Soil Factors Influencing Percolation Test Performance

Abstract

AbstractThe variability of percolation test results is influenced by a complex association of soil and environmental characteristics. Statistical evaluation of 250 sites indicated considerable percolation test rate variation of individual tests within a single site. The variability of individual tests between sites on the same soil series was generally greater than the variability of individual tests within sites. The variation between sites on different soil series was even greater.The percent silt and coarse fragments of the subsoil were positively correlated with percolation rates, and percent clay and drainage class were negatively correlated. Factors not significantly correlated were bulk density, color value and percent sand in the subsoil, depth to bedrock, and depth classes. Variables, evaluated by analysis of variance, that showed significant relation to percolation rates were certain moist and wet subsoil consistence, grade of subsoil structure; subsoil texture, drainage classes, fragipans, parent material, slope class, and surface coarse fragments. Soil depth classes, color chromas and color values did not appear to be significantly related to percolation rates. The field designated permeability classes recorded during soil profile description, were generally lower than the determined percolation rates. Soil drainage classes were found to be closely related to percolation rates, with 82% of the moderately well, somewhat poorly, and poorly drained sites having rates slower than 2.5 cm/hour, and 76% of the 140 well‐drained sites having rates greater than 2.5 cm/hour.