Re. Phillips et al., WATER AND SOLUTE MOVEMENT IN AN UNDISTURBED, MACROPOROUS COLUMN - EXTRACTION PRESSURE EFFECTS, Soil Science Society of America journal, 59(3), 1995, pp. 707-712
Undisturbed soil columns are commonly taken to conduct water and solut
e Bow experiments, The proper boundary condition to impose at the bott
om boundary of a soil column is most difficult to define and control.
The objective of this study was to evaluate the effects of the magnitu
de of extraction pressure at the lower boundary of the soil column and
the water application rate on the amount, distribution, and percentag
e of leachate and solute drained through the soil column. Water and Cl
- were applied to a 325 by 325 by 339 mm undisturbed soil column of a
Nolin silt loam soil (fine-silty, mixed, mesic Dystric Fluventic Eutro
chrept). The soil column was placed on a collection chamber that allow
ed constant extraction pressures (0, - 1.3, or - 2.0 kPa) to be mainta
ined at the lower boundary of the soil column. Water containing solute
was applied at rates of 5, 10, and 15 mm h(-1). The leachate was part
itioned into 100 cells. Flow of water and solute through macropores in
creased as the extraction pressure maintained at the lower boundary of
the soil column increased, and as the application rate decreased. Ext
raction pressure had a greater effect on preferential flow than did ap
plication rate.