Effects of soil bulk density on N,P and K contents and phosphatase of soil from maize root

The method of backfilling soil was used to control soil bulk density in this test,thus the N,P and K contents as well as acid phosphatase and neutral phosphatase of soil with different bulk density from different soil layers of maize root were determined.The results showed that with the increasing of soil bulk density at 0~20 cm soil layer,the contents of N and K both increased,while the content of P decreased.At 20~60 cm soil layer,the contents of N,P and K all decreased with the increasing of soil bulk density.At 0~60 cm soil layer,the acid phosphatase decreased with the increasing of soil bulk density,while the neutral phosphatase increased.