In the Low Plateaus of Pernambuco State, soils with subsurface compaction are found, which causes limitations in their use and consequently decreases agricultural productivity. With the objective to identify the occurrence of geological (lithological discontinuity) and/or pedogenetical processes involved in the genesis of this compaction, three representative soil profiles were chosen, distributed in a topographical sequence, located in the low plateaus in the municipality of Petrolina in semiarid zone of the State of Pernambuco - Brazil. Determination of granulometric distribution, sand fraction morphoscopy, sedimentologic parameters, density, porosity, calculation of sand and silt fractions free from clay and the relationships between fine sand, average sand, very fine sand/total sand and fine clay/total clay were studied. The results indicate that the subsurface compaction has not resulted from geological processes or due to lithological discontinuity, since the parameters studied did not present variations in depth, which indicates the occurrence of these processes.
low plateaus; hard soils; formation processes
