It is one of the effective measures to use installing cultivation for culturing vegetables at present.However,owing to successive cropping in the special ecological environment,i.e.,in greenhouse and plastic shed,an obstacle would be produced in the soils,gradually resulting in a decrease in crop yield.The obstacle was investigated through dealing with nitrification and denitrification.The results show that there were stronger nitrifying activities in soils under greenhouse and plastic bed conditions,and he...