Measurement of sated hydraulic conductivity of surface soil in the field with a small-plot sprinkling infiltrometer,

The purpose of this study was to determine the sated (near-saturated) hydraulic conductivity, K, of surface soil in the field. With K as a parameter, an equation describing cumulative water runoff from a small-plot sprinkling infiltrometer was developed from an empirical infiltration equation matched to Green–Ampt infiltration theory for constant-intensity water application; also incorporated was a fixed-average static concept of surface water storage on the small soil plot. To evaluate K, this runoff equation was fitted by least squares to field data from a small-plot (1.16 m×1.16 m) sprinkling infiltrometer on four combinations of soil type and cover: Clermont and Cincinnati silt loam (grass), and Chelsea sandy loam (grass and fiberglass). The runoff equation fitted the field data very well, especially at times greater than 10–15 min after the first appearance of water runoff. The order of the mean K values for the four soils-cover combinations was: Chelsea-grass>Chelsea-fiberglass>Cincinnati-grass> Clermont-grass, which is compatible with the physical characteristics of these soils and covers. Of the various differences between mean K values, half were statistically significant. The fixed-average static surface-water storage behaved in reasonable fashion, both physically and statistically, and in regard to site slope and plot cover.