Talk:Water retention curve

Hysteresis
.There is no unique relationship between Ψ and θ because moisture relations exhibit hysteresis. Diurnal hysteresis presents a huge challenge in measuring soil moisture content with intruments that measure potenntial.

Hysteresis arises from differences in (soil) wetting behaviour causing dry soil to re-wet. Hysteretic behaviour means that, for example, at a tension of 5kPa (0.05 bar) the water content of a field fine sand sample could be anything between 0.08 vwc to 0.25 vwc.(This is a worst scenario but has been recorded).

See, , 

Paleorthid 21:25, 5 April 2006 (UTC)

Graph incorrect
The graph shown is incorrect. Matric potential should be negative kPa, not positive. Atrian 16:36, 27 December 2006 (UTC)

The graph is indeed correct. Often times the absolute value of potential is shown to eliminate the need for a negative y-axis.Mjt9400 (talk) 16:20, 19 November 2009 (UTC)

kPa is much more commonly used than hPa and would be preferable for the graph Haresfur (talk) 22:30, 14 April 2020 (UTC)

Curve Models
I changed the heading to reflect that this section talks about modelling the curves not just the parameters. Hopefully, others will be added as they are alluded to in the text.Haresfur (talk) 22:57, 14 April 2020 (UTC)

The description of the van Genutchen model is incomplete because the meaning of the different parameters (and how they are determined) is absent. The van Genutchen model might warrant its own page but I'm not knowledgable enough to add the content here or on its own page.Haresfur (talk) 22:57, 14 April 2020 (UTC)

Graph captiontext is incorrect
The graph contains the german soil type discriptions, Ss is sandy sand or (pure sand), Uu silty silt (or normal silt), Ll is loamy loam and Tt clay clay. there is no graph for peat See Ad-Hoc-Ag Boden, Bodenkundliche Kartieranleitung, Edition 5, ISBN 3-510-95920-5 Feb. 19. 2010 Christian K

Reference
Plan to see this developed into an inline cite in support of the importance of the Buckingham 1907 related article content:

Buckingham, 1907: An Appreciation

T. N. Narasimhan Vadose Zone Journal 4:434-441 (2005). doi:10.2136/vzj2004.0126 Convenience link: http://www.olemiss.edu/sciencenet/saltnet/buckingham_1907_vaj_may_05.pdf.

"Nearly a century ago, Edgar Buckingham published a seminal work on the movement of soil moisture that is part of the foundation of modern soil physics. It also constitutes a pioneering contribution in the study of multiphase flow in porous media." -- Paleorthid (talk) 18:12, 18 January 2016 (UTC)

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