Fig. 6. Residual band Bray-1 P concentrations in the direction of application for the 20 kg P ha^-1 treatment for two plots each of the Mexico, Putnam, and Dockery soils, Fall 1997 sampling. The line represents the mean of the 10 subsamples. The upper bar represents the P value from the 2-cm band center sample. The lower bar represents an average of cell samples and the 2-cm band center sample that would represent a probed sample of 0 to 15 cm.