INTERRELATIONS AMONG PHYSICAL AND HYDRAULIC PARAMETERS OF NON-CRACKING SOILS

Water movement into soil is influenced by several soil hydraulic param eters that are often interrelated. In this study, data obtained for no n-cracking soils are examined for correlations and interrelations amon g the various parameters. Data on soil texture, bulk density, paramete rs of three selected infiltration equations (i.e. Kostiakov, Philip an d Horton equations), sorptivity and saturated hydraulic conductivity w ere obtained for a number of field sites in New South Wales, Australia . In addition, the published data on soil texture, bulk density and pa rameters of an infiltration equation (i.e. Kostiakov equation) for soi ls in Botswana were also included to extend the range of soil types an d field conditions in the present study. There was a very poor correla tion between the infiltration parameters of the Kostiakov equation and the soil physical properties such as bulk density and % of sand, silt and clay in the soil. The correlation between the steady-state infilt ration rate (b(r)) for a site measured with the ring infiltrometer and that (I-s) measured with the disc permeameter was high, but the value s of b(r) tended to be smaller than those of I-s. On the other hand, t here was a poor correlation between the sorptivity (S-r) measured for a site with the ring in filtrometer and that (S-d) measured with the d isc permeameter, and the values of S-r tended to be larger than those of S-d The hydraulic conductivity measured with the core permeameter s howed a poor correlation with similar parameters measured using other methods. Also, a high variability in infiltration characteristics was observed although the measurements were made only a few metres apart. (C) 1997 Silsoe Research Institute.