Effects of Controlled Release Coated Urea on Soil Fertility and Enzyme Activities of Protected Vegetable Field

In order to investigate the relationship between soil enzyme activities and soil fertility with controlled release coated urea application,soil samples from protected vegetable field grown with cucumber,tomato and pepper were taken,and soil enzyme acitivities as well as nutrient content were determined.Results showed that application of coated urea significantly improved soil organic matter,total N,alkali soluble N,nitrate,ammonium,available potash,and decreased available P content in comparison to urea.Coated urea application increased the activities of polyphenol oxidase,phosphatase,and urease,which were significantly correlated with soil nutrient factors.However,coated urea application did not increased the activities of catalse and invertase, and no significant relationship was observed between catalse and invertase and soil nutrient factors.It is concluded that it is important to consider specific crop when studying the relationship between soil enzyme activities and soil nutrient.