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Little River, TX | According to one theory you have an abundance of K & Mg, but could use some lime. The Labs Educated Guess is probably good.
If the CEC is really in the 24 - 25 meq/100g range you do not need any additional potash above 300 ppm K. Roughly the same for magnesium, probably 310 to maybe 320 ppm Mg.
As for the calcium I would say you want at least 3500 ppm Ca, preferably 4,000 ppm Ca. All the above is based on a 24.8 CEC. Now they are probably reporting a computed CEC value and that is computed with a magic equation that involves the test levels for K, Mg, Ca, & Na with an adjustment for pH. CEC is really a reflection of the amount of clay and organic matter in the soil, which changes very little with time. a surplus of K, Mg, &/or Ca will increase the computed CEC value. If that is your case the applied lime will increase the computed CEC. True if you do not fertilize your abundant K & Mg levels the CEC should go down as their soil test levels also go down.
Chasing a computed CEC can be like a dog chasing his tail. Fun to watch but frustrating for the poor dog.
Still the way I see thing, from way outside the box, is you have 980 lbs of K2O sitting in the bank waiting to be used. You possibly could draw down the potassium levels to 200 ppm K before you will be hurting for potash. That is 1,600 to 1,700 lbs of K2O to be used by the crop before yield will be significantly effected.
As a disclaimer, the above is using rough factors to compute desired fertility levels. I also have found computed CEC values to vary as much as 30% which I consider to be significant.
As for Boron and Sulfur, I have no trust in the reliability of soil testing to determine the availability of S or B. As far as I am concerned only a plant analysis will establish if you need Sulfur or any of the micronutrients.
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soil test
