Phosphorous and potassium varies from state to state or region to region. One bushel of corn generally has about 0.4 lbs of P2O5 and 0.350 lbs of K2O. However fertilizer recommendations will not exactly follow these nutrient removal benchmarks. Proper soil testing along with fertilizer recommendations are necessary for proper fertilizer application.
For these recommendations consult:
Kansas State: http://www.oznet.ksu.edu/library/crpsl2/mf2586.pdf
Michigan State: http://www.css.msu.edu/SPNL-SoilTestReport.cfm
Mississippi State: http://msucares.com/crops/soils/index.html
North Carolina State: http://www.ces.ncsu.edu/plymouth/cropsci/cornguide/Chapter3.html
Penn State: http://www.aasl.psu.edu/SOILRecHdbks.HTM
Virginia Tech: http://www.soiltest.vt.edu/
For more information on this or other topics related to corn production, contact your state extension corn specialist or your local extension educator/agent.
The following is the link to the corn extension specialists: state extension corn specialist