Determinação da condutividade hidráulica em fluxo não saturado.

Abstract

"in situ" at four depths (15-30, 30-60, 60-90 and 90-120 cm) mm in the Latosol soil of the Experimental Station of the Center of Agricultural Sciences of UFPB, in Areia, Paraíba, using the methodology described by ROSE et alii (1965). Both the water content of the different depths and the matric suction were obtained under exclusive conditions of internal drainage. The results of this study revealed that, in a generalized manner, the K(Q) values ​​were low for all 4 depths. The highest values ​​corresponded to the depths of 15-30 and 90-120 cm, although they showed different behaviors, according to the water content of both extracts. In fact, at high water contents (0 > 0.31 cm 3 cm 3) the 90-120 cm layer presented higher K(0) values ​​than the 15-30 cm layer, while at low contents (Q < 0.31 cm 3 cm 3) it was the latter layer that showed a greater ability to transmit water under non-saturated conditions. These differences were attributed to structural variations, mainly those that determined, in turn, differences in the relative distribution of pore size. The lowest K(0) values ​​were presented by the third depth (60-90), closely followed by the 30-60 cm layer, which in the wet range (Q > 0.31 cm 3 cm 3) behaved quite similarly to the first (15-30 cm) and slightly exceeded the last depth (90-120 cm) in the driest zone (0 < 0.31 cm 3 cm 3). The differences between the 30-60 and 60-90 cm layers would be due, firstly, to structural variations, since they have very similar textural characteristics. Consequently, no decisive effect of the percentage distribution of the different particle sizes on the hydraulic conductivity K(Q) was observed, the values ​​of which were determined, fundamentally, by the structural properties of the different depths of the profile.