Soluble forms of humate are likely what you need.
It allows you to reduce fertility requirements (N-P-K).
It allows you to use lower rates of herbicides when you do use them. Weed control rates can be lowered by about 15%. Round-up by up to 50%.
What else do you want to know? Just ask.
Soluble humates have a CEC of over 500. They also have >50% organic carbon.
However, use rates are generally pretty low for these products and they are not necessarily a direct means to increase CEC and OM.
They can do this however. Citrus groves in FL have increased OM by 1% in one year using 25 lbs per treated acre of soluble humate. You would probably need to have a valuable crop to afford this much soluble humate in one year.
Leonardite can be used to facilitate soil changes in southern sandy areas too. It is cheaper, less predictable in terms of biostimulant properties, and may sit on top of the soil for a while if not being tilled in, but it does very closely resemble the structure of native soil organic matter and that allows it to facilitate increases in CEC and OM.
There are no real rate restrictions on Leonardite - it is mostly an economic issue. There are a lot of companies in Texas selling humates. I will not speculate on each one, but from my experience, many of them are not high quality. You will need to do some homework on this to be comfortable with your purchase.