The study was conducted with brown soil(0-20 cm and 20-40 cm) in Shenyang agricultural university experimental station in order to research effecting mechanism of turnover,no-tillage,totary tillage on growth of maize's root.With pot experiment,it researched the impacts of different soil bulk density and sample from different soil layers on enzyme activities(polyphenol oxidase,catalase,acid phosphatase,urease,invertase).The results showed that the influence of different soil layers and different bulk density...