it can be determination of soil pH or know the trend, not prediction. usually, soil pH is determined in 1:2.5 soil water suspension.

Thank you, cold you recommend me a procedure or formula for the estimation of pH based on the SOM?

One can not estimate or predict pH from organic matter and texture,though the pH is influenced/buffered by organic matter and clay as explained by Dr.Mohamad.

I doubt , there any such information , where you can throw any light on soil pH based on data on organic matter and soil texture...

 good day,this file maybe help you

you cant. they don't relate to each other. soil pH depends mostly on soil calcium carbonate, ions e.g Ca and Mg, Na and K, SO4, HCO3- or CO32-.

Dr. Migoni, 1. Soil pH is not affected by soil texture. Technically, pH is a gauge of the hydrogen ion concentration in the soil and soil texture refers to the size of the soil particles.

2. Simple and multiple correlation coefficient was run between soil pH and organic matter. It depends upon type of soil , their base saturation and buffering capacity. Organic matter accumulation does not necessary result in pH decreases or increases. For example,  with an increase in organic matter, the soil recovers its natural buffering capacity, this means an increase in pH in acid soils. CEC is closely link to the organic matter content of the soil.

The answer is No.

Soil pH should be separately measured because the pH of the soil dependent on numerous factors, in particular, acidic and alkaline substances content in the soil water.

Soil pH should be measured separately. It depends on different factors - for example the quality of SOM, percentage of base saturation.

Yes,  you do to know the status of soil organic matter. Normally,  fungal dominating system generate acidic soil organic matter and bacterial dominating system neutral and little bit alkaline.  However,  measurement of pH is Separate but many physicochemical  properties of soil may correlate with pH. 

Yes, you can do it, but may be it is easier to directly mesure the pH of you're soil.

Simply I like to answer that "No".

Already Soil pH must be separately measured because the pH of the soil dependent on numerous factors, in particular, acidic and alkaline substances content in the soil water.

Soil pH is depends upon the quality of organic matter as well as per cent of base saturation. If you have the both the information, probably you may guess the pH of the soil. But definitely one should prefer to measure the pH separately as it is easy as well as accurate, and not so time consuming. 

kindly go through this link

http://landresources.montana.edu/nm/documents/NM8.pdf

Soil pH  is a master soil properties defining many processes. Its value depends pedotransfer functions of  soils. It changes to some extent seasonally. The measurement of it is so easy. What I suggest is just measure this key component to acurately evaluate your data.  

First thing , there is no empirical relation developed between soil pH and soil organic matter content . Secondly , i doubt , you can calculate CEC of soil , based on  soil texture, OM and bulk density , despite the fact that first two parameters do contribute towards soil CEC, depending upon certain prevailing conditions.. Such relations , we need to develop to fit into local/regional soil conditions or a given agropedological conditions..

You do not need pH to calculate CEC. CEC is a separate analysis. SOM could give you an idea of CEC, but not a valid number. Better if done pH and CEC separately.

What you want to do is so complex. The CEC capacity is related to some extent to pH. By using this relation you probably calculate the share of organic matter. But each soil have different degree of humicafition depending on the soil forming factors including the soil managements. Then you calculate the part of CEC related to clay minerals. But in this case the clay mineralogy will be different for different soils. Even adjacent soils can have some differences in the clay mineralogy. Therefore trying to aproximate CEC of any soil in question is useless and has very high error rate. Best way you can do just measure the parameters you need. 

It is impossible.

You can estimate the soil pH with the base saturation (%BS)