The production cost of controlled-release fertilizers is an important factoring limiting their applications. To reduce the coating cost of diammonium phosphate (DAP) and improve its nutrition release characteristics, the fertilizer cores were modified by water polishing with three dosages at 1, 2, and 3%. The effects of modification were evaluated in terms of particle hardness, size distribution, angle of repose and specific surface area. Castor oil-based polyurethane was used as coating material for fertilizer performance evaluation. A pot experiment was conducted to verify the fertilizer efficiency of coated diammonium phosphate (CDAP) with maize. The results showed that polishing with 2% water reduced the angle of repose by 2.48–10.57% and specific surface area by 5.70–48.76%, making it more suitable for coating. The nutrient release period of CDAP was significantly prolonged by 5.36 times. Soil available phosphorous, enzyme activities, maize grain yield, and phosphorous use efficiency were all improved through the blending application of coated and normal phosphate fertilizer. This study demonstrated that water-based surface modification is a low-cost and effective method for improvement and promotion of controlled release P fertilizers.

控释肥料的生产成本是限制其应用的重要因素。为了降低磷酸二铵（DAP）的涂层成本并改善其营养释放特性，对肥料核心进行了水抛光，分别以1、2和3％的三种剂量进行了修饰。根据颗粒硬度，尺寸分布，休止角和比表面积评估了改性的效果。蓖麻油基聚氨酯用作评价肥料性能的涂料。进行盆栽试验以验证玉米包覆的磷酸氢二铵（CDAP）的肥料效率。结果表明，用2％的水抛光可将休止角降低2.48–10.57％，将比表面积降低5.70–48.76％，使其更适合于涂层。CDAP的养分释放期显着延长了5.36倍。通过包膜和普通磷肥的混合施用，土壤有效磷，酶活性，玉米籽粒产量和磷利用效率均得到改善。这项研究表明，水基表面改性是改良和推广控释磷肥的低成本有效方法。