.12.011

New coating formulation for the slow release of urea using a mixture of gypsum and dolomitic limestone

Farahnaz Eghbali Babadi ^a, Robiah Yunus ^a *, Suraya Abdul Rashid ^b, Mohamad Amran Mohd Salleh ^b, Salmiaton Ali ^b

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

10.1016/j.partic.2014.12.011

Volume 23, December 2015, Pages 62-67

Received 26 September 2014, Revised 30 November 2014, Accepted 18 December 2014, Available online 25 April 2015, Version of Record 2 December 2015.

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

Highlights

• Urea coating using gypsum, sulfur and GML as coating materials and polyols as sealant was studied.

• Coating formulation of 50% gypsum and 50% GML and with 1.1% polyols was found to be optimum.

• The coated urea with optimal formulation could increase urea release resistance by 34.2%.

Abstract

The use of urea and urea-based fertilizers has increased considerably over the past 15 years. They currently account for approximately 51% of the world's agricultural nitrogen consumption. However, about 20–70% of the applied urea fertilizer is lost to the environment, causing serious pollution and increasing costs. These losses come from leaching, decomposition, and ammonium volatilization in the soil during handling and storage. Controlled release by coating can be used to increase urea fertilizer efficiency. We studied the use of gypsum, sulfur, and ground magnesium lime as cost-effective coating materials. All these coating materials contain nutrients required by plants. The effects of the coating composition and proportion of sealant on the rate of urea release and the crushing strength of the coated urea were investigated. We found that coated urea with the same proportion of gypsum–ground magnesium lime (GML) exhibited low urea release and high crushing strength. The performance was enhanced when using polyols as a sealant on the surface of the coated urea. A surface morphology analysis indicated a uniform and smooth surface on the coated film. The efficiency of the coated urea improved by 34.2% when using gypsum–GML (1:1 ratio) containing 1.1% polyols.

Graphical abstract

Keywords

Urea; Ground magnesium lime; Crushing strength; Rotary pan; Sealant; Polyol

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