COMMENTS:

Carlos M. Regalado, Axel Ritter, and Rolf Becker

Comments on "Monitoring Soil Water Content Profiles with a Commercial TDR System: Comparative Field Tests and Laboratory Calibration"
Published online 3 October 2006; doi:10.2136/vzj2006.0018L
Vadose Zone J 2006 5: 1067-1068. [Full Text] [Figures Only] [PDF]  

Jean-Paul Laurent

Response to "Comments on ‘Monitoring Soil Water Content Profiles with a TDR Commercial System: Comparative Field Tests and Laboratory Calibration’"
Published online 3 October 2006; doi:10.2136/vzj2006.0043L
Vadose Zone J 2006 5: 1069-1070. [Full Text] [Figures Only] [PDF]  

Johan A. Huisman and Harry Vereecken

Comments on "Time Domain Reflectometry Laboratory Calibration in Travel Time, Bulk Electrical Conductivity, and Effective Frequency"
Published online 3 October 2006; doi:10.2136/vzj2005.0150
Vadose Zone J 2006 5: 1071-1072. [Full Text] [Figures Only] [PDF]  

Steven R. Evett, J.A. Tolk, and T.A. Howell

Response to "Comments on ‘TDR Laboratory Calibration in Travel Time, Bulk Electrical Conductivity, and Effective Frequency’"
Published online 3 October 2006; doi:10.2136/vzj2006.0062
Vadose Zone J 2006 5: 1073-1075. [Full Text] [Figures Only] [PDF]  

ORIGINAL RESEARCH PAPERS:

Surajit Dasgupta, Binayak P. Mohanty, and J. Maximilian Köhne

Impacts of Juniper Vegetation and Karst Geology on Subsurface Flow Processes in the Edwards Plateau, Texas
Impacts of juniper and karst geology on the regional water cycle are complex and not well understood. With simulated rainfall experiments in a field we found that subsurface flow occurred in a bimodal manner, consisting of preferential flow around juniper root channels and fractures in the limestone, and pseudo-matrix flow through the soil matrix.
Published online 3 October 2006; doi:10.2136/vzj2005.0073
Vadose Zone J 2006 5: 1076-1085. [Abstract] [Full Text] [Figures Only] [PDF]  

Gerrit H. de Rooij, Olaf A. Cirpka, Frank Stagnitti, Saskia H. Vuurens, and Jan Boll

Quantifying Minimum Monolith Size and Solute Dilution from Multi-Compartment Percolation Sampler Data
We give a method to estimate the minimum sampler size for multicompartment samplers that monitor solute leaching in soils. We extend dilution theory to quantify concentration variations in a solute plume passing such a sampler. An experiment demonstrates the inadequacy of large single-cell solute collectors to determine plume characteristics.
Published online 3 October 2006; doi:10.2136/vzj2005.0101
Vadose Zone J 2006 5: 1086-1092. [Abstract] [Full Text] [Figures Only] [PDF]  

M. J. Thomasson, P. J. Wierenga, and T. P. A. Ferré

A Field Application of the Scaled-Predictive Method for Unsaturated Soil
Unsaturated soil hydraulic properties generally are highly nonlinear functions of the pressure head and are difficult to estimate. Results from this study indicate that, under proper conditions, the scaled-predictive method can be used in combination with field measured data to more readily estimate the unsaturated soil hydraulic properties.
Published online 3 October 2006; doi:10.2136/vzj2005.0104
Vadose Zone J 2006 5: 1093-1109. [Abstract] [Full Text] [Figures Only] [PDF]  

Seunghun Hyun, Perre E. Burns, Ishwar Murarka, and Linda S. Lee

Selenium(IV) and (VI) Sorption by Soils Surrounding Fly Ash Management Facilities
Se(IV, VI) sorption by soils from three ash landfill sites were well described using soil solution pH and percentage clay, thus providing a site-specific approach for assessing Se mobility. Alkaline pH and sulfate-rich leachate, typical of many ashes, reduced Se sorption. Soil attenuation of Se from ash leachate agreed well with sorption from calcium sulfate.
Published online 3 October 2006; doi:10.2136/vzj2005.0140
Vadose Zone J 2006 5: 1110-1118. [Abstract] [Full Text] [Figures Only] [PDF]  

Tjalfe G. Poulsen, Per Moldrup, Seiko Yoshikawa, and Toshiko Komatsu

Bimodal Probability Law Model for Unified Description of Water Retention, Air and Water Permeability, and Gas Diffusivity in Variably Saturated Soil
A probability law model that relates soil water retention, air and water permeability and gas diffusivity to air or water contents in undisturbed soil with bi- or multi-modal pore structure is presented. The model requires six fitting parameters. Its application to undisturbed soil samples is presented.
Published online 3 October 2006; doi:10.2136/vzj2005.0146
Vadose Zone J 2006 5: 1119-1128. [Abstract] [Full Text] [Figures Only] [PDF]  

Yu-Shu Wu, Keni Zhang, and Hui-Hai Liu

Estimating Large-Scale Fracture Permeability of Unsaturated Rock Using Barometric Pressure Data
Numerical modeling studies are presented to estimate large-scale fracture permeability in fractured vadose zone using pneumatic data. Results show (i) modeling pneumatic data provides a powerful tool for characterizing unsaturated fractured rock and (ii) permeability estimates are significantly affected by the multidimensional flow effect.
Published online 3 October 2006; doi:10.2136/vzj2006.0015
Vadose Zone J 2006 5: 1129-1142. [Abstract] [Full Text] [Figures Only] [PDF]  

G. N. Flerchinger, M. S. Seyfried, and S. P. Hardegree

Using Soil Freezing Characteristics to Model Multi-Season Soil Water Dynamics
In situ soil water release curve parameters can be derived from colocated temperature and water content sensors during freezing conditions. The methodology and accuracy of simulating soil water dynamics using soil water parameters obtained during freezing periods is assessed.
Published online 3 October 2006; doi:10.2136/vzj2006.0025
Vadose Zone J 2006 5: 1143-1153. [Abstract] [Full Text] [Figures Only] [PDF]  

William H. Albright, Craig H. Benson, Glendon W. Gee, Tarek Abichou, Scott W. Tyler, and Steven A. Rock

Field Performance of Three Compacted Clay Landfill Covers
Field-scale data are presented for compacted clay final landfill covers from sites in three distinct climates. Results demonstrate the influence of wet-dry and freeze-thaw cycles and question use of compacted clay covers.
Published online 20 November 2006; doi:10.2136/vzj2005.0134
Vadose Zone J 2006 5: 1157-1171. [Abstract] [Full Text] [Figures Only] [PDF]  

J. T. Birkholzer, S. W. Webb, N. Halecky, P. F. Peterson, and G. S. Bodvarsson

Evaluating the Moisture Conditions in the Fractured Rock at Yucca Mountain: The Impact of Natural Convection Processes in Heated Emplacement Drifts
A coupled simulation method is presented for modeling heat and moisture transport in open tunnels surrounded by fractured rock. The method was applied to study the impact of natural convection and evaporation conditions in heated emplacement drifts at Yucca Mountain, NV, the proposed geologic repository for high-level radioactive waste.
Published online 20 November 2006; doi:10.2136/vzj2005.0147
Vadose Zone J 2006 5: 1172-1193. [Abstract] [Full Text] [Figures Only] [PDF]  

Ken Kawamoto, Per Moldrup, Per Schjønning, Bo V. Iversen, Dennis E. Rolston, and Toshiko Komatsu

Gas Transport Parameters in the Vadose Zone: Gas Diffusivity in Field and Lysimeter Soil Profiles
Five gas diffusivity models were tested on gas diffusivity data collected from three 1.4-m-deep lysimeters and two field soils to a depth of 5.6 m. The three-porosity model by Moldrup et al. (2004) performed best for both shallow and deep soil layers, and predicted well the depth distributions of measured soil-gas diffusivities.
Published online 20 November 2006; doi:10.2136/vzj2006.0014
Vadose Zone J 2006 5: 1194-1204. [Abstract] [Full Text] [Figures Only] [PDF]  

Ken Kawamoto, Per Moldrup, Per Schjønning, Bo V. Iversen, Toshiko Komatsu, and Dennis E. Rolston

Gas Transport Parameters in the Vadose Zone: Development and Tests of Power-Law Models for Air Permeability
Soil-air permeability governs convective gas transport in soil. We measured air permeabilities for several soil profiles and suggested predictive air permeability models. The new models performed well in the model tests and are recommended for predicting depth variations in air permeability.
Published online 20 November 2006; doi:10.2136/vzj2006.0030
Vadose Zone J 2006 5: 1205-1215. [Abstract] [Full Text] [Figures Only] [PDF]  

Weiping Chen, Andrew C. Chang, Laosheng Wu, and Albert L. Page

Modeling Dynamic Sorption of Cadmium in Cropland Soils
A two-site sorption model derived by combining a linear equilibrium reaction model and a first-order reaction kinetics model was developed to characterize the dynamic sorption of Cd in soils. Methods were developed to study the contribution of these two processes and two types of soil were selected to demonstrate the validity of the approach.
Published online 20 November 2006; doi:10.2136/vzj2006.0037
Vadose Zone J 2006 5: 1216-1221. [Abstract] [Full Text] [Figures Only] [PDF]  

A. Nemes, W. J. Rawls, Ya. A. Pachepsky, and M. Th. van Genuchten

Sensitivity Analysis of the Nonparametric Nearest Neighbor Technique to Estimate Soil Water Retention
A nonparametric k-nearest neighbor algorithm has been developed to estimate soil water retention, adopting an ensemble approach. The algorithm proved to be a robust and accurate estimation technique that is rather insensitive to the choice of a number of algorithm options. The technique can adopt new data without the need to redevelop equations.
Published online 20 November 2006; doi:10.2136/vzj2006.0017
Vadose Zone J 2006 5: 1222-1235. [Abstract] [Full Text] [Figures Only] [PDF]  

Olga Singurindy, Brian K. Richards, Marina Molodovskaya, and Tammo S. Steenhuis

Nitrous Oxide and Ammonia Emissions from Urine-Treated Soils: Texture Effect
Urine deposition on soils is an important source of gaseous N losses to the atmosphere. We quantified ammonia and nitrous oxide emissions from urine applied to sand columns. Sand texture and the degree of saturation were the most important factors controlling ammonia volatilization and nitrous oxide emissions.
Published online 20 November 2006; doi:10.2136/vzj2006.0073
Vadose Zone J 2006 5: 1236-1245. [Abstract] [Full Text] [Figures Only] [PDF]  

Haruyuki Fujimaki, Takahiro Shimano, Mitsuhiro Inoue, and Kazurou Nakane

Effect of a Salt Crust on Evaporation from a Bare Saline Soil
The Richards equation and the convection-dispersion equation were solved numerically to predict the accumulation of salt and the evaporation rate from bare saline soil. A term for resistance of water vapor diffusion through the surface salt crust was included in the atmospheric boundary condition and the sensitivity of the resistance to salt accumulation was evaluated.
Published online 20 November 2006; doi:10.2136/vzj2005.0144
Vadose Zone J 2006 5: 1246-1256. [Abstract] [Full Text] [Figures Only] [PDF]  

Karletta Chief, Ty P. A. Ferré, and Bart Nijssen

Field Testing of a Soil Corer Air Permeameter (SCAP) in Desert Soils
Research has shown a correlation between air permeability and hydraulic conductivity. We developed a portable air permeameter compatible with a soil corer and ideal for desert soils. The accuracy and applicable shape factors of the field instrument were determined as well as the correlation of air permeability and hydraulic conductivity measurements.
Published online 20 November 2006; doi:10.2136/vzj2006.0063
Vadose Zone J 2006 5: 1257-1263. [Abstract] [Full Text] [Figures Only] [PDF]  

Quirijn de Jong van Lier, Klaas Metselaar, and Jos C. van Dam

Root Water Extraction and Limiting Soil Hydraulic Conditions Estimated by Numerical Simulation
Numerical and analytical models for microscopic root water extraction were developed and analyzed for three soils. The models or a derived nomogram can be used to show how limiting values of macroscopic root water extraction depend on transpiration rate, soil hydraulic properties, and root density.
Published online 20 November 2006; doi:10.2136/vzj2006.0056
Vadose Zone J 2006 5: 1264-1277. [Abstract] [Full Text] [Figures Only] [PDF]  

BOOK REVIEWS:

Todd H. Skaggs

Percolation Theory for Flow in Porous Media (Lecture Notes in Physics 674)
Published online 3 October 2006; doi:10.2136/vzj2006.0046br
Vadose Zone J 2006 5: 1154. [Full Text] [PDF]  

William R. Horwath

The Phanerozoic Carbon Cycle: CO₂ and O₂
Published online 3 October 2006; doi:10.2136/vzj2006.0054br
Vadose Zone J 2006 5: 1155-1156. [Full Text] [PDF]  

Bryan Weare

Monitoring and Predicting Agricultural Drought: A Global Study
Published online 20 November 2006; doi:10.2136/vzj2006.0134br
Vadose Zone J 2006 5: 1293. [Full Text] [PDF]  

Randall J. Charbeneau

Soil and Groundwater Contamination: Nonaqueous Phase Liquids
Published online 20 November 2006; doi:10.2136/vzj2006.0101br
Vadose Zone J 2006 5: 1294-1295. [Full Text] [PDF]  

TECHNICAL NOTES:

E. Unsal and J. H. Dane

Equivalent Soil Pore Geometry to Determine Effective Water Permeability
A numerical model for effective water permeability prediction as a function of water content is presented. The predicted intrinsic water permeability value compares favorably with the predicted value for air and the measured ones for water and air.
Published online 20 November 2006; doi:10.2136/vzj2006.0034
Vadose Zone J 2006 5: 1278-1280. [Abstract] [Full Text] [Figures Only] [PDF]  

J. S. Tyner, L. M. Arya, and W. C. Wright

The Dual Gravimetric Hot-Air Method for Measuring Soil Water Diffusivity
A new method is presented for collecting and analyzing data from a hot-air test. It includes a novel technique of applying two load cells, one at each end of a short soil column, to estimate the soil water profile, which eliminates the need for destructive water content sampling.
Published online 20 November 2006; doi:10.2136/vzj2006.0079
Vadose Zone J 2006 5: 1281-1286. [Abstract] [Full Text] [Figures Only] [PDF]  

W. D. Reynolds

Tension Infiltrometer Measurements: Implications of Pressure Head Offset due to Contact Sand
The contact sand layer used in tension infiltrometer measurements introduces an offset between the pressure head set in the bubble tower and the pressure head applied to the soil surface. The characteristics of the offset and its impact on tension infiltrometer results are demonstrated. Desirable attributes for contact sand material are presented.
Published online 20 November 2006; doi:10.2136/vzj2006.0098c
Vadose Zone J 2006 5: 1287-1292. [Abstract] [Full Text] [Figures Only] [PDF]  

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