Nitrogen release characteristics of coated urea amended with biological inhibitors in meadow brown soil

Using a coated urea(Polyolefin-coated urea,70 day,POCU) made in Japan and a conventional granular urea as check,nitrogen release characteristics of four kinds urea amended with biological inhibitor and coated or coated by acrylic resin fertilizers in Meadow Brown Soil are examined under constant temperature incubating in laboratory.The result indicate that the maximum accumulative urea nitrogen released rate for four acrylic resin coated urea fertilizers was all observed after 48th day,up to 100% urea-N.The date for accumulative urea nitrogen released rates up to 80% was at 24th day and 28th day,respectively.The maximum of average release rates per unit time is 7.73%/d8.04%/d.The maximum of residue urea nitrogen in soil appears at 20 th day and 24 th day,respectively. The mixture of acrylic resin and NBPT cause a significant delay on urea release.