Simple, precise, equation.  Good luck.  it is difficult to map soils precisely by soil type. There are variances within soil types. Perhaps you have uniform soil conditions or want to do this for a confined area.  To achieve what you want, I would imagine you need to measure quite a few things, soils, plants (perhaps indicators), soil, water tension.   Not all plants have the same rooting depth or wilt at same point.  Confine it to your specific conditions for best results, and if it works out well, expand to other areas.

Simple, precise, equation.  Good luck.  it is difficult to map soils precisely by soil type. There are variances within soil types. Perhaps you have uniform soil conditions or want to do this for a confined area.  To achieve what you want, I would imagine you need to measure quite a few things, soils, plants (perhaps indicators), soil, water tension.   Not all plants have the same rooting depth or wilt at same point.  Confine it to your specific conditions for best results, and if it works out well, expand to other areas.

Simple, precise, equation.  Good luck.  it is difficult to map soils precisely by soil type. There are variances within soil types. Perhaps you have uniform soil conditions or want to do this for a confined area.  To achieve what you want, I would imagine you need to measure quite a few things, soils, plants (perhaps indicators), soil, water tension.   Not all plants have the same rooting depth or wilt at same point.  Confine it to your specific conditions for best results, and if it works out well, expand to other areas.

Naveeen , your question is very pertinent , but most of the attempts have been made out of saturation percentage as a function of soil texture , but not organic carbon .  Find below some of the PDfs dealing with these issues working on  simple linear  regression models. Hope , you find them useful.

Anoop, thanks for nice papers, it is a newer concept of determining FC and WP from saturated moisture content, but one limitation that for sandy and loamy sand soils the release of moisture is very fast from saturation to wilting point, so it may deviate from the relationship, or exponential trend may fit,

I have done lot of work on moisture retention from soil texture and oc, but the error association is somewhat not satisfactory.

In crop models, we need moisture constants, which are not readily available and need to be derived

regards

Very well said Naveen , I agree with your precise remarks. Moisture retention characteristics is like this Naveen when we consider coarser textured soils . We need to attempt at some non-linear models , unlike clay textured soils.

Natural soil is a highly organized system. Texture is a primary physical quality of soil that determines space for air and water in soils.

Texture has a role in water content of soil at the basic level of its organization; immediately after a rain, if clayey soils have more of hygroscopic water, sandy soils will have more of plant available field water!

But  water holding capacity of natural soils depends more on its structure!

Carbon content is meaningful when soil is quite natural - a living system!

If we want to know 'field water capacity' from texture, that is just like trying to know number of rooms in a building on the basis of the size of the bricks by which it is made of. Yes, there is reason to inquire so, but the answer depends on answers to many other counter questions!

Once the soil become highly structured, texture plays least role in water holding capacity

Interesting Joseph. Can you share any of your publications on these issues , it will be nice reading them . thanks

Thank you very much Dr Srivastava; I did my Ph D in Soil Ecology in the former USSR - in the traditional Dokuchaevian School of Soil Science; publications related to those are uploaded in my Research Gate profile. But currently I am not involved in research related to soil structure.