ARS | Publication request: SPATIAL VARIATION OF INFILTRATION IN A GRAZED OZARK WATERSHED

Submitted to: American Society of Agronomy
Publication Type: Abstract Only
Publication Acceptance Date: November 4, 1999
Publication Date: N/A

Technical Abstract: The partitioning of precipitation between surface runoff and infiltration affects all aspects of the surface water balance and influences agrochemical movement in the environment. Spatial variation of infiltration, therefore, is an important factor in determining how different components of the landscape perform and interact with regard to processes like nutrient transport. In this paper, data from three infiltration experiments within the same watershed will be compared and contrasted. A working hypothesis of the dominant spatial relationships of hydrologic processes within the basin is based on interpretation of these results. Sites for infiltration measurements were selected with respect to soil map unit boundaries of the soil survey, which reflect spatial relationships in parent material and slope. Three techniques (single ring, double ring, and sprinkling infiltrometers) were used to make 154 separate measurements of surface infiltration rate. Results indicate that infiltration rate varies with land use (forest vs. pasture) but this trend may in turn indicate that land use is determined by soil properties, especially slope or surface roughness and coarse fragment content. In general, infiltration was highest at lower elevations that were predominantly in hardwood forest and had either high amounts of coarse fragments (chert gravel) or macropores (rodent burrows). These findings suggest that forest sites likely serve as nutrient sinks by intercepting runoff from upland pastures.