The profile distribution of FDA hydrolsis in paddy soils in Taihu region

The activities of fluorescein diacetate(FDA) hydrolysis and soil enzymes of 12 high fertility paddy soils located in Taihu region were analyzed in this paper.The activity of FDA hydrolysis in plowing layer was the highest and it decreased with soil depth.The activities of FDA hydrolysis were hardly detected in plowpan layer for some sampling soils.The enzyme activities of some soil sample sites shown apparently gradient decline.No any enzyme activity was detected at soil depth over 60 cm for all soils.There was significant difference of FDA hydrolysis activity among 12 soils.It ranged 50100 g/(gh) fluorescein with most concentrated into 6080 g/(gh) fluorescein.There was a highly significant correlation between the activity of FDA hydrolysis and the activities of acid phosphatase,urease,-glucosidase,dehydrogenase and arylsulfatase(P0.01) and a significant correlation with alkaline phosphatase(P0.05).The activity of FDA hydrolysis was positive correlation with the content of total N,total P,available N,available P and organic C in soils(P0.01) and a significant negative correlation with soil pH value.