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Immobile Water Content and Mass Exchange Coefficient of a Field Soil
Soil Science Society of America Journal
  • F.X.M. Casey, United States Department of Agriculture
  • Robert Horton, Jr., Iowa State University
  • S. D. Logsdon, United States Department of Agriculture
  • Dan Jaynes, United States Department of Agriculture
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Determining the preferential flow characteristics of a soil is important because agrichemicals can contaminate groundwater via preferential flow pathways. A model that predicts solute transport due to preferential flow is the mobile-immobile solute transport model, which partitions the total water content (θ, m3 m−3) into a mobile fraction (θm) and an immobile fraction (θim). Recently, an in situ method was proposed for determining the mobile-immobile model parameters of θim and mass exchange coefficient (α) between the fractions by using a tension infiltrometer to apply a series of four fluorobenzoate tracers. The objective of this study was to test the in situ technique at 47 sites along a transect in a ridge-till corn (Zea mays L.) field of Nicollet soil (fine-loamy, mixed, mesic Aquic Hapludoll). The immobile fraction (θim /θ) ranged from 0.394 to 0.952 with a median of 0.622. The mass exchange coefficient ranged from 0.000237 to 0.00481 min−1 with a median of 0.00123 min−1. These values are similar in magnitude and range to values reported by other investigators, and they follow the same relationships. The values of θim/θ and α along the transect indicated no obvious spatial trends or spatial correlations. Significant linear correlations did exist between α and soil water flux, α and θim, and θ and θim.


This article is published as Casey, F. X. M., R. Horton, S. D. Logsdon, and D. B. Jaynes. "Immobile water content and mass exchange coefficient of a field soil." Soil Science Society of America Journal 61, no. 4 (1997): 1030-1036. Doi: 10.2136/sssaj1997.03615995006100040006x

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F.X.M. Casey, Robert Horton, S. D. Logsdon and Dan Jaynes. "Immobile Water Content and Mass Exchange Coefficient of a Field Soil" Soil Science Society of America Journal Vol. 61 Iss. 4 (1997) p. 1030 - 1036
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