Tuesday, November 14, 2006 - 9:45 AM

A Quantitative Pedology Approach to Continuous Soil Landscape Models.

D. Brenton Myers1, N. R. Kitchen2, K. A. Sudduth2, B. D. Mayhan3, R. J. Miles1, and E. J. Sadler2. (1) Univ of Missouri, 269 Ag Engineering Bldg, Columbia, MO 65211, (2) USDA-ARS, Cropping Systems and Water Quality Research, 269 Ag Engineering Bldg, Columbia, MO 65211, (3) Center for Agricultural, Resource and Env Systems, 130 Mumford Hall, Univ of Missouri, Columbia, MO 65211

Continuous representations of soil profiles and landscapes are needed to provide input into process based models and to move beyond the categorical paradigm of horizons and map-units. Continuous models of soil landscapes should be driven by the factors and processes of the soil genetic model. Parametric soil depth functions can be combined with spatial pedogenic factor data (e.g. ClOrPT) to map soil profile properties across the landscape. Loess-derived soils in upland landscapes of Northern Missouri provided a case study for this investigation. A large database of horizon-sampled soil profile data was converted to continuous pedometric depth functions which handle the vertical anisotropy of pedogenesis. This was achieved via a clay-maximum depth estimation procedure, and coherent depth translation. The transformed soil profile data was fitted to peak and rational functions having parameters that reflect specific features of the soil property distribution curve such as peak amplitude, amplitude location, skew, attack, and decay. The parameters of these pedometric functions are analogous to the soil property maximum, depth to maximum, abruptness, and profile anisotropy. The function parameters were then predicted across regional soil landscapes, using spatial genetic factor data such as climate and paleoclimate information, loess thickness, and digital elevation models. These continuous models of soil landscapes are important for applications where the soil map-unit scale is insufficient, such as in precision agriculture, high-resolution hydrology and plant modeling, and intensive land-use planning.