Micro-macromorphological, physical, chemical and mineralogical investigations were conducted on irrigated and non-irrigated Podzolic soils from Petrolina, Pernambuco, Brazil. The aim of this study was to characterize and evaluate differentiation among soils, as a function of their position in the landscape, due to the combined effects of surface and subsurface relief as well as five years of sprinkle irrigation on mango trees. Data from four profiles were used, two from the irrigated area and two from a contiguous area of natural vegetation just recently cleared. The morphology and mineralogy of the soils were apparently not much affected by irrigation. Some morphological characteristics such as fragipans and mottles could be related to the movement and accumulation of water, as controlled by the surface and subsurface relief. Chemical modifications, especially salinity and sodicity levels, occurred in the lower horizons of soils from the non-irrigated area. These modifications are also controlled by the dynamics of water movement. Since the non-irrigated area was more affected than the irrigated area, the need to extrapolate the evaluation of irrigation impact beyond the irrigation project area was emphasized. Cementation and impermeability, observed in the deeper horizons, were attributed to the formation of micropans by illuvial clays.
salinization; sodicity; micropans