The soil quality may have an influence in incidence of trunk phloem necrosis (TPN), which is the currently one of economically important disease of H. brasiliensis. This study aims to define the impact of TPN on soil biological activities and to investigate the impact of different soil management practices on soil functions. Principal component analysis showing associations between healthy and TPN trees, and soil enzyme activities revealed that polysaccharidases were lower under soil affected by TPN whereas N- glucosaminidase was higher. Termite density was associated with soil under TPN areas. The method of culturable-dependant was used in order to analyze fungal populations. Although fungal density in soil under trees affected by TPN was not significantly different from soil under healthy trees, some fungi were abundant only in soil with TPN. The similarity dendrogram of fungal 28S rDNA revealed that soil fungal community in healthy tree zones was different from TPN tree zones. Soil biological activities in soils with different managements including without external organic input, external organic input and Pueraria cover crop + external organic input were investigated in order to find out the proper soil management for H. brasiliensis. PCA revealed that most enzyme activites were low in soil without organic management. Xylanase activity was the highest in soil with Pueraria whereas the highest FDA hydrolysis activity was asscociated with soil under external organic input. Macrofauna density was also the lowest in soil without organic amendment.
