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Spatial Distribution of Water and Chloride Macropore Flow in a Well‐Structured Soil
Author(s) -
Quisenberry V. L.,
Phillips R. E.,
Zeleznik J. M.
Publication year - 1994
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/sssaj1994.03615995005800050003x
Subject(s) - macropore , loam , soil water , silt , soil science , water flow , effluent , spatial distribution , environmental science , hydrology (agriculture) , volumetric flow rate , flow (mathematics) , chemistry , geology , mathematics , environmental engineering , geotechnical engineering , geomorphology , mesoporous material , biochemistry , physics , remote sensing , geometry , quantum mechanics , catalysis
Macropore flow is recognized as an important component of water and solute transport in many soils. Our understanding of its magnitude and significance is not well developed. The objective of this experiment was to measure the effect of application rate on the magnitude and spatial distribution of macropore flow in a Maury silt loam (fine, mixed, mesic Typic Paleudalf). An undisturbed block of soil (32.5 by 32.5 by 32.5 cm) was obtained and placed on a specially designed apparatus that allowed effluent to be collected under —2.0 kPa vacuum and separated into 100 cells. Water tagged with Cl − was applied by 100 needles, 0.25‐mm i.d., which were positioned directly above the 100 collection cells. Approximately 7.5 cm of solution was applied at four application rates: 3.14, 1.97, 1.23, and 0.5 cm h −1 . A large fraction of the water and solute moved through a small percentage of the total soil for all application rates: 50% of the water and Cl − were collected in <20 and 10%, respectively, of the cells. Displacement of antecedent water by applied water was much higher for the 0.5 cm h −1 application rate than for the higher three rates. The position and spatial pattern of macropore flow remained fairly constant for the three highest flow rates. Areas of high soil water flow and high Cl − concentrations were clustered, not randomly distributed across the column. We believe these findings support our hypotheses that flow takes place in the same network of pores for similar rainfall events and that interpedal voids between tertiary structural units are important pathways of flow.