Progress 07/01/01 to 06/30/07
Outputs
OUTPUTS: This past year two contributions were made in this research project. The first deals with identifying the influence of soil microstructure on water content measurements using electromagnetic measurement techniques. The second contribution came from heat-pulse-based probes that were developed, constructed and evaluated for estimation of water flux in soil. A numerical modeling approach was developed to predict the dielectric properties of heterogeneous particulate materials with arbitrary microstructures. The effective permittivities, convergence behavior, and dispersion behavior of the simulations were sensitive to both microstructure and the extent of multiple scattering included in the models, illustrating how the macroscopic properties depend significantly on the microscopic details of the interactions. In contrast to other approaches, the interative multipole method can model both the frequency and spatial dependencies of the electromagnetic properties of particulate
materials, as well as a wide variety of microstructures, including polydisperse and hierarchical systems. Determination of soil water flux is of interest for understanding snowmelt dynamics but accurate measurement techniques are lacking. Although a method was suggested in the late 1950's based on heat transport, only in the past decade have measurement capabilities improved to the point that this technique is gaining interest. We designed and constructed water flux heat-pulse probes and evaluated these in a forest setting as a means of determining snow melt water fluxes below snowpack in the T.W. Daniel Experimental Forest site. These sensors are part of an extensive instrumentation facility we have installed at the site.
PARTICIPANTS: T.W. Daniels Experimental Forest
TARGET AUDIENCES: Water and irrigation district managers. USDA, EPA, NASA research scientists and engineers. Congressional constituency and Experiment Station Directors.
Impacts
A novel model was developed to describe the permittivity-water content relationship for highly aggregated soils where electromagnetic measurements (e.g., TDR, GPR, Aircraft, Satellite) for water content determination are used. This model highlights the influence aggregate water phase configuration has on dielectric-based measurements for water content, which up to this point had been primarily attributed to bound water in soils. Four novel water flux probes were developed and installed in the T. W. Daniel Experimental Forest Site to provide detailed information on snowmelt dynamics under four vegetation types. Sensors provide information on snowmelt infiltration rates which will aid in linking subsurface and above-ground understanding of Utah's primary water resource. Soil infiltration rates under spring snowmelt have not previously been available. Our objective is to link subsurface and above-ground measurements for more comprehensive measurement and modeling of
Utah's primary water resource. We developed sensing capability for near surface field-scale monitoring of soil properties for evaluating temporal effects on water and solute transport. Reclamation of saline and sodic soils requires field-scale information that is presently unavailable or very costly to obtain. This work seeks to improve access to this information. Tremendous water savings are possible world-wide using sensor controlled irrigation scheduling but only recently has there been a water content sensor with reliable measurement capability that also controls existing irrigation systems. Blonquist et al, (2005, 2006) demonstrated up to 50% water savings with sensor-based irrigation management when compared to a typically managed residential system. A novel approach to mapping small watershed soils using electromagnetic induction has demonstrated potential to enhance extraction of soil textural properties, which are important inputs to modeling and prediction of watershed
hydrology. As a result, one of our group is now playing a key role for development of an NSF-funded hydrological measurement facility through the Consortium of Universities for Advancement of Hydrologic Science (CUAHSI). The optimal water application rate for leaching salts can be determined by considering the cost of water and cost of continued application (pumping cost, labor, time limits) in the analysis. A saturated flux rate between 1 and 0.1 inches per hour was found to be optimal based on costs in several western US states.
Publications
- Doyle, T.E., D.A. Robinson, S.B. Jones, K.H. WArnick and B.L. Carruth 2007. Modeling the permittivity of two-phase media containing monodisperse spheres: Effects of microstructure and multiple scattering. Physical Review B 76(5):054203.
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Progress 01/01/06 to 12/31/06
Outputs
This past year three significant contributions were made in this research project. The first deals with identifying the influence of soil structure on water content measurements using electromagnetic measurement techniques. The second considered the influence of water application rate on salt leaching efficiency in aggregated porous media. The third contribution came from heat-pulse-based probes that were developed, constructed and evaluated for estimation of water flux in soil. Electromagnetic measurements for water content range from Time Domain Reflectometry (TDR) at a point scale to ground penetrating radar at the field scale up to remotely sensed information from aircraft or satellites. The soil permittivity is related to the water content because of the contrast in the permittivity of water compared to that of solid minerals and air. We found that in well aggregated soils there is a significant influence of the soil structure on the measured permittivity. This
influence was shown to cause a significant shift in the permittivity-water content relationship leading to a bi-modal response, which we developed a model for. A masters thesis addressed the issue of water application rate on the salt leaching efficiency in aggregated porous media. We considered the tradeoff between applying water under flooded conditions at a high water flow rate to that of a reduced flow rate requiring more time. This range of flow rates allowed a comparison of the cost benefit based on nominal costs of water and labor (time factor). Determination of water flux in soil has long eluded scientists because of the difficulty in measuring this important hydrologic parameter. Although a method was suggested in the late 1950's based on heat transport, only in the past decade have measurement capabilities improved to the point that this technique is gaining interest. We designed and constructed water flux heat-pulse probes and evaluated these in infiltration tests as a
means of determining snow melt water fluxes flowing into soil in the T.W. Daniel Experimental Forest site. These sensors are part of an extensive instrumentation facility we have installed at the site and measured data will be output to the water initiative website. Because the sensor also measures temperature, frozen soil can be detected and when coupled with TDR, water content can also be determined in frozen soils.
Impacts
A novel model was developed to describe the permittivity-water content relationship for highly aggregated soils where electromagnetic measurements (e.g., TDR, GPR, Aircraft, Satellite) for water content determination are used. This model highlights the influence aggregate water phase configuration has on permittivity measurements, which up to this point had been primarily attributed to bound water in soils. The optimal water application rate for leaching salts can be determined by considering the cost of water and cost of continued application (pumping cost, labor, time limits) in the analysis. A saturated flux rate between 1 and 0.1 inches per hour was found to be optimal based on costs in several western US states. Four water flux probes installed in the T. W. Daniel Experimental Forest Site will provide detailed information on snowmelt dynamics under four vegetation types. Soil infiltration rates under spring snowmelt have not previously been available. Our goal is
to link subsurface and above-ground measurements for more comprehensive measurement and modeling of Utah's primary water resource. This research will demonstrate an approach for separating subsurface versus surface water flow for enhanced forecasting of spring snowmelt runoff.
Publications
- Henry, A., J. Norton, S.B. Jones, J. Chard and B. Bugbee. 2006. Design and maintenance of an axenic plant culture system to facilitate optimal growth in long-term studies. J. Environ. Qual. 35:590-598.
- Heinse, R., K.S. Lewis, S.B. Jones, G. Kluitenberg, R.S. Austin, P. Shouse and G.E. Bingham. 2006. Integration of heat capacity and electrical conductivity sensors for root module water and nutrient assessment. SAE Technical Paper no. 2006-01-2211.
- Okwany, R.O. 2006. Leaching Efficiency Optimization as a Function of Water Application Rate in Aggregated Porous Media, M.S. Thesis, Utah State University.
- Blonquist, J.M. Jr., S.B. Jones, I. Lebron and D.A. Robinson. 2006. Micro-structural and phase configuration effects determining water content: Dielectric relationships of aggregated porous media. Water Resour. Res. 42(5), W05424, doi:10.1029/2005WR004418.
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Progress 01/01/05 to 12/31/05
Outputs
We made progress in several areas including development of an instrumented soil column as part of a graduate class in vadose zone transport. The instrumentation included TDR for water content and electrical conductivity, thermocouples for temperature, tensiometers for matric potential, and oxygen and carbon dioxide sensors. Students used Hydrus 1D to inverse fit soil properties from temporal measurements after wetting and drying the soil. Students presented a poster in the S-1 section of the Tri-society meetings in Salt Lake City this Fall. Soil mapping in water sheds using electromagnetic induction for electrical conductivity measurements was explored as a means of characterizing soil properties. Measurements are related to soil texture and other properties of interest from distributed sampling. A vertical 2m deep by 1x1m instrumented plot was established with TDR probes and thermocouples for characterization of the vertical profile measurement character of the EMI
instrument. An insitu dielectric sensor using time domain transmissometry was used to compare weather station irrigation scheduling against sensor-based control. The sensor-based control provided the minimum water use but was highly dependent upon the sprinkler application efficiency at the sensor. Temporal variations in rootzone water content were tracked and related to evapotranspiration rates. A solute transport study in aggregated porous media was initiated using small columns. The purpose was to determine an optimal leaching rate for field-scale removal of salts from irrigation application rate adjustment.
Impacts
Tremendous water savings are possible world-wide using sensor controlled irrigation scheduling but only recently has there been a water content sensor with reliable measurement capability that also controls existing irrigation systems. One recent (Blonquist et al, 2005) and one forthcoming publication (Blonquist, 2006) clearly demonstrate up to 50% water savings with sensor-based management when compared to a typically managed residential system. Students obtained an in-depth understanding of solute transport using state-of-the art instrumentation installed in a laboratory soil column, which they developed and constructed. A novel approach to mapping small watershed soils using electromagnetic induction has demonstrated potential to enhance extraction of soil textural properties, which are important inputs to modeling and prediction of watershed hydrology. As a result, one of our group is now playing a key role for development of an NSF-funded hydrological measurement
facility through the Consortium of Universities for Advancement of Hydrologic Science (CUAHSI).
Publications
- Blonquist Jr., J.M., S.B. Jones, and D.A. Robinson. 2005. Water Conservation from Precise Irrigation Scheduling Using a Subsurface Electromagnetic Soil Moisture Sensor. Technical Session Proceedings of the 26th Annual Irrigation Association International Irrigation Show. November 6-8, 2005, Phoenix, AZ.
- Steinberg, S.L., S.B. Jones, M. Xiao, L. Reddi and G. Kluitenberg, D. Or, J.I.D. Alexander, N. Daidzic, M. Tuller. 2005. Challenges to understanding fluid behavior in plant growth media under microgravity. SAE Technical Paper no. 2005-01-2973.
- Steinberg, S., G. Kluitenberg, S.B. Jones, N. Daidzic, L. Reddi, M. Xiao, M. Tuller, R. Newman, D. Or and I. Alexander. 2005. Physical and hydraulic properties of baked ceramic aggregates used for plant growth medium. J. Amer. Soc. Hort. Sci. 130(5):767-774.
- Blonquist, J.M.Jr., R. Heinse, P. Ditthakit, R.W. Mace and S.B. Jones. 2005. An Instrumented Soil Column for Teaching Unsaturated Flow and Transport Processes. Agronomy Abstracts, ASA, Madison, WI.
- Robinson, D.A., D. Chandler and S.B. Jones. 2005. An Overview of Advances in Water Content Sensing for Small Watersheds and Ecohydrological Studies. Eos Trans. AGU, 86(18), Jt. Assem. Suppl., Abstract H21E-03.
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Progress 01/01/04 to 12/31/04
Outputs
We have initiated work in three different areas related to the objectives of this project. The major accomplishments for 2004 were i) development of the soil mapping project in cooperation with Juniper Systems with preliminary GPS and EM-38 field-scale measurements realized using software enhancements to couple output, ii) initiation of solute transport work in a column study using variable application rates to determine optimal leaching efficiency, iii) an improved and updated version of WINTDR software (v. 6.1) supporting TDR applications for monitoring solute transport, iv) another microgravity flight experiment brought us closer to understanding effects of microgravity on porous media fluid physics relative to growing plants in reduced gravity environments.
Impacts
Soil surface stability in rangelands in the intermountain West is strongly linked to the presence of soil biocrusts, which have an important role to play in the ecohydrology of semi-arid rangelands. The biocrusts are nitrogen fixers and excess nitrogen becomes available to the surrounding vegetation. A key component to understanding the ecohydrological role of biocrusts is to develop sensors at a pertinent scale that will provide high temporal resolution data regarding surface / biocrust water content. In addition to sensing soil moisture in the near surface, we will develop capabilities for field-scale monitoring of soil properties for evaluating temporal effects on water and solute transport. Reclamation of saline and sodic soils requires field-scale information that is presently unavailable or very costly to obtain. This work seeks to improve access to this information. Work on optimizing fluxes of gas and liquid in plant growth media will focus on engineering
geometries and materials for an improved rooting environment.
Publications
- Jones, S.B., D. Or, G.E. Bingham and T.S. Topham. 2004. Automated Systems for Oxygen Diffusion Measurements in Porous Media at 1g and 0g. Proceedings of the 9th Biennial ASCE Aerospace Division International Conference on Engineering, Construction and Operations in Challenging Environments (Earth & Space 2004). March 7-10, 2004, League City/Houston, TX.
- Steinberg, S. L., J.I.D.Alexander, D. Or, N. Daidzic, S.B. Jones, L. Reddi, M. Tuller, G. Kluitenberg and M. Xiao. 2004. Flow and distribution of fluid phases through porous plant growth media in microgravity. Proceedings of the 9th Biennial ASCE Aerospace Division International Conference on Engineering, Construction and Operations in Challenging Environments (Earth & Space 2004). March 7-10, 2004, League City/Houston, TX.
- Or, D, M. Tuller And S.B. Jones. 2004. Liquid-gas interfacial configurations in angular pores under microgravity. Proceedings of the 9th Biennial ASCE Aerospace Division International Conference on Engineering, Construction and Operations in Challenging Environments (Earth & Space 2004). March 7-10, 2004, League City/Houston, TX.
- USU Soil Physics Group. 2004. WinTDR: A Windows-based time domain reflectometry program for measurement of soil water content and electrical conductivity. Release 6.1. USU Soil Physics Group, Logan, Utah. http://129.123.13.101/soilphysics/wintdr/documentation.htm#Manual Fall2004
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Progress 01/01/03 to 12/31/03
Outputs
The major accomplishments for 2003 were i) novel hydraulic conductivity models characterizing swelling and macroporous and structured soil behavior were published, ii) work detailing models that describe soil dynamics and shrinkage behavior were published, iii) an updated version of WINTDR software supporting TDR applications for monitoring water and solute transport was released.
Impacts
Models developed under this grant provide improved understanding of pore-scale processes affecting field soil structure and management of water and solutes leading to reduced compaction for improved crop yield and enhanced sustainable management practices.
Publications
- Or, D., 2002. Physical processes affecting microbial habitats and activity in unsaturated porous media. Agric. Sci. 7(2):39-45.
- Or, D., and M. Tuller, 2003. Hydraulic conductivity of unsaturated fractured porous media: Flow in a cross-section. Adv. Water Resour., Vol.26, No.8, 883-898.
- Tuller, M. and D. Or, 2003. Hydraulic functions for swelling soils: pore scale considerations. J. Hydrology 272:50-71.
- Ghezzehei, T.A., and D. Or. 2003. Stress induced shrinkage of isolated pores in a wet soil matrix. Water Resour. Res. 39(3) 1067,10.1029/2001WR001137.
- Mmolawa, K. B., and D. Or, 2003. Experimental and numerical evaluation of analytical volume balance model for soil water dynamics under a drip irrigation. Soil Sci. Soc. Am. J. 67: 1657-1671.
- Ghezzehei, T.A., and D. Or. 2003. Dynamics of pore space in soil aggregate bed under static and dynamic external loads. Soil Sci. Soc. Am. J. 67:12-16.
- USU Soil Physics Group. 2003. WinTDR: A Windows-based time domain reflectometry program for measurement of soil water content and electrical conductivity. Release 6.0. USU Soil Physics Group, Logan, Utah.
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Progress 01/01/02 to 12/31/02
Outputs
The main accomplishments made during this year were: (i) development of new models for hydraulic conductivity functions for swelling (clayey) soils, and for macroporous and structured soils; (ii) new models for closure of isolated pores embedded in wet soils under transient stress conditions towards better description of soil compaction and its impact on hydraulic properties; (iii) refining methods for using TDR in highly saline soils.
Impacts
The Impact this year's results should improve aspects of field soil structure management thereby reducing impact of compaction and costs of tillage, enhancing crop yields due to improved soil tilth management, and improving conditions for compliance with EPA regulations for agrochemicals transport.
Publications
- Leij, F.J., T.A. Ghezzehei, and D. Or. 2002. Analytical models for soil pore size distribution after tillage. Soil Sci. Soc. Am. J. 66:1104-1114.
- Tuller, M. and D. Or, 2002. Unsaturated hydraulic conductivity of structured porous media: A review of liquid configuration based models. Vadose Zone J. 1(1):14-37.
- Bialkowski, S., L. M. Dudley, and D. Or. 2002. Using Expectation Maximization to obtain dielectric relaxation time spectra of aqueous montmorillonite clay suspensions. J. Applied Spectroscopy 56(11):1470-1474.
- Or, D., and M. Tuller. 2002. Cavitation in porous media under tension. Water Resour. Res. 38(5) 10.1029/2001WR000282.
- Or, D., 2002. Physical processes affecting microbial habitats and activity in unsaturated porous media. Agric. Sci. 7(2):39-45. Gee. G.W., and D. Or. 2002. Particle Size Analysis. In: Dane J. and C. Topp. (ed.) Methods of Soil Analysis, ASA, Madison, WI.
- Berli, M. and D. Or, 2002. Modeling bulk soil compaction using a rheologically based pore closure model. In: L. Vulliet, B. Schrefler and L. Laloui (Editors), Environmental Geomechanics, Monte Verita, Switzerland.
- Jones, S., Bingham, G.E., D. Or and R.C. Morrow. ORZS: Optimization of Root Zone Substrates for Microgravity. The 32nd International Conference on Environmental Systems (ICES), SAE Technical Paper 2002-01-2380, San Antonio, Texas, USA, July 15-18, 2002.
- Tuller, M., and D. Or, 2002. Hydraulic properties of partially saturated fractured porous media, Proceedings of the International Groundwater Symposium, LBNL, Berkeley, California, March 25-28, pp.416-420, ISBN 90-805649-4-X.
- Jones, S.B. and D. Or. 2002. Dielectric and acoustic monitoring of water content and volume changes in ear corn drying bins. Agronomy Abstracts, ASA, Madison, WI.
- Or, D., 2002. Physical processes affecting microbial habitats and activity in unsaturated porous media. Agronomy Abstracts, ASA, Madison, WI.
- Berli, M. and Or, D., 2002. Modeling bulk soil deformation using rheological properties and micro scale pore closure. Soil Science Society of America, Indianapolis, IN. Agronomy Abstracts. ASA, Madison, WI.
- Jones, S.B. and D. Or. 2002. Automated gas diffusion measurements in coarse-textured plant growth media for microgravity studies. Agronomy Abstracts, ASA, Madison, WI.
- Jones, S.B., and D. Or. 2002. Thermal effects on bulk permittivity of porous mixtures containing bound water. J. Non Crystalline Solids 305(1-3):247-254.
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Progress 01/01/01 to 12/31/01
Outputs
The main accomplishments made during this year were: (i) development of models for hydraulic conductivity functions in unsaturated soils based on flow in angular pore space; (ii) expansion of soil rheological models to describe soil compaction under steady and transient loads (i.e., passage of farm implements); (iii) Development of methods for using TDR for grain moisture measurements in drying bins.
Impacts
The primary impact this year's results is substantial improvement in predicting and managing field soil structure to reduce soil compaction towards reduced costs of tillage, enhanced water use efficiency, and better crop yields due to improved soil tilth management.
Publications
- Wraith, J.M., and D. Or. 2001. Soil water characteristic determination from concurrent water content measurements in reference porous media. Soil Sci. Soc. Am. J. 65:1659-1666.
- Wraith J.M., D. Or, and S. B. Jones. 2001. Dielectric properties of bound water: application to porous media surface area and grain moisture determination. Proc. TDR 2001: Proceedings of the 2nd International Symposium and Workshop on Time Domain Reflectometry for Innovative Geotechnical Applications. Northwestern University, September 5-7, 2001, Evanston, Illinois.
- Or, D and S.B. Jones. 2001. Thermal and geometrical effects on bulk permittivity of porous mixtures containing bound water. Proceedings of the first workshop on application of TDR techniques in Agriculture. July 17-18, 2001. Campinas, SP, Brasil.
- Or, D and S.B. Jones. 2001. Extending TDR measurement range in saline soils using frequency-domain methods. Proceedings of the first workshop on application of TDR techniques in Agriculture. July 17-18, 2001. Campinas, SP, Brasil.
- Or, D., and M. Tuller. 2001. Cavitation during desaturation of porous media under tension. Water Resour. Res. (in press).
- Ryel, R.J., M.M. Caldwell, C.K. Yoder, D. Or, and A.J. Leffler. 2001. Hydraulic redistribution in a stand of Artemisia tridentata: Evaluation of benefits to transpiration assessed with a simulation model. Oecologia (in press).
- Or, D., and T.A. Ghezzehei. 2001. Modeling post-tillage structural dynamics in aggregated soil: A review. Soil Tillage Res. 1651:1-19.
- Leij, F.J., T.A. Ghezzehei, and D. Or. 2001. Modeling the dynamics of the soil pore size distribution. Soil Tillage Res. 1651:xx-xx. Jones, S.B., J.M. Wraith, and D. Or. 2001. Time Domain Reflectometry (TDR) measurement principles and applications. Hydrol. Proc. (in press). Jones, S.B., and D. Or. 2001. Thermal and geometrical effects on bulk permittivity of porous mixtures containing bound water. J. Non-Crystalline Solids (in press).
- Or, D., and M. Tuller. 2001. Adsorption and Capillarity in Variably Saturated Porous Media Pore Scale Hydrostatic and Hydrodynamic Considerations. (invited) In: Selim M., and D.L. Sparks (eds.) Physical and Chemical Processes of Water and Solute Transport and Retention in Soils, SSSA Special Publication 56, 1-50.
- Gee. G.W., and D. Or. 2001. Particle Size Analysis. In: Dane J. and C. Topp. (ed.) Methods of Soil Analysis, ASA, Madison, WI (in press).
- Warrick, A., and D. Or. 2001. Effect of gravity on steady infiltration from spheroids. In: J.R. Philip Tribute, Geophysical Monograph Series, American Geophysical Union, Washington, DC.
- Or, D., and J.M. Wraith. 2001. Soil Water Content and Potential. In: Warrick A. (ed.), Soil Physics Companion. CRC Press, Boca Raton, Fl.
- Tuller, M., and D. Or. 2001. Hydraulic functions for macroporous soils. ASAE Proceedings of the 2nd International Symposium on Preferential Flow, Honolulu, Hawaii, January 3-5. pp. 37-40. ISBN 1-892769-14-X.
- Wraith, J.M., D. Or. and S.B. Jones. 2001. Dielectric properties of bound water: Application to porous media surface area and grain moisture determination. TDR 2001: Proceedings of the Second International Symposium and Workshop on Time Domain Reflectometry for Innovative Geotechnical Applications. Northwestern University, September 5-7, 2001, Evanston, Illinois.
- Jones S.B., G.E. Bingham, D. Or, R.C. Morrow and I.G. Podolsky. 2001. Optimization of the root zone substrates (orzs): microgravity modeling and validation. ASGSB Abstracts.
- Jones, S.B. and D. Or. 2001. Thermal and geometrical effects on bulk permittivity of porous mixtures containing bound water. Abstracts to the 1st International Conference on Dielectric Spectroscopy. 12-15 March 2001, Jerusalem, Israel.
- Jones, S.B. and D. Or. 2001. Automated Frequency Domain Analysis for Extending TDR Measurement Range in Saline Soils. TDR 2001: Proceedings of the 2nd International Symposium and Workshop on Time Domain Reflectometry for Innovative Geotechnical Applications. Northwestern University, September 5-7, 2001, Evanston, Illinois.
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Progress 01/01/00 to 12/31/00
Outputs
The main accomplishments for this year include: (i) incorporation of hydrodynamic aspects to models for capillary condensation and adsorption in angular pores representing soils and rocks; (ii) further development of models and measurement techniques for the behavior of soil aggregate beds under transient load (i.e., passage of farm implements); and (iii) A review of root zone solute dynamics under drip irrigation.
Impacts
The Impact this year's results should improve aspects of field soil structure management for better hydraulic and structural properties towards reducing impact of compaction and costs of tillage, enhancing crop yields due to improved soil tilth management, and improving conditions for compliance with EPA regulations for agrochemicals transport.
Publications
- (7) Serbin G, Or D., and D. Blumberg. 2000. Thermodielectric effects on radar backscattering from wet soils. IEEE TGARS (in press).
- (8) Mmolawa, K. B., and D. Or, 2000. Water and solute dynamics under a drip irrigated crop: Experiments and analytical model. Transactions of the ASAE (in press).
- (9) Or, D., 2001. Who invented the tensiometer? Soil Sci. Soc. Am. J. 65:000-000. (10) Tuller, M. and D. Or, 2000. Hydraulic conductivity of variably saturated porous media: Film and corner flow in angular pore space, Water Resour. Res. (in press)
- (11) Ghezzehei, T.A., and D. Or. 2000. Rheological properties of wet soils and clays under steady and oscillatory stresses. Soil Sci. Soc. Am. J. (in press).
- (12) Stothoff, S., and D. Or. 2000. A Discrete-Fracture Boundary Integral Approach to Simulating Coupled Energy and Moisture Transport in a Fractured Porous Medium. In: Dynamics of Fluids in Fractured Rocks: Concepts and Recent Advances, Geophysical Monograph Series, American Geophysical Union, Washington, DC
- (1) Or, D. and T.A. Ghezzehei. 2000. Dripping into cavities from unsaturated fractures under evaporative conditions. Water Resour. Res. 36:381-393.
- (2) Ghezzehei, T.A., and D. Or. 2000. Dynamics of soil aggregate coalescence governed by capillary and rheological processes. Water Resour. Res. 36:367-379.
- (3) Or., D., F.J., Leij, V. Snyder, and T.A. Ghezzehei. 2000. Stochastic model for post-tillage soil pore size evolution. Water Resour. Res. 36:1641-1652.
- (4) Microgravity effects on water supply and substrate properties in porous matrix root support systems. 2000. Bingham, G.E., S.B. Jones, D. Or., D., I.G. Podolski, M.A. Levinskikh, V.N. Sytchov, T. Ivanova, P. Kostov, S. Sapunova, I. Dandolov, D.B. Bubenheim, G. Jahns. Acta Astronautica 47:1-10.
- (5) Or, D., U. Shani, and A.W. Warrick. 2000. Subsurface tension permeametry. Water Resour. Res. 36:2043-2053.
- (6) Mmolawa, K. B., and D. Or, 2000. Root zone solute dynamics under drip irrigation: A review. Plant and Soil 222:161-189.
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Progress 01/01/99 to 12/31/99
Outputs
The main accomplishments made during the third year of this project were: (i) further development of new models for capillary condensation and adsorption in angular pores including hydrodynamic aspects; (ii) measurement of soil rheological properties and modeling the response of wet soil aggregate beds to transient loading (i.e., passage of farm implements); (iii) Development of methods for using TDR in highly saline soils.
Impacts
This year's results should improve aspects of field soil structure management thereby reducing impact of compaction and costs of tillage, enhancing crop yields due to improved soil tilth management, and improving conditions for compliance with EPA regulations for agrochemicals transport.
Publications
- Friel, R., and D. Or. 1999. Frequency analysis of time domain reflectometry (TDR) with applications to dielectric spectroscopy of soil constituents. Geophysics 64(3):1-12.
- Coelho, F. E., and D. Or. 1999. A model for soil water and matric potential distribution under drip irrigation with water extraction by roots. Pesq. Agropec. Bras. Brasilia 34(2):225-234 (in Portuguese).
- Wraith, J.M., and D. Or. 1999. Temperature effects on time domain reflectometry measurement of soil bulk dielectric constant: experimental evidence and hypothesis development. Water Resour. Res. 35:361-369.
- Or, D., and J.M. Wraith. 1999. Temperature effects on time domain reflectometry measurement of soil bulk dielectric constant: A physical model. Water Resour. Res. 35:371-383.
- Coelho, F. E., D. Or, and V.F. De Sousa. 1999. Evaluation of Soil Hydraulic Parameters for Soil Water Distribution Models Under Drip Irrigation. Pesq. Agropec. Bras., Brasilia 34(4):651-657 (in Portuguese).
- Jones, S.B., and D. Or. 1999. Microgravity Effects on Water Flow and Distribution in Unsaturated Porous Media: Analyses of Flight Experiments. Water Resour. Res. 35:929-942.
- Stothoff, S, D. Or, D.P. Groeneveld, and S.B. Jones. 1999. The effect of vegetation on infiltration in shallow soils underlain by fissured bedrock. J. Hydrology 218:169-190.
- Coelho, F. E., and D. Or. 1999. Root distribution and water uptake patterns under surface and subsurface drip irrigation. Plant and Soil 206:123-136.
- Tuller M., D. Or, and L.M. Dudley. 1999. Adsorption and capillary condensation in porous media - liquid retention and interfacial configurations in angular pores. Water Resour. Res. 35:1949-1964.
- Or, D., and M. Tuller. 1999. lLquid retention and interfacial area in variably saturated porous media: upscaling from single pore to sample scale model. Water Resour. Res. 35:3591-3606.
- Or, D., and J. M. Wraith. 1999. A New TDR-Based Soil Matric Potential Sensor. Water Resour. Res. 35:3399-3407.
- Or, D. and T.A. Ghezzehei. 1999. Dripping into subterranean cavities from unsaturated fractures under evaporative conditions. Water Resour. Res. (in press)
- Ghezzehei, T.A., and D. Or. 1999. Dynamics of soil aggregate coalescence governed by capillary and rheological processes. Water Resour. Res. (in press)
- Or, D., and J.M. Wraith. 1999. Soil Water Content and Water Potential Relationships. In: Sumner M. (ed.) Handbook of Soil Science, pp. A53-A85. CRC Press, Boca Raton, Fl.
- Or, D., and M. Tuller. 1999. Adsorption and Capillarity in Variably Saturated Porous Media Pore Scale Hydrostatic and Hydrodynamic Considerations. (invited) In: Selim M., and D.L. Sparks (eds.) Physical and Chemical Processes of Water and Solute Transport and Retention in Soils", SSSA Special Publication, (in press).
- Dasberg, S. and D. Or. 1999. Drip Irrigation (new book). Springer-Verlag, Heidelberg.
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Progress 01/01/98 to 12/31/98
Outputs
The main accomplishments made during the second year of this project were: (i) development of new models for capillary condensation and adsorption in angular pores; (ii) improved modeling for aggregate rejoining and their effects on soil pore sizes; (iii) new method for measurement of soil wettable surface area and bound water based on TDR and thermodielectric effects. The impact the results should improve field soil management thereby reducing costs of tillage, enhancing crop yields due to improved soil tilth management, and improving conditions for compliance with EPA regulations for agrochemicals transport.
Impacts
(N/A)
Publications
- Coelho, F.E. and D. Or. 1998. A Model for Soil Water Distribution under Drip Irrigation with Root Uptake. Pesq. Agropec. Bras. Brasilia (in Portuguese - in press).
- Wraith, J.M. and D. Or. 1998. Temperature effects on time domain reflectometry measurement of soil bulk dielectric constant: experimental evidence and hypothesis development. Water Resour. Res. (in press).
- Or, D. and J.M. Wraith. 1998. Temperature effects on time domain reflectometry measurement of soil bulk dielectric constant: A physical model. Water Resour. Res.(in press).
- Jones, S.B. and D. Or. 1998. Microgravity Effects on Water Flow and Distribution in Unsaturated Porous Media: Analyses of Flight Experiments. Water Resour. Res. (in press).
- Coelho, F.E. and D. Or. 1998. Root Distribution and Water Uptake Patterns under Surface and Subsurface Drip Irrigation. Plant and Soil (in press).
- Or, D. and J.M. Wraith. 1998. Soil Water Content and Water Potential Relationships. In: Sumner M. (ed.) Handbook of Soil Science, CRC Press (in press).
- Tuller, M., D. Or and L.M. Dudley, 1998. New pore geometry models for adsorptive and capillary water retention - predictions and upscaling considerations. p. 168. ASA abstracts. ASA, Madison, WI.
- Or, D. and J.M. Wraith. 1998. A new TDR-based matric potential sensor. p. 31. Proc. ISSS 16th World Congress of Soil Science (manuscript on CD), Aug. 20-26, 1998, Montpellier, France.
- Or, D., M. Tuller and L.M. Dudley, 1998. Adsorption and capillary condensation in porous media. p. 169. ASA abstracts. ASA, Madison, WI.
- Ghezzehei T.A. and D. Or, 1998. Post tillage soil aggregate rejoining - sintering analog, p. 169. ASA abstracts. ASA, Madison, WI.
- Wraith J.M. and D. Or. 1998. Thermo-dielectric estimation of soil specific surface area using TDR. p. 171. ASA abstracts. ASA, Madison, WI.
- Gee, G.W., A.L. Ward, G.S. Campbell and D. Or. 1998. Effects of hydraulic nonequilibrium on pressure plate data. p. 168. ASA abstracts. ASA, Madison, WI.
- Jones, S.B. and D. Or. 1998. Design of Porous Media for Optimal Liquid and Gaseous Fluxes to Plant Roots. Soil Sci. Soc. Am. J. 62:563-573.
- Wraith J.M. and D. Or. 1998. Nonlinear Parameter Estimation Using Spreadsheet Software. J. Nat. Resour. Life. Sci. Edu. 27:13-19.
- Jones, S.B. and D. Or. 1998. Particulated Growth Media for Optimal Liquid and Gaseous Fluxes to Plant Roots in Microgravity. Adv. Space Res. (in press).
- Jones, S.B. and D. Or. 1998. A Capillary-Driven Root Module for Plant Growth in Microgravity. Adv. Space Res. (in press).
- Friel, R. and D. Or. 1998. Frequency Analysis of Time Domain Reflectometry (TDR) with Applications to Dielectric Spectroscopy of Soil Constituents. Geophysics (in press).
- Stothoff, S., O. Chadwick, D. Or, D. Woolhiser, D.P. Groeneveld and R. Feadors. 1998. Coupling deep percolation to geomorphic response over a glacial cycle in a semiarid watershed. F. 290. AGU Fall Meeting. San Francisco, CA.
- Tuller, M., D. Or and L.M. Dudley. 1998. Pore scale retention and interfacial processes in partially saturated porous media. F. 370. AGU Fall Meeting. San Francisco, CA.
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Progress 01/01/97 to 12/31/97
Outputs
The main accomplishments made during the second year of this project were: (i) design and testing of a new tension infiltrometer for characterization of subsurface unsaturated hydraulic properties, ii) new theoretical model for post-tillage pore size evolution during wetting; (iii) Model-based correction factors were developed to account for temperature effects on time domain reflectometry measurements of soil water content.
Impacts
(N/A)
Publications
- Bingham, G.E., S.B. Jones, D. Or, I.G. Podolski, M.A. Levinskikh, V.N. Sytchov, T. Ivanova, P. Kostov, S. Sapunova, I. Dandolov, D.B. Bubenheim, and G. Jahns. 1997. Microgravity effects on water supply and substrate properties in porous matrix root support system. 48th International Astronautical Congress, Oct. 6-10, 1997, Turin, Italy.
- Stothoff, S., D. Or, and D.P. Groeneveld. 1997. Hydrologic interactions in shallow soil overlaying bedrock discontinuities. F. ###. AGU Fall Meeting. San Franciso, CA.
- Dudley, L.M., D. Or, W.R. Mace. 1996. Use of Saline Waste Water From Electrical Power Plants for Irrigation: 1994 Report. Part 1: Soil, Irrigation Water, and Crop Yields Studies. Utah Agric. Exp. Sta. Res. Rpt. # .
- Malek, E., G. E. Bingham, D. Or, and G. McCurdy. 1997. Annual Mesoscale Study of Water Balance in a Great Basin Heterogeneous Desert Valley. J. Hydrology 191:223-244.
- Coelho, F.E., and D. Or. 1997. Applicability of Analytical Solutions for Water Flow From Point Sources to Drip Irrigation Management. Soil Sci. Soc. Am. J. 61:1331-1341.
- Jones, S.B., and D. Or. 1997. Particulated Growth Media for Optimal Liquid and Gaseous Fluxes to Plant Roots in Microgravity. Adv. Space Res. (in press).
- Jones, S.B., and D. Or. 1997. A Capillary-Driven Root Module for Plant Growth in Microgravity. Adv. Space Res. (in press).
- Jones, S.B., and D. Or. 1997. Design of Porous Media for Optimal Liquid and Gaseous Fluxes to Plant Roots. Soil Sci. Soc. Am. J. (in press).
- Wraith J.M., and D. Or. 1997. Nonlinear Parameter Estimation Using Spreadsheet Software. J. Nat. Resour. Life. Sci. Edu. 28:000-000 (in press).
- Coelho, F. E., and D. Or. 1997. A Model for Soil Water Distribution under Drip Irrigation with Root Uptake. Pesq. Agropec. Bras. Brasilia (in Portuguese - in press).
- Or, D. and J.M. Wraith. 1997. Temperature effect on near-surface soil water measurements using time domain reflectometry. p. S166. AGU Spring Meeting. Baltimore, MD.
- Or, D., F.J. Leij, and V. Snyder. 1997. Modeling post-tillage soil pore size evolution as a stochastic process. p. 164. ASA abstracts. ASA, Madison, WI.
- Snyder, V, and D. Or. 1997. Evolution of inter-aggregate pore space in structured soils. p. 168. ASA abstracts. ASA, Madison, WI.
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Progress 01/01/96 to 12/30/96
Outputs
The main accomplishments made during the first year of this project were: (i) design and testing of a new matric potential-TDR probe based on enclosing discs of several porous materials (spanning a wide range of pore sizes) within a coaxial cage (a collaborative study with Dr. J. Wraith of Montana State University); (ii) theoretical developments were made toward describing pore size evolution during wetting of aggregated soils; (iii) field measurements of water distribution from drippers under transient flow conditions to study the impact of soil variability on transient point source flow regimes.
Impacts
(N/A)
Publications
- Or, D. and U. Shani. 1996. Reply to comment on "In-situ Method for Estimating Subsurface Unsaturated Hydraulic Conductivity". Water Resour. Res. 32(6):1897
- Hipps, L., D. Or, and C. Neale. 1996. Spatial Structure and Scaling of Surface Fluxes and Governing Properties in a Great Basin Ecosystem. in: Scaling up in Hydrology ... pp. 113-125, eds. Stewart et al., Wiley & Sons, Chichester, England.
- Coelho, F.E., and D. Or. 1996. A Parametric Model for Two-Dimensional Water Uptake Intensity by Corn Roots Under Drip Irrigation. Soil Sci. Soc. Am. J. 60:1039-1049.
- Or, D. and H.R. Silva. 1996. Prediction of Surface Irrigation Advance Trajectories Using Soil Intake Properties. Irrig. Sci. 16:159-167. Or, D. 1996. Drip Irrigation in Heterogeneous Soils: Steady State Field Experiments for Stochastic Model Evaluation. Soil Sci. Soc. Am. J. 60:1339-1349.
- Or, D. 1996. Wetting-Induced Soil Structural Changes: The Theory of Liquid Phase Sintering. Water Resour. Res. 32:3041-3049.
- Or, D. and Wynn R. Walker. 1996. Effects of Spatially Variable Intake Properties on Surface Irrigation Advance. J. Irrig. and Drain. ASCE 122:122-130.
- Kavvas, M., Z. Chen, R. Govindaraju, D. Rolston, T. Koos, A. Karakas, D. Or, S. Jones, J. Biggar. 1996. Probability Distribution of Solute Travel Time for Convective Transport in Field-Scale Soils ... Res. 32:875-889.
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Progress 01/01/95 to 12/30/95
Outputs
The main accomplishments made during the third year of this project were: (i) further development of methods for in-situ measurement of subsurface unsaturated hydraulic conductivity using point sources; (ii) establishment of theoretical framework for soil water sensor placement and interpretation for drip irrigation management; (iii) field experiments and theoretical models for water uptake by plant roots under drip irrigations; and (iv) new developments in noninvasive characterization of soil constituents using electromagnetic methods.
Impacts
(N/A)
Publications
- Coelho, F.E., D. Or, and C.L. Andrade. 1995. Evaluation of Steady State Regime and Sensor Placement for Determining Water Content and Matric Potential in Drip Irrigation (in Portuguese). Pesq. Agropec. Bras. Brasilia 30(9):000-000 (in press
- Kavvas, M.L., Z.-Q. Chen, R.S. Govindaraju, D.E. Rolston, T. Koos, A. Karakas, D. Or, S. Jones, and J. Biggar. 1995. Probability Distribution of Solute Travel Time for Convective Transport in Field-Scale Soils Under Unsteady-Nonuniform Flow
- Or, D. 1995. Drip Irrigation in Heterogeneous Soils: Steady State Field Experiments. Soil Sci. Soc. Am. J. (accepted).
- Coelho, F.E., and D. Or. 1995. A Parametric Model for Two-Dimensional Water Uptake Intensity by Corn Roots Under Drip Irrigation. Soil Sci. Soc. Am. J. (tentativ. accepted).
- Or, D. 1995. Stochastic Analysis of Soil Water Monitoring for Drip Irrigation Management in Heterogeneous Soils. Soil Sci. Soc. Am. J. 59:1222-1233.
- Shani, U., and D. Or. 1995. In-situ Method for Estimating Subsurface Unsaturated Hydraulic Conductivity. Water Resour. Res. 31:1863-1870.
- Or, D. and Wynn R. Walker. 1995. Effects of Spatially Variable Intake Properties on Surface Irrigation Advance. J. Irrig. and Drain. ASCE (in-press).
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Progress 01/01/94 to 12/30/94
Outputs
The main accomplishments of this project were the development of analytical methods for characterizing effects of wetting-induced soil structural changes on infiltration and subsequently on surface irrigation efficiency. New predictive methods were developed for surface irrigation evaluation with minimal inputs. Effects of variations in soil properties on advance trajectories and irrigation system performance were developed. Data were collected in the field and in the lab to test the proposed analytical tools. We expanded last year's results by developing a new method for in-situ measurement of subsurface unsaturated hydraulic conductivity using a single measurement. This was done in cooperation with the Volcani Center, Israel. Finally, drip irrigation management in heterogeneous soils using soil water sensors was investigated. A field validation of theoretical expressions relating soil variability to matric potential (and water content) variabilities was conducted in
the Greenville farm, Logan, Utah.
Impacts
(N/A)
Publications
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Progress 01/01/93 to 12/30/93
Outputs
Two main accomplishments were made during the first year of this project. First,we developed a new method for in-situ measurement of subsurface unsaturated hydraulic conductivity in cooperation with Dr. Uri Shani (a visiting scientist from Israel). A measurement protocol based on theoretical grounds was tested and verified in field experiments conducted both in Israel (Arava experimental station)and at the North Farm, Logan, UT. A new probe for subsurface measurements was designed, constructed, and field tested. The second accomplishment was the development and preliminary tests of a new modeling approach to describe wetting-induced soil densification. The experimental part included: (1) developing measurement techniques to characterize the pre-wetting hydraulic properties (saturated conductivity and pore size distribution) of an unstable soil by using a non-polar fluid (Ethanol); and (ii) setting up a system for real-time and detailed measurements of all flow-related
attributes (including soil air pressure, matric potential, water content, infiltration rates and differential settlement) during intermittent application of irrigation water in laboratory and field experiments.
Impacts
(N/A)
Publications
- OR, D., SILVA, H. 1993. Wetting Induced Soil Structural Changes Affecting Infiltration, p.214. IN: Agronomy Abstracts, ASA, Madison, WI.
- SILVA, H., OR, D. 1993. Wetting Induced Soil Structural Changes Affecting Infiltration - Field and Laboratory Experiments, p. 217. IN: Agronomy Abstracts, ASA, Madison, WI.
- SHANI, U, OR, D. 1993. In-situ Method for Determining Subsurface Unsaturated Hydraulic Conductivity. (Submitted to Water Resour. Res.).
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