Hay Wilson in TX - 7/23/2009 09:21

In the dark past I thought the high pH & excessive native lime was the primary problem.
Then I started learning about the effect of a high CEC. That was and is an interesting path.
The latest is I find that not all clay soils are the same. One, the one found on this farm, has a high shrink swell ratio and tends to crack when dry. This clay goes by the name Vertisol or Vertic depending on how it is used in a sentence.
I now believe it is this Vertic character that is responsible for this soil requiring an excessively high soil test for potassium to insure the crop has adequate tissue levels of potassium.
Interestingly enough the CEC correction factors for cations I found in Pennsylvania's' Web Site may be barking up the wrong tree but they still are valid!
It was DR Ken Cassman, formally in California and now at Nebraska/Lincoln who had the key.
These Vertic clay soils are in the form of platelets of silica and chemical elements are trapped between these plates. The standard soil test procedure of drying a sample separates the plates, and the extracting chemicals find these elements and report them as available. When in the soil they were not available to the crop, at the time of sampling.

I both hope and assume I will continue to learn. I presume the final truth as I now understand it will be greatly modified over time.

One thing that is true about these Texas Blackland Clay Soils is they are not all the same. Some are calcareous and others are not. Some clays if left undisturbed will have hog or buffalo wallows that will be formed by different processes again depending on the local soil.

One interesting, to me, truth for this soil is nitrogen does not leach out of the root zone, but is trapped in the clay. Some tied in the cation complex of the CEC world, and some tied up in clay packages.

What is discouraging is much of this soil knowledge is hidden in isolated sources and is not incorporated into the general knowledge base as being part of the universal truth.
The truth as it applies to the sandy soils of New Jersey are assumed to be the universal truth rather than a component of the much larger picture. In California a different component of the big picture becomes buried in California and possibly is lost even to California Agriculture because it does not agree with what was printed at Cornell sixty years ago.
The soils department at TAMU give lip service to high pH but do not appear to understand high pH as a result of all that free lime found in calcareous soils.
Enough