The degree of phosphorus saturation (DPS) in soil can be calculated using the equation:
DPS = P/(Al + Fe)*100,
where P, Al, and Fe are the soil concentrations of each of those elements in mmol per kg. This calculation can provide an estimation of P runoff from soil. Phosphorus concentration can be determined using Mehlich III or Ammonium Oxalate (AmOx) extraction methods for removing P from soil. This portion of research analyzed Mehlich III extracts using atomic absorption spectroscopy to determine the concentrations of aluminum and iron in the samples.