I am aware of some fields here that historically recieved poultry manure yearly with application rate measured in inches!!!  Soil tests show P levels at 800, 900 even up to 1600 ppm!!!  These fields had Nitrogen testing done in the past that went off the chart at 500 ppm of nitrates.  You'd think with levels that high you could grow one hell of a crop.  But, the farmer that farms them has struggled to get any tonnage off the hay and row crops do no better.  I've heard before that an excess in one nutrient means a deficiency in another.  I'm sure that is true in this situation.  Here is PA, nutrient mangament legislations requires fields that have a soil test level of P above 200ppm to be looked at in greater detail before manure application can be done.  The fields I've mentioned can not recieve any manure.