|West, L - UNIVERSITY OF GEORGIA|
|Radcliffe, D - UNIVERSITY OF GEORGIA|
|Hendrix, P - UNIVERSITY OF GEORGIA|
Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 21, 2006
Publication Date: March 1, 2007
Citation: Franklin, D.H., West, L.T., Radcliffe, D.E., Hendrix, P.F. 2007. Characteristics and genesis of prefrential flow paths in a Piedmont ultisol. Soil Science Society of America Journal. 71:752-758. Interpretive Summary: A better understanding of why water moves preferentially through particular paths in soils is needed to estimate the amount of preferential flow that occurs in a given soil. This knowledge will help us estimate or model the filtering capacity of the soil or the likelihood of groundwater contamination. This study was undertaken to describe the origin, abundance and characteristics of preferential flow paths in a soil that is common to the Southern Piedmont soil. Forty, 15 cm by 60 cm columns were collected from a conventionally-tilled field. A liquid dye was used to identify the flow path that water would take through the soil and structural differences between the dyed and undyed areas were evaluated. Abundance of pores in soil and pore size of dye-stained and undyed areas were evaluated by image analysis and the two areas were described using soil blocks and thin sections. Some lower soil layers had appreciable areas of preferential flow. Preferential flow areas, indicated by the presence of dye, had about five times more area in soil pores than undyed areas. Circular dye-stained areas and the presence fecal pellets suggest that dye-stained areas were modified by burrowing organisms.
Technical Abstract: Further understanding of properties and genesis of preferential flow paths is needed to more accurately estimate the relative amount of preferential flow that occurs in a given soil. This study was initiated to describe the genesis, abundance and characteristics of preferential flow paths in a common Southern Piedmont soil. Forty, 15-cm diameter columns, 60 cm in length were collected from a conventionally-tilled field for identification and evaluation of preferential flow paths. Flow paths were identified using methylene blue dye and morphology of dye-stained area and undyed area was evaluated. Pore size and abundance for dye-stained and undyed areas were evaluated by image analysis, and fabric of the two areas was described from impregnated blocks and thin sections. Most of the Ap and BA horizons of this soil contributed to flow as indicated by complete dye staining. Only the lower part of the BA horizon and the Bt horizon had appreciable areas that were undyed suggesting preferential flow. The dye-stained areas had slightly less clay than undyed areas. Dye-stained areas, however, had about five times more pore area than undyed areas, and most of this difference was in coarse pores. Common circular morphology of dye-stained areas and the open fabric of soil in these areas with occasional fecal pellets suggest that dye-stained areas in this soil have been biologically modified. The biological modification is attributed to tree roots and burrowing organisms over the period of soil development on old and stable landscapes in the region.