• Al-Darby,A.M., S.I. Al-Asfoor, and Y. Z El-Shafei. 2002 publish a paper explaining how to determine the water rettention carve under multi concentrations of gel-conditioer and its Effect on the other Hydrophysical Properties of of Sandy Soil . So i think you will get some of your question answer

You can refere to the full text as follows:

Al-Darby,A.M., S.I. Al-Asfoor, and Y. Z El-Shafei. 2002 Effect of Soil Gel-Conditioner on the Hydrophysical Properties of of Sandy Soil . J. Saudi Soc. for Agric.Sci. : 1: (1) 14-4...

ARTICLE · JANUARY 2002

Article Al-Darby,A.M., S.I. Al-Asfoor, and Y. Z El-Shafei. 2002 Effe...

Al-Darby,A.M., S.I. Al-Asfoor, and Y. Z El-Shafei. 2002 publish a paper explaining how to determine the water rettention carve under multi concentrations of gel-conditioer and its Effect on the other Hydrophysical Properties of of Sandy Soil . So i think you will get some of your question answer

You can refere to the full text as follows:

Al-Darby,A.M., S.I. Al-Asfoor, and Y. Z El-Shafei. 2002 Effect of Soil Gel-Conditioner on the Hydrophysical Properties of of Sandy Soil . J. Saudi Soc. for Agric.Sci. : 1: (1) 14-4...

ARTICLE · JANUARY 2002

https://www.researchgate.net/profile/Saad_Alasfoor/publication/271766604_Al-DarbyAM_SI_Al-Asfoor_and_Y_Z_El-Shafei_2002_Effect_of_Soil_Gel-Conditioner_on_the_Hydrophysical_Properties_of_of_Sandy_Soil_J_Saudi_Soc_for_AgricSci_1_1_14-40/links/54d7167c0cf25013d03667e8.pdf?inViewer=0&pdfJsDownload=0&origin=publication_detai

Article Al-Darby,A.M., S.I. Al-Asfoor, and Y. Z El-Shafei. 2002 Effe...

A respected Saif Alza Beebee. You can not reliably estimate the water retention curve for the data that you have. In general, the way an indirect estimation of these functions is not correct if you want to continue using them for engineering calculations (irrigation, drainage, crop optimization). If you have a centrifuge in a laboratory, the easiest way to evaluate experimental - use it for potential moisture depending on the humidity. I'm attaching the articles and ready to advise you on the details of the method.

Sincerely, Prof. A.V. Smagin, Dept. of Soil Science, Moscow St. University.

Yes, you can use some pedotransference model. Some models use clay or lime + clay or clay + OC. It is depending type on soil that you have 

Sincerely. Prof. Dr. Olga S. Heredia-Buenos Aires University

I think Dr. Andrey Valentinovich Smagin ·is correct and has provided lot information to study before initiating investigations.

Thank you all.

In the case of shortage of input data I suggested method of calculating the soil water retention capacity (SWRC), using an empirical relationship of Voronin. The idea is that this dependence intersects the SWRC curve at the point at which the differential soil moisture capacity reaches a maximum value. In addition, this point corresponds to the soil-hydrological constant, which is called field capacity (FC). Thus, if you have data on FC and wilting point (WC), you can estimate the values of the SWRC function using a method, which is published in my article in the journal Int. Agrophysics (2010).

Dear Saif Alzabeebee.

I agree with comments provided by Dr. Andrey Valentinovich Smagin.

Centrifuge method was one of the first used to determine moisture related with matric potential.

Now a days more used methods are pressure pots (Richards L. 1965), and WP4C to estimate soil moisture characteristic.

Also, I'm attaching a couple of paper with pedotransfer functions (models used to estimate available water from a multiple soil data like bulk density O.C. PSDA), but I believe your soil data is very limited to use them.

Greetings from Costa Rica.

You can estimate the SWCC from particle size distribution curve. For more info, see Fredlund's publications