First I do hope they used the Olsen ie. Sodium Bicarbonate test for phosphate. I strongly suspect they used Mehlich II. We will have e to go with what we have for now.
So here goes; I would say 60 lbs is a good guess for phosphate. With your calcium levels I would suspect you have at least a 10% free lime situation. In that case consider applying double that 60 units of P2O5 at least on a few rows. Realize not all Blackland Clay soils are the same. They look the same but have different clay types. Assuming you truly have a 30 meq/100g CEC soil type, that likes to crack when dry I would look for a potassium test level in the 360 ppm range. Some of my soils are in the 50 meq/100g CEC range. These are Trinity Clay soils, but the Wilson Clay soils are just as bad! Where you apply 120 lbs/A P2O5 also spread 500 lbs of Murate of Potash (0-0-60). Fondly referred to as MOP.
I hope you did not pay extra for the micro nutrients and sulfur. This summer, at the stage A&L suggest, clip tissue samples from each field. From the as recommended parts and the added P & K area(s). Tissue analysis is the only really reliable discovery of available micro nutrients as well as sulfur and possibly for phosphate and Magnesium. That should be a test question.
In my opinion A&L at Memphis can provide as good a raw data as any other lab with the exception of TAMU's. I have zero confidence in TAMU soils people. For a recommendation to be of any use the lab must have crop response data from the soil type being tested. What I am saying do your own recommendations.
See if A&L will test for a measured CEC value. May cost $40 a sample, but till the clay turns to sandy the CEC will stay the same. See if they will test for percent of free lime. If A&L is using the Olsen chemistry you want 18 ppm P soil test. For rented land 12 ppm P and banding phosphate will work. Then if and another if Phsphate analysis is discovered using Olsen chemistry, you can figure 17 lbs/A P2O5 for each desired increase in ppm P plus an additional 10 lbs for each percentage of free lime. This is because the calcium in will tie up the phosphate into a Calcium Phosphate some of which are definatly not available. Do not dispare though as eventually this phosphate will be recovered. I pelieve I am recovering some of the phosphate my father put out in the 1950's. The Potash is essential for efficient water utilization. I say we are in the 5 th month of the drought of 2008.
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