The dynamics of soil N and K nutrition and of the activities of soil catalase

urease and polyphenol oxidase

and their relationships during wheat growth were studied. The content of soil available N

available K and non-exchangeable K changed regularly with wheat growth. The activities of soil CAT

URE

PPO increased previously

reached a maximum during the jointing and heading stage

then decreased and gradually remained stable.No relationships were observed between the content of soil AN

NEK and soil PPO activity

the content of soil NEK and soil URE activity during the early and late period of wheat growth

the content of soil AK and soil URE

PPO activities during the late period of wheat growth

while the relationships between the content of soil AN

AK

NEK and the activities of soil CAT

URE

PPO reached significant or extremely significant level during other periods of wheat growth.