What are the P numbers on the soil test. Remember that your applied P will tie up if not used by the plant, it is hard to build available P levels over what is naturally available based on soil biology unless using a biological program which you are doing some with cover crops.

The only place I see high P levels are live stock farms that can cover every acre every year but then you have run off problems.

I would not spend the dollars if your P1 is over 25ppm.