9I4a P buffer index – PBI_unadj – Murphy and Riley

This method is identical to Method 9I2a and Method 9I3a, except that Colwell-P and Olsen-P values, respectively, are not included in the calculation of PBI. The relevant equation is shown below and explained in more detail in Table 9.9 of Note 1.

Calculation of unadjusted PBI

where:

Table 9.9. Data and calculatŠns required to calculate PBI_unadj.

Ps = freshly sorbed Pl (mg P/kg); and

c = final solution P concentration (mg P/L)

Report unadjusted PBI (PBI_unadj) on an air-dry (40°C) basis.

Note

1.  Calculations can be conveniently performed on a computer spreadsheet. Guidance is provided in Table 9.9.