The study was conducted to exam the impacts of the vegetation types on soil nitrogen in Ziwuling secondary forest region loca ted in the middle part of the loess plateau.It was shown that the vegetation types could exert significant effects on soil total nitrogen according to the study results.The(0-5cm)total nitrogen contents of topsoilin the permanent grassla nd

bush land and forestland are 1.4～2.5 times of that in the farmland.The total nitrogen content of topsoil in the permanent grassland is almost similar to that in the forestland

which is higher than that in the bush land and restoring grassland.The total nitrogen contents of to psoil are much higher than that in the deep soil layers

and the soil total nitrogen contents decrease with the increase of soil depth in the profile in the grassland

bush land and forestland.Grass

bush and forest can raise the soil total nitrogen contents at the depth of 0-15cm

0-25cm and 0-50cm

respectively

indicating that soil nitrogen improvement depends on the vegetation types.The study results suggest that the soil total nitrogen can be significantly improved by conversing the farmland to grassland or forestland on the loess plateau.