Replace para 2, p. 491 with:

“TheBFDCInterrogator can be used to re-examine published estimates of the critical P concentrations. For example, Holford and Cullis (1985a) concluded that the critical value (90% Ymax) was 25 ± 4 mg/kg for the Colwell soil P test on a 0-10 cm soil sample. The treatment series within the BFDC Interrogator for the NSW wheatbelt covering a similar area (approximately bounded by the Murray River in the south, and Cootamundra in the north) gave a critical value for Colwell-P of 27 (20ndash;36) mg/kg over 126 experiments with a soil pHCaCl2 <5.6. This was consistent with the value reported by Holford and Cullis (1985a).

In the northernNSWSlopes and Plains, the previously reported critical Colwell value ranged from 30 mg/kg (Holford and Doyle 1992) to 57 mg/kg (Holford and Cullis 1985b). The latter and higher estimate was derived from 49 sites reported by Colwell and Esdaile (1968) and Colwell (1970). Based on all 49 sites, which have been entered in the BFDC National Database, the critical value for Colwell-P estimated by BFDC Interrogator was 25 (18–34) mg/kg, suggesting that the value of 57 mg/kg was misleading.”

Corrigendum: References, p. 495