Vertical distribution of enzymes in soils under different land use systems

摘要

:Solum weighted average indicated that soil enzymes (urease, dehydrogenase and phosphatase) activity was more (3.3 mu g NH_4 formed g~(-1) soil hr~(-1), 70.8 mu g formazan formed g~(-1) soil hr~(-1) and 3.8 mu g p-nitro phenol formed g~(-1) soil hr~(-1) respectively) in the soil under mixed forest and less (0.8 mu g NH_4 formed g~(-1) soil hr~(-1) and 32 mug formazan formed g~(-1) soil hr~(-1) respectively) in the soil under tobacco land use systems with exception to phosphatase activity which was low (30.6 mu g formazan formed g~(-1) soil hr~(-1)) in the soil under current fallow land use system and was slightly lower than that of tobacco (32.0 mu g formazan formed g~(-1) soil hr~(-1)) land use system. Higher activity of soil enzymes in the soil under mixed forest land use system and lower activity of the same in the soil under tobacco land use system could be attributed to high and low organic matter content respectively. Slightly higher phosphatase activity in the soil under tobacco land use system than in the soil under current fallow land use system as indicated by solum weighted average might be due to high available phosphorus status in the soil under former land use system. However in surface horizon phosphatase activity was comparativelymore in the soil under current fallow than in the soil under tobacco land use systems and this might be due to high organic matter content in the soil under former land use system.