以玉米淀粉、聚乙烯醇、二氧化硅（湿法磷酸脱氟制备氟化钾时的副产物）、丙三醇和膨润土为主要原料,以水作为溶剂制备包膜乳液,以高压喷枪将包膜乳液多次雾化对磷酸二铵颗粒（DAP）进行喷涂,成功制备了一种磷酸二铵缓释肥。研究了不同金属离子种类、不同离子浓度对其缓释性的影响;金属离子种类对土壤持水性能的影响;包膜肥料对土壤保水性和持水性能的影响。结果表明：磷酸二铵包膜肥料的缓释性能随金属离子浓度的增加而增加,多价金属阳离子对包膜肥料缓释性能的影响大于单价金属阳离子;土壤的持水性能会受金属离子种类的影响;包膜肥料能提高土壤的保水性能和持水性能。

Taking by-product silica which is from the preparation of potassium fluoride bydefluorination of wet-process phosp-horic acid,corn starch,polyvinyl alcohol,glycerol,bentonite as main materials and water as solvent,the coated emulsion was obtained.Then the atomizing coated emulsion by high pressure spray guns several times on DAP grain was sprayed and a DAP slow release fertilizer was successfully synthesized.The effects of different metal ions and ion concentration on the slow release feature of the fertilizer were studied.The effects of metal ion species on soil water holding performance was studied. The effects of coated fertilizers on soil water retention and water holding performance was also researched.The results showed that the slow release feature of DAP coated fertilizer increased along with the ion concentration,and the effect of polyvalent metal cation on the slow release feature of coated fertilizer was greater than that of monovalent metal cation.Soil water holding performance was affected by metal ion species.It was also found that the coated fertilizer could improve the water retention and water holding performance of soil.