Polyolefin Wax Modification Improved Characteristics of Nutrient Release from Biopolymer-Coated Phosphorus Fertilizers.

Coating fertilizer is an effective approach to increase the fertilizer use efficiency and reduce fertilizer application rate. However, only a few studies have focused on coating phosphorus (P) fertilizer, especially diammonium phosphate (DAP) due to its irregular shape and high specific surface area. A novel and low-cost strategy centered on wax-based surface modification and bio-based polymer coating was applied to improve the nutrient characteristics of coated DAP (CDAP). Regular DAP was modified with polyolefin wax and then coated with polyurethanes prepared from castor oil. Experimental results indicated that wax modification significantly decreased the specific surface area, angle of repose of DAP particles, increased the particle hardness, and then facilitated the formation of biopolymer-based coating. The CDAP from wax-modified DAP had better controlled-release performance compared with that from normal DAP. Findings from this study indicate that wax modification can be used as an effective technology to prepare highly efficient controlled-release P fertilizers.