Historically, university scientists have provided research based guidance to producers and consultants on the number of soil cores per sample to collect from a given land area for soil testing. This guidance assumed that the entire sample would be dried, ground, and mixed before subsampling for chemical analysis. With pressure to improve efficiency of operations, some laboratories have resorted to grinding a portion of the sample volume and discarding the remainder of the sample. The primary objective of this project was to evaluate the variability associated with the grinding and thorough mixing of an entire sample as compared to the grinding and mixing of a portion of the field sample and to determine if tillage or soil type had an influence on this variability. To conduct this experiment, we collected soil samples to a 18 cm depth from five soil series in Illinois, with each series having 2 different tillage systems (no-till versus conventional) and 2 widely differing phosphorus levels (P<40 and P>100). Five replications were taken at each site, with samples including: 1 sample of 3 cores, 2 samples of 5 cores and 1 sample of 5 cores that was split into a 7.5 cm layer and a 7.5-18 cm layer. Each sample, except one, was ground and thoroughly mixed. Only 3/5th's of one 5 core sample was ground and thoroughly mixed. Each sample was analyzed for P, K and pH. The results showed no significant difference in P, K and pH associated with the number of cores taken per sample and in how they were processed. However, there was a significant difference of P and K between the 0-7.5 cm and 7.5- 18 cm layer in no-till and conventional fields. The number of cores taken had no impact on the variability in soil test results.