Dear Tarik,

I hope you are asking about "soil moisture" (not humidity). If so, you can try ROSETTA software from the following link. ROSETTA is a computer program for estimating soil hydraulic parameters with hierarchical pedotransfer functions.

http://cals.arizona.edu/research/rosetta/rosetta.html

Good luck

Zafar

Hi Tarik!:

Soil moisture at field capacity is easy to determine experimentally from soil water retention curve at -33 kPa. In the case of wilting point you can use one of several pedotransfer functions as suggested Dr. Hashmi.

Cheers Dr. Millan

Hi Tarik

Here is a website that has a program that can give you estimates.

http://www.nrcs.usda.gov/wps/portal/nrcs/detailfull/national//?&cid=stelprdb1045331

John

Hi Tarik,

You can use SPAW which gives you des precious information on the hydraulics and physics of your soil which takes into account the rock fragment of the soil too.

http://hydrolab.arsusda.gov/SPAW/SPAWDownload.html

Enjoy!

Behzad

You could use pedotranfer functions such those refereed in previous answers. Please note that the soil water potential at field capacity depends of the textural class. Generally for fine-textured soil (clay) the water potential is higher (-0.01 vs. -0.033 MPa). Direct field measurements are easy 2 days after a large rain event. The wilting point is species-specific. The classic agronomic value is originally for maize (-1.5 MPa). You could use pedotranfer functions such those refereed in previous answers. Please note that the soil water potential at field capacity depends of the textural class. Generally for fine-textured soil (clay) the water potential is higher (-0.01 vs. -0.033 MPa). Direct field measurements are easy 2 days after a large rain event. The wilting point is species-specific. The classic agronomic value is originally for maize (-1.5 MPa). 

Regards

Serge

This is a simple use of thermodynamics and is in every soil physics text book.  Go to the library and read one of them.  There is a good description in "An Introduction to Environmental Biophysics" by G.S. Campbell (page 29).  At wilting point it is 97% , so even dry soil is humid. 

As answered previously by colleagues, you can use pedotransfer function to estimate fc and pwp moisture content. you can follow the software, link for which is given below

http://www.cazri.res.in/soil-moisture-calc.php

Kind regards

Priyabrata Santra

Sr. Scientist, CAZRI, India

You are talking about pedotransfer functions. As for the available free software there are the following:

The RETC software where you are going to choose as “type of problem”,“No fitting (forward problem)” and then at the same submenu “entire curve” or “data points”. By this software you can predict Curve or points by a number of available models eg Van Genuchten’s, Brooks and Corey etc, and by a nymber of available data. You can also calculate the K(Θ) curve with Burdine’s or Mualem’s models.

The Rosetta Software

The “Soil Water Characteristics” incorporating Saxton model

The SoilPar software.