Through profile morphology and physical analysis (texture, bulk and particle densities, pore size distribution, water storage and retention, and field capacity determined "in situ"), the behavior of a yellow Latosol located in Cruz das Almas (BA), Brazil, was studied when subjected to irrigation. The results made showed that the AB and BA horizons were hard (cohesion), mainly when dry, becoming a strong mechanic impediment fot root growth , aeration and water movement; due to the presence of the hard layer, the classic concept of field capacity was not applicable. Soil water contents in balance with potentials of -10 to -33 kPa and estimated in the laboratory using disturbed samples do not precisely represent the superior available water limit under field conditions. To calculate the available water range, water potential values were chosen in accordance to the horizons. Specific studies about the origin the observed cohesion, the choice of plants and agricultural machinery to break the physical barrier imposed by hard layers and improvement of soil drainage are recommended.
physical-hydric characteristics; cohesion