Here is the published part - Wright NA. 1998. Soil fertility variograms from “true point sampling” TM on 20.9, 0.9 and 0.1 meter grids. Comm Soil Sci Plant Anal 29(11-14):1649-1666. Do you need help with Google????

The first two paragraphs in the introduction says it all. Wonderful work studiously ignored by all – especially those taking soils samples and interpreting them. This factor and the lack of quality control in soil sample analyses by most all labs makes soil testing less than useful.