Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 6/20/2005
Publication Date: 9/12/2005
Citation: Myers, D.B., Kitchen, N.R., Sudduth, K.A., Sadler, E.J. 2005. Landscape models of claypan soil profile properties as a function of divergence from clay-maximum depth [abstract]. Pedometrics 2005: Frontiers in pedometrics, International Union of Soil Scientists. p. 67.
Technical Abstract: Applications in spatial modeling of landscape geomorphology, crop growth, and hydrology need spatially continuous estimators of soil profile properties. Clay distribution in soil profiles of NRCS-Major Land Resource Area 113 of the Central Claypan Region exhibits genetic control on the distribution of other physical, chemical, and hydrologic soil properties of the profile. A prominent argillic horizon in these soils, known as the claypan, has a peak clay content of 45-65%, occurring just below its upper boundary. This study was conducted to develop predictive models of soil properties in claypan soil landscapes based on the depth of the profile-maximum clay content. Soil samples were taken from profiles distributed across a claypan landscape. Divergence from clay-maximum depth (DCMD) of a soil sample was calculated as its height above or below the depth of the maximum clay content for its source profile. Several soil properties including textural components, Ca, Mg, K, Na, Al, P, organic matter, buffer pH, and calculated PAWC and Ksat were modeled as both parametric and non-parametric functions of DCMD. Georeferenced bulk soil apparent electrical conductivity (ECa) measurements were used to spatially predict depth to clay-maximum. These predictions were, in turn, used to develop three-dimensional maps of soil property profiles in agricultural fields based on the DCMD functions. Divergence from clay-maximum depth effectively centered profiles from across claypan landscapes onto a single scale. Both parametric and non-parametric functions accurately modeled the DCMD profile of soil properties. Continuous three-dimensional representations of claypan soil landscapes suitable for crop and hydrology modeling were developed. The DCMD profiles of soil properties were useful for differentiating between surface alterations of soil properties and their genetic properties. These results establish that prominent genetic horizons which exhibit control on profile properties are useful as normalizing features for the spatial prediction of soil property profiles.