Epsilon Open Archive

Abstract

The tension infiltrometer is a device for measuring unsaturated hydraulic conductivity [KC'!')] in the larger soil pores. By regulating the supply pressure head during infiltration with the help of a bubble tower, it is possible to control the size range of soil pores that transmit water. This technique was used in the characterization of infiltration in two rainfed hillsides (north and south exposure) of the central zone of Chile. The results showed smaller K(Ψ) values for the north exposure, with accentuated differences close to saturation (zero pressure head). These differences may have been attributed to differences in texture and organic matter contents observed for the two exposures. Furthermore, K(Ψ) presented a tendency to increase with increasing slope. This tendency, observed also in complementary laboratory works was to a part explained by the deviation from requirements of measurements on level ground. A way of adjusting for slope influence is proposed. In the field study, after adjustment, the differences in K(Ψ) were attributed to the differences in the vertical and lateral hydraulic conductivity and to the development of surface sealing occurring in low slope plots. Finally, a stepwise regression analysis showed that K(Ψ) parameters were explained by the slope of the hillside and the proportion of textural separates in the soil surface.