Submitted to: Soil Science Society of America Journal
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/20/1999
Publication Date: 2/1/2000
Citation: SHAW, J.N., WEST, L.T., RADCLIFFE, D.E., BOSCH, D.D. PREFERENTIAL FLOW AND PEDOTRANSFER FUNCTIONS FOR TRANSPORT PROPERTIES IN SANDY KANDIUDULTS. SOIL SCIENCE SOCIETY OF AMERICA JOURNAL. 64(2):670-678. 2000. Interpretive Summary: Computer models that predict the flow of water and the transport of chemicals through the environment provide critical insight for managing our natural resources. This management in turn helps us minimize the impact we have on the environment. The computer models require accurate estimates of physical characteristics of the environment or parameters. A laboratory study using large soil columns was conducted to evaluate these parameters. The flow of water and transport of chemicals through the columns were measured. Parameters that described this flow and transport process were then determined so that a computer model could accurately predict the observed data. These parameters can be used to model natural systems and to examine alternative agricultural management schemes. Studies such as this are critical to developing parameter sets for modeling natural systems. These results will be used by scientists and action agencies to develop recommendations for natural resource management.
Technical Abstract: Interest in agricultural site-specific management requires adequate characterization of solute transport properties between and within soils. Undisturbed columns were collected by horizon for 3 pedons typifying the extremes of clay content in the argillic horizon. Breakthrough curves were conducted using a Br tracer and were evaluated by fitting the single and 2 region adaption of the convection-dispersion equation to outflow measurements. Saturated hydraulic conductivity measurements and methylene blue dye staining of conducting voids were also performed on cores. Dye staining indicated differences in preferential flow occurred between surface, eluvial and argillic/kandic horizons. Retardation factors were positively correlated with clay quantities and horizons possessing relatively less clay (A & E horizons) possessed the highest alpha values (quickest solute exchange rates between mobile and immobile regions). Horizons with relatively higher clay quantities had the lowest alpha and beta values, but the highest effective dispersivity values. Dye stained areas were correlated with beta, which suggested beta may be an approximation of the degree of preferential flow for these soils. For the 3 pedons studied, significant differences in alpha existed between the extremes, and thus they are interpreted to behave differently from a solute transport standpoint. Pedotransfer functions were developed for grossly estimating hydraulic and transport parameters.