Nitrification and nitrifying potential of tropical and subtropical soils

Summary Nitrification was measured in five different soils (slate alluvial soil, sandstone shale alluvial soil, sandstone shale and slate alluvial soil, red soil, and Taiwan clay). In these soils different lag periods were recorded before the onset of nitrification. Nitrifying activity was highest in sandstone shale alluvial soil and the lowest in acidic red soil. A part from those in the red soil, the numbers of nitrifying bacteria detected were all higher than numbers reported in temperate soils. However, there were no clear relationships between the numbers of nitrifying bacteria and the rate of nitrification in these soils. When soil cores were incubated for 3 weeks, no NO _inf2 ^sup- or NO _inf3 ^sup- was defected in the slate alluvial soil. This was ascribed to denitrification.