Thanks. I would guess based on that info that you have P available in the water and soil in a non-bound condition. Alum probably reduced the amount but the 13-13-13 and lime put the water back in good condition. You could get the LSU ag center to do a soil and water test - its not expensive and provides good data to work from.
http://www.stpal.lsu.edu/FAQ/fee.asp Soil Test and Plant Analysis Lab School of Plant, Environmental, and Soil Science Baton Rouge, Louisiana 70803
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