ZHENG Wei-hong1，PAN Guo-xiang1，CHEN Jia2，XU Min-hong1，CHEN Hai-feng1, CAO Feng1，NI Sheng-liang1，TANG Pei-song1

(1. School of Life Science, Huzhou University, Huzhou 313000, China;
2. Deqing Dongxin Complex Fertilizer Science and Technology Co Ltd., Deqing 313201, China)

Abstract: A novel urea coated slow-release fertilizer was prepared by mixing urea with montmorillonite, diatomite and palygorskite, respectively. Subsequently, the synthesized complex was secondarily coated by ethylcellulose. The microstructure and morphology of the slow-release fertilizer was characterized by the means of several technologies such as XRD, IR, SEM, and others. A dynamic leaching experiment was used to study the slow-release properties of the coated fertilizer. The effect of the type of mineral, ratio of non-metallic mineral and urea, weight of secondary coating on the slow-release performance is discussed. Results demonstrate that the slow-release effect of urea slow-release fertilizer prepared by using palygorskite is better than with other non-metallic minerals. The slow-release property is better when the palygorskite/urea ratio is of 9:1 or 8:2. The initial rate of slow-release fertilizer prepared with palygorskite is lower than 20% within 24 h, and the cumulative release rate is lower than 80% over 28 days when the EC coating weight is 10%～12%, which is in line with national standards with respect to the technical index of slow-release fertilizer. XRD characterization shows that the palygorskite complex with the urea compound does not change the crystal phase structure of the palygorskite; the IR spectrum shows that there is a strong supramolecular role amongst palygorskite, urea and EC; SEM shows that the sample after coating is composed of dozens of micron-sized fibrous structures. The abundant micropores between fibres facilitates the slow-release property of urea. The outer EC membrane can form a layer to block losing of urea. Therefore, the coated urea slow-release fertilizer has the characteristics of slowly dissolving, long-term and nitrogen protection.

Keywords: non-metallic mineral; urea; ethylcellulose; coating; slow-release

Email: zhengwh@hutc.zj.cn

ACTA MINERALOGICA SINICA Vol. 36, No. 2, 2016, Page 247-252