EFFECT OF TOPOGRAPHY ON SELECTED SOIL PROPERTIES AND NITROGEN MINERALIZATION IN A DRY TROPICAL FOREST

Soil nutrients and nitrogen mineralization rates were measured along three topographic sequences in a seasonally dry tropical forest. Soil organic C, total N and P decreased downslope. Accumulation of soil organic C and N was related to the P content which, in turn, was controlled by the proportion of fine particles in the soil. Net N mineralization and nitrification rates ranged from 0 to 33-mu-g g-1 month-1 and 0 to 19-mu-g g-1 month-1, respectively, within the annual cycle and among the topographic positions. Annual mineralization increased from 125-mu-g g-1 dry soil at the hillbase to 203-mu-g g-1 dry soil at the hilltop. These differences in mineralization rates were obviously related to the distribution of substrate.