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Measurement of Field Soil Hydraulic and Solute Transport Parameters
Author(s) -
Casey Francis X. M.,
Horton Robert,
Logsdon Sally D.,
Jaynes Dan B.
Publication year - 1998
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1998.03615995006200050003x
Subject(s) - infiltrometer , hydraulic conductivity , loam , groundwater , soil water , soil science , chemistry , tracer , hydrology (agriculture) , environmental science , geology , physics , geotechnical engineering , nuclear physics
Agricultural chemical presence in groundwater has drawn attention toward transport processes occurring in soil. Hydraulic conductivity ( K ) and water‐holding capacity of a soil have great influence on water flow and solute transport. However, much of the chemical transport to groundwater can occur through preferential flow pathways. The simplified, preferential flow, mobile‐immobile model partitions the water content (θ) into mobile (θ m ) and immobile (θ im ) domains, with solute exchange between the domains characterized by the mass‐exchange coefficient (α). In this study a sequential tracer application technique was used and K , θ, θ im , and α were estimated for a series of pressure heads ( H = 10, −30, −60, and −150 mm). This method uses a tension infiltrometer to measure both hydraulic and solute transport parameters in situ. The study took place in a no‐till corn ( Zea mays L.) field mapped as a Harps series soil (fine‐loamy, mixed, mesic Typic Calciaquoll). Unsaturated values of θ and K were distinct from the saturated values. Similarly, though less clear cut, distinctions between saturated and unsaturated values of θ im , immobile water fraction (θ im /θ), and α were observed. The medians of θ for the sequence of decreasing H values were 0.40, 0.34, 0.34, and 0.33 m 3 m ‐3 . The median K values for the same sequence of H were 108, 1.69, 1.51, and 0.72 µm s ‐1 . The median θ im /θ values for the H sequence were 0.40, 0.28, 0.25, and 0.39. The median values of α for the H sequence were 0.59, 0.015, 0.0028, and 0.0029 h ‐1 . A strong correlation between α and H suggests a velocity dependence of α.