Manures are good sources of phosphorus

Animal and poultry manures are often evaluated on the basis of their nitrogen content. Field experiments in the Antelope Valley on producing alfalfa fields have shown that poultry, steer, and dairy manure are also good sources of phosphorus. In this study, yield comparisons were made between treble superphosphate and manures when applied in amounts to provide the same rates of phosphorus as conventionally used on alfalfa.