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Little River, TX | Paul's data is high, of course he knew that. His information is to instruct.
Regardless the phosphate is high for an Olsen test. Most like to fertilize up to 20 ppm P.
If that CEC value is even close, 286 ppm K is sufficient. You should see maybe a 20% possibility of yield increase with potash added above 290 ppm K.
I assume that CEC is a computed value and it may be useful but then again it may be way off. The thing is CEC is a function of quantity and type of clay with some effect from organic matter.
A computed CEC is usually derived by the equation K/A + Mg/B + Ca/C + Na/D and with a pH adjustment. (There must be 10 or more magic equations to compute CEC.) With the VH K levels that would increase the CEC value. If the Mg, & Ca are also elivated to VH levels than the computed CEC would not agree with a real chemical analysis, measured CEC value.
I would suspect this ground has seen a fair amount of animal waste of one kind or another.
For you on the higher pH fields the Bray will report phosphate lower than available to the crop.
Your potash levels are in the sufficiency range. You could bet that potash cost will go down an skip some for a few years, or you could bet the potash prices will go up and add some now to pad the cost for later.
Soil testing is so arbitrary depending on the lab doing the test and their distance from you front gate that I have a low confidence level for soil test. For plant analysis you can have any lab in the country run the samples for you and use their recommendations with reasonable confidence. Soil testing is fair, if one you know your soil, and know what your soil should be using your current Lab. Change Labs and you start all over again.
To my thinking fertilizing according to some soil test is not much better than making a wild guess. But then again I have had some bad fertility information dumped on me.
Edited by Hay Wilson in TX 9/22/2008 18:25
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Very High P&K levels need any fertilizer?
