Abstract:

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.

Key words: coated emulsion, DAP, slow release performance, rate of release