Generally, the smaller the area, the more representative of the area the sample values will be. Figure 5 shows two examples of a suggested way to obtain representative samples from fields. Composite soil sampling plan for glacial landscapes. Composite soil sampling plan for rolling landscapes. Soil sampling is relatively quick, only 20 to 30 cores are needed to represent a field, and only one analysis is required for each field.
Results are mostly reproducible.
Results can easily be tracked from year to year. There is a low level of confidence that high soil test values represent most of the field. Sometimes it is difficult to distinguish which locations are unusual. Composite sampling is most representative when within field variability is low. Low within field variability is most common when composite soil test levels are low.