ORIGINAL RESEARCH PAPERS:

T. H. Skaggs, J. A. Poss, P. J. Shouse, and C. M. Grieve

Irrigating Forage Crops with Saline Waters: 1. Volumetric Lysimeter Studies
Forage crops (alfalfa and tall wheatgrass) were grown using synthetic agricultural drainage waters. Data are presented relating irrigation water salinity, irrigation depth, forage crop biomass production, evapotranspiration, drainage depth, and drainage water quality.
Published online 21 June 2006; doi:10.2136/vzj2005.0119
Vadose Zone J 2006 5: 815-823. [Abstract] [Full Text] [Figures Only] [PDF]  

T. H. Skaggs, P. J. Shouse, and J. A. Poss

Irrigating Forage Crops with Saline Waters: 2. Modeling Root Uptake and Drainage
HYDRUS-1D simulations of root water uptake and drainage were compared with lysimeter data collected during an experiment in which forage crops (alfalfa and tall wheatgrass) were grown using synthetic agricultural drainage waters for irrigation.
Published online 21 June 2006; doi:10.2136/vzj2005.0120
Vadose Zone J 2006 5: 824-837. [Abstract] [Full Text] [Figures Only] [PDF]  

Arnaud Boivin, Jirka Simunek, Michel Schiavon, and Martinus Th. van Genuchten

Comparison of Pesticide Transport Processes in Three Tile-Drained Field Soils Using HYDRUS-2D
Water and pesticide flow reflect various transport processes in contrasting soils. Results illustrate that using the HYDRUS-2D variably saturated flow and transport model can provide accurate simulations of drain discharge and amount of pesticides. Comparisons between observed and simulated data emphasize the main mechanisms for contrasting soils.
Published online 21 June 2006; doi:10.2136/vzj2005.0089
Vadose Zone J 2006 5: 838-849. [Abstract] [Full Text] [Figures Only] [PDF]  

P. F. Germann and D. Hensel

Poiseuille Flow Geometry Inferred from Velocities of Wetting Fronts in Soils
From 215 TDR time series wetting velocities from 0.1 to 2 millimeters per second were calculated. Their combination with Poiseuille's Law led to pore radii between 10 and 30 micrometers. HYDRUS-2D simulated well the wetting velocities with parameters for sand.
Published online 26 July 2006; doi:10.2136/vzj2005.0080
Vadose Zone J 2006 5: 867-876. [Abstract] [Full Text] [Figures Only] [PDF]  

S. Torkzaban, S. M. Hassanizadeh, J. F. Schijven, H. A. M. de Bruin, and A. M. de Roda Husman

Virus Transport in Saturated and Unsaturated Sand Columns
The transport of viruses at various water contents and solution chemistries was studied with column experiments. Our results illustrate that enhanced virus retention at lower water contents is caused by increased attachment to the solid-water interfaces and that retention by the air-water interfaces is not significant.
Published online 26 July 2006; doi:10.2136/vzj2005.0086
Vadose Zone J 2006 5: 877-885. [Abstract] [Full Text] [Figures Only] [PDF]  

Lutz Weihermüller, Roy Kasteel, and Harry Vereecken

Soil Heterogeneity Effects on Solute Breakthrough Sampled with Suction Cups: Numerical Simulations
The effect of soil heterogeneity on the solute breakthrough sampled with suction cups and the calculated transport parameters were analyzed using numerical simulations. The minimum number of suction cups required for calculating a mean breakthrough curve was estimated to be approximately 20.
Published online 26 July 2006; doi:10.2136/vzj2005.0105
Vadose Zone J 2006 5: 886-893. [Abstract] [Full Text] [Figures Only] [PDF]  

Steven R. Evett, Judy A. Tolk, and Terry A. Howell

Soil Profile Water Content Determination: Sensor Accuracy, Axial Response, Calibration, Temperature Dependence, and Precision
Capacitance, quasi-TDR, and neutron moisture meter (NMM) sensors for field soil water content sensing from within access tubes were compared in triplicate columns of three soils. Soil-specific calibrations were conducted. Using these calibrations, the capacitance and quasi-TDR methods were less accurate and more temperature sensitive than the NMM.
Published online 26 July 2006; doi:10.2136/vzj2005.0149
Vadose Zone J 2006 5: 894-907. [Abstract] [Full Text] [Figures Only] [PDF]  

P. Cannavo, F. Lafolie, B. Nicolardot, and P. Renault

Modeling Seasonal Variations in Carbon Dioxide and Nitrous Oxide in the Vadose Zone
A gas transport model based on the dusty gas theory was introduced in a one-dimensional mechanistic model to predict C and N transport in soils. This model was used to describe the transport of carbon dioxide and nitrous oxide gas, and was applied to a field experiment carried out under fallow conditions (after maize harvesting and residue incorporation in the soil).
Published online 24 August 2006; doi:10.2136/vzj2005.0124
Vadose Zone J 2006 5: 990-1004. [Abstract] [Full Text] [Figures Only] [PDF]  

A. Basile, A. Coppola, R. De Mascellis, and L. Randazzo

Scaling Approach to Deduce Field Unsaturated Hydraulic Properties and Behavior from Laboratory Measurements on Small Cores
An approach is presented for estimation of in situ hydraulic properties of a soil on the basis of a limited number of in situ measurements. The approach uses hydraulic property characteristics derived on a laboratory core, along with the maximum water content measured in the field and a scaling procedure to derive the field scale hydraulic properties.
Published online 24 August 2006; doi:10.2136/vzj2005.0128
Vadose Zone J 2006 5: 1005-1016. [Abstract] [Full Text] [Figures Only] [PDF]  

A. L. Pirani, K. R. Brye, T. C. Daniel, B. E. Haggard, E. E. Gbur, and J. D. Mattice

Soluble Metal Leaching from a Poultry Litter–Amended Udult under Pasture Vegetation
Land application of poultry litter has potential negative environmental and water-quality consequences due to soluble metals commonly present in poultry litter. Equilibrium-tension lysimeters were used to directly quantify seasonal and annual metal leaching losses from below the undisturbed root zone of tall fescue pasture vegetation.
Published online 24 August 2006; doi:10.2136/vzj2005.0138
Vadose Zone J 2006 5: 1017-1034. [Abstract] [Full Text] [Figures Only] [PDF]  

Jirka Simunek, Changming He, Liping Pang, and S. A. Bradford

Colloid-Facilitated Solute Transport in Variably Saturated Porous Media: Numerical Model and Experimental Verification
We present a numerical model that incorporates mechanisms associated with colloid and colloid-facilitated solute transport in soils. The model accounts for transport due to advection, diffusion, and dispersion, as well as for attachment to and detachment from the solid phase or the air-water interface, straining, and/or size exclusion.
Published online 24 August 2006; doi:10.2136/vzj2005.0151
Vadose Zone J 2006 5: 1035-1047. [Abstract] [Full Text] [Figures Only] [PDF]  

Mike Schwank, Timothy R. Green, Christian Mätzler, Hansruedi Benedickter, and Hannes Flühler

Laboratory Characterization of a Commercial Capacitance Sensor for Estimating Permittivity and Inferring Soil Water Content
A new relationship between relative permittivity and normalized resonant frequency measured by a capacitance probe was quantified. The instrumental error in estimated soil water content was inferred, and a characteristic radial distance of influence was deduced from numerical simulations and experiments using a coaxial metal disturbance.
Published online 24 August 2006; doi:10.2136/vzj2006.0009
Vadose Zone J 2006 5: 1048-1064. [Abstract] [Full Text] [Figures Only] [PDF]  

NOTES:

Abigail E. Faust, Ty P. A. Ferré, Marcel G. Schaap, and Andrew C. Hinnell

Can Basin-Scale Recharge Be Estimated Reasonably with Water-Balance Models?
Simplified numerical models are used for basin-scale hydrologic analysis. Use of these models requires many seemingly small choices, including the selection of underlying correlative relationships. We show that the choice of pedotransfer function results in an order of magnitude variation in predicted in-place recharge for the Tucson Basin.
Published online 21 June 2006; doi:10.2136/vzj2005.0109
Vadose Zone J 2006 5: 850-855. [Abstract] [Full Text] [Figures Only] [PDF]  

Martha P. L. Whitaker, Ty P. A. Ferré, Bart Nijssen, and Jim Washburne

Design and Testing of a Low-Cost Soil-Drying Oven
A light-bulb oven was developed to expand opportunities for soil water content measurements in K-12 schools worldwide. A variety of soil types were dried in the light bulb oven and a traditional laboratory oven. The low-technology oven operated as well as a traditional laboratory oven, at a fraction of the cost.
Published online 21 June 2006; doi:10.2136/vzj2005.0075
Vadose Zone J 2006 5: 856-859. [Abstract] [Full Text] [Figures Only] [PDF]  

C. Walker, H. S. Lin, and D. D. Fritton

Is the Tension Beneath a Tension Infiltrometer What We Think It Is?
The objective of this study was to examine the dynamics of the supply tension at the interface between the tension infiltrometer and the measured soil using a pressure transducer. The results indicate that in certain high flow situations, the actual tension may be as much as 15 mm above the set tension.
Published online 21 June 2006; doi:10.2136/vzj2005.0096
Vadose Zone J 2006 5: 860-866. [Abstract] [Full Text] [Figures Only] [PDF]  

BOOK REVIEWS:

You-Kuan Zhang

Stochastic Methods for Flow in Porous Media: Coping with Uncertainties
Published online 26 July 2006; doi:10.2136/vzj2005.0133br
Vadose Zone J 2006 5: 908. [Full Text] [PDF]  

H. Vereecken

Soil-Water-Solute-Process Characterization: An Integrated Approach
Published online 26 July 2006; doi:10.2136/vzj2005.0135
Vadose Zone J 2006 5: 909-910. [Full Text] [PDF]  

Jan Vanderborght

Hydrogeophysics
Published online 26 July 2006; doi:10.2136/vzj2006.0011br
Vadose Zone J 2006 5: 911. [Full Text] [PDF]  

Nels Ruud

Introduction to Environmental Soil Physics
Published online 26 July 2006; doi:10.2136/vzj2006.0013br
Vadose Zone J 2006 5: 912. [Full Text] [PDF]  

Thomas M. Young

Natural Attenuation of Contaminants in Soils
Published online 26 July 2006; doi:10.2136/vzj2006.0028br
Vadose Zone J 2006 5: 913-914. [Full Text] [PDF]  

Michael Young

Dryland Ecohydrology
Published online 24 August 2006; doi:10.2136/vzj2006.0053br
Vadose Zone J 2006 5: 1065. [Full Text] [Figures Only] [PDF]  

SPECIAL SECTION: PARAMETER IDENTIFICATION AND UNCERTAINTY ASSESSMENT IN THE UNSATURATED ZONE:

Jasper A. Vrugt and Shlomo P. Neuman

Introduction to the Special Section in Vadose Zone Journal: Parameter Identification and Uncertainty Assessment in the Unsaturated Zone
The guest editors introduce the specific papers featured in this issue's special section and how they address the unique challenges of parameter estimation in the vadose zone.
Published online 24 August 2006; doi:10.2136/vzj2006.0098
Vadose Zone J 2006 5: 915-916. [Full Text] [PDF]  

J. Mertens, R. Stenger, and G. F. Barkle

Multiobjective Inverse Modeling for Soil Parameter Estimation and Model Verification
A global multiobjective inverse modeling technique was adopted for vadose zone parameter estimation. Pareto optimality between goodness of fit to measured leachate and moisture content was evaluated in both unirrigated and irrigated lysimeters. The technique was used for verification of the conceptual model of equal parameters for both treatments.
Published online 24 August 2006; doi:10.2136/vzj2005.0117
Vadose Zone J 2006 5: 917-933. [Abstract] [Full Text] [Figures Only] [PDF]  

Edward M. Kwicklis, Andrew V. Wolfsberg, Philip H. Stauffer, Michelle A. Walvoord, and Michael J. Sully

Multiphase, Multicomponent Parameter Estimation for Liquid and Vapor Fluxes in Deep Arid Systems Using Hydrologic Data and Natural Environmental Tracers
Numerical models predict present-day liquid and vapor fluxes in deep, arid, alluvial systems by matching data for environmental tracers that have migrated in both liquid and vapor phases since the last major climate change. Parameter uncertainties and correlations identified during model calibration were used in Monte Carlo simulations to characterize the flux uncertainties.
Published online 24 August 2006; doi:10.2136/vzj2006.0021
Vadose Zone J 2006 5: 934-950. [Abstract] [Full Text] [Figures Only] [PDF]  

G. Schoups and J. W. Hopmans

Evaluation of Model Complexity and Input Uncertainty of Field-Scale Water Flow and Salt Transport
A method is presented to select an appropriate level of model complexity as a function of model input uncertainty. The methodology is illustrated for the prediction of field-scale seasonal crop transpiration and salt drainage given a number of point-scale measurements. We show that optimal model complexity decreases with increasing input uncertainty.
Published online 24 August 2006; doi:10.2136/vzj2005.0130
Vadose Zone J 2006 5: 951-962. [Abstract] [Full Text] [Figures Only] [PDF]  

Insa Neuweiler and Hartmut Eichel

Effective Parameter Functions for the Richards Equation in Layered Porous Media
Homogenization theory is applied to the Richards equation in a layered medium. Different ratios of gravity to capillary forces are considered and the resulting upscaled models are discussed. It is demonstrated that the effective parameter functions calculated using the assumption of capillary equilibrium are good estimates, even if the typical ratio between gravity forces and capillary forces is large.
Published online 24 August 2006; doi:10.2136/vzj2005.0127
Vadose Zone J 2006 5: 963-977. [Abstract] [Full Text] [Figures Only] [PDF]  

K.-J.S. Kung, E. J. Kladivko, C. S. Helling, T. J. Gish, T. S. Steenhuis, and D. B. Jaynes

Quantifying the Pore Size Spectrum of Macropore-Type Preferential Pathways under Transient Flow
Like a region networked with roads for human travel, so soils contain a spectrum of pores that transport chemicals and pathogens. Large macropores are the major highways; lacking a solid grasp of them is similar to driving without a roadmap. We evaluated a method to quantify macropore size spectra for predicting deep leaching of contaminants.
Published online 24 August 2006; doi:10.2136/vzj2006.0003
Vadose Zone J 2006 5: 978-989. [Abstract] [Full Text] [Figures Only] [PDF]  

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