This method is identical to Method 9I2b and Method 9I3b, except that Colwell-P and Olsen-P values, respectively, are not included in the calculation of PBI. The relevant equation is shown in Method 9I4a, Note 1, Table 9.9. The ‘finish’ includes all P in solution regardless of the chemical species present.
Report unadjusted PBI on an air-dry (40°C) basis.