Variation of Soil Property Depth Functions.

Soil property depth functions are used to identify soil processes, locate discontinuities, and calculate nutrient stocks. We investigated whether the location of a vertical transect in a soil profile wall affects depth function type. In three soil profile walls, we sampled ten transects within the horizontal distance of 1 m. We used soil property data from each vertical transect to estimate soil property depth function types. We found that depth function types can vary considerably within the horizontal distance of 1 m in soil profile walls. In a Mollisol profile wall, three depth function types (minima-maxima, peak, and uniform) were identified for silt content. In an Entisol soil profile wall, three depth function types (gradational, minima-maxima, and peak) were identified for pH. This implies that variation of depth function type can be large, which has implications for soil pit sampling and interpretation.