Also interested in what people use the data for and what software they use for fitting data.
We're using both pressure plates method (time of equilibration depending on the matrix potential) and ku-pF (UGT's device based on the Wind evaporation's method)
In the Soil Physics Lab of Wageningen UR (Netherlands) we use different methods. Sandbox for the small tensions (h = 5 - 100 cm), the suction plate (instead of the earlier kaolin box) and the evaporation (Wind) method for the mid range (h = 100 - 700 cm) and the pressure plate foor the large tensions (h = 1000 - 15000 cm). See also http://www.wageningenur.nl/en/Expertise-Services/Facilities/Soil-Physics-Laboratory.htm
Not for "regular characterization", but we used to for a PhD study, but the goal was mainly to collect soil solution to analyse pesticides in it
Ive been exploring use of rapid approaches for determining the retention curve, including evaporative flux, classic desorption - pressure plate, and inverse simulation of infiltration data. The results are quite scary, they show the choice of method and starting moisture content determine the retention curve you get.
Ive just had the paper published in soil and tillage research 2013, 130 pp 99-108
Could you send me on the paper please
Also are people looking at hysteresis?
In Romania, the National Research-Development Institute for Soil Science uses suction plates.
Here in Brazil, at the Soil Physics Laboratory, we use the tension table for matric suctions 1 to 10 kPa; pressure plates for suctions, 33 to 100 kPa and dewpoint potentiometer, WP4 for higher suctions, say 500, 1000 and 1500. kPa. However, we do make use of pressure plates depending on the number of samples. For large samples, WP4 is much faster.
Fascinating range of techniques. What do people use the retention curves for?
In IRAN we often use pressure plate method for high pressure, hanging column for low pressure.Both methods is for drying position, and for wetting position we use vapor equivalent method for high pressure and solution equivalent method for low pressure.
Thank you.... What do you use your data for? I use it for Hydrus and travel times of conservative tracers through the unsaturated zone.
Soil moisture curve(SMC) is needed for any purposes, like soil moisture diffusivity and unsaturated hydraulic conductivity measurement. Also that is suitable for estimate and obtain soil texture(arya-paris model), calculating solutes traveling velocity in vadoze zone, infiltration rate and any more cases.
How do people saturate and de-air cores before placing in pressure plate setup? Also do people go for wet and dry curves? Also disturbed or in disturbed soil?
Tempe cells for the wet end and a WP4-T Dewpoint Potentiameter for the dry end. See: TULLER, M., and D. OR, 2004. Water retention and characteristic curve. In D. Hillel (Ed.), Encyclopedia of Soils in the Environment - Volume 4, Elsevier Ltd., Oxford, U.K., pp.278-289. TULLER, M., and D. OR, 2005. Water films and scaling of soil characteristic curves at low water contents, Water Resour. Res., Vol. 41, No. 9, W0940310.1029/2005WR004142.
In Catalonia, usually the soil physics researchers use the sand-box method to measure matric potential between saturation and pF 2.3, belong these points, the driest points of the WRC the most common device used is the pressure plate. Even though, some researcher, even I, we are using a Hyprop system, with an excellent results. The WP4C hydrometer I sed as well, but in this case the accuracy is considered up to -80 kPa. If the sample are wet than this point, the WP4C is not accurate and reliable.
Regarding the software, I use the own Hyprop software, sometime a direct VG equation, and Rosetta or site-specific PTF's developed by myself, though.
Here is the ku-pF apparatus from UGT company (http://ugt-online.de/en/produkte/bodenkunde/messgeraete-fuer-die-hydraulische-und-pneumatische-leitfaehigkeit/ku-pf-apparatur.html). Then we used either Rosetta or a model developped by Peters et al 2011 (Consistent parameter constraints for soil hydraulic functions) to calculate hydraulic parameters.
For software, I have used:
ROSETTA (http://www.ars.usda.gov/services/docs.htm?docid=8953)
and
RETC (http://www.pc-progress.com/en/Default.aspx?retc)
I know also of SolPar but I have not really looked further into it (http://www.sipeaa.it/ASP/ASP2/SOILPAR.asp)
I am not sure if Dr. Fenton still has interest in this information, but in Brazil the soil scientists commonly use sand-box from saturation to around -10 kPa matric potential and Richard’s chamber and WP4 from -10 kPa to the permanent wilting point. For the mathematical adjustment of the SWRC, the Excel solver has been used in my laboratory. Rosetta is also sometimes utilized to fit the curves.
In our lab (Maringá State University-Brazil) we use tension tables from saturation to 100 hPa. For tensions varying from 100 hPa to 800 hPa we use minitensiometers (we don't use richards chambers anymore) and for measures higher than 800 hPa we use the WP4 (Decagon).
In our lab (Soil Laboratory - School of Agricultural Engineering - UNICAMP, Brazil) we use tension tables from saturation to -6 kPa matric potential and Richard’s chamber and WP4 from -10 kPa to -1500 kPa.
Buchner funnel apparatus coupled with Richard's chambers. Alternatively, I use also the evaporation method (CREA-AA, Bari, Italy).
Best
Mirko
We measure the retention function at the Hydrology Lab (University of Napoli). Soil water content values are measured at prescribed soil water matric head values from near-saturation up to -200 cm using suction tables (Romano et al., 2002). Other additional soil water retention points are determined with the pressure chamber method at prescribed low matric head values (let's say from -3000 cm till wilting point for example)
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